Tekmar Eight Stage Boiler Control 258 User manual

C
26 27
Zone
10K
0.4
2.0
3.6
Heating Curve
22°F
242
DemR
12 5678
Pmp
Eight Stage Boiler Control 258
Dem
HeatSystem
Pmp
910 28
Sen
Com
Sw
UnO
29 30
Sen
Sup Out
Power
Minimum
120°F
Off 170
Boiler
Differential
80
Power Supply: 24V 60Hz 5VA
Relay capacities: 24V 10A
Test
No power here
Maximum 24 volts
34
Stage Sen
H1077
Date
S/N 221092 1234567
11
11 12
Stage
22
13 14
Stage
33
15 16
Stage
44
Power
Heat
Demand
Minimum
WWSD
Pump
Stage 1 Stage 2
Comb. Air
Stage 3
Stage 6
Stage 5
Stage 8
Stage 7
Stage 4
Menu Item Override
Setpoint
S
PRGM
TEMP
FC
Actual
Supply
Target
Supply
TIME
USE
AMPM
UNOCC
OVR
MTWTFS
OUTSIDE
ROOM
1
2
17 18 19 20 21 22 23
Air
Comb.
24 25
Stage
55
Stage
66
Stage
77
N/C
88
N/OCom
M
tekmar
Zone
Control
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Rotate
8
- Data Brochure
Eight Stage Boiler Control 258
D 258
07/93
Terminal Plugs:
Power and out-
put connections
LEDs and
LCD screen;
display of times
& temperatures
Boiler
Differential
setting
Heating Curve
setting
Minimum
Supply setting
Terminal Plug:
Sensor and
timer inputs
Test button &
LED to test
main control
functions
System Pump
is on
Programming
buttons
Eight Stage Boiler Control 258
Power
Heat
Demand
Minimum
WWSD
Pump
Stage 1 Stage 2
Comb. air
Stage 3
Stage 6
Stage 5
Stage 8
Stage 7
Stage 4
Menu Item Override
Setpoint
Actual
Supply
Target
Supply
S
PRGM
TEMP
FC
TIME
USE
AMPM
UNOCC
OVR
MTWTFS
OUTSIDE
ROOM
1
2
Operating Mode
selector switches
Heating
is required 24Vac power supply is on Combustion air
damper is open
System is in
Warm Weather
Shut Down
Control is
maintaining
Minimum Supply
Input: Outdoor
Sensor 070
Included
Input: Supply
Sensor 071. Included
Input:
Unoccupied
signal.
Optional
Input:
tekmar 10K
Zone Control
Optional
Output: Turn on stages #1 to #8
Output: Open
Combustion Air
Damper
Input: Heat Demand
signal.
Optional
Output: Turn
on System
Pump
24Vac power supply
Stages 1 to 8
are on
Outdoor Reset Strategy . . . . . . pg. 2 Error Messages . . . . . . . . . pg. 14
Sequence of Operation . . . . . . pg. 4 Programming . . . . . . . . . . . pg. 15
Installation . . . . . . . . . . . . . . . . . pg. 7 Pre-Programed Schedules pg. 18
Settings . . . . . . . . . . . . . . . . . . . pg. 10 Technical Data . . . . . . . . . . pg. 19
Testing . . . . . . . . . . . . . . . . . . . . pg. 13 Limited Warranty . . . . . . . . pg. 20
The tekmar Eight Stage Boiler Control 258 is a microprocessor-based control which
regulates the supply water temperature from up to 8 boilers based on the outdoor air
temperature, and optionally, the indoor air temperature through a tekmar 10K Zone
Control. TheSystempumpis turned on whenthereisa Heat Demand andtheoutdoor
temperature is cool enough to require heat in the system. When a combustion air
damper is used, it must be opened before the first boiler is fired. The control has a
built-insetbacktimerandLCDscreentodisplaytemperaturesandboilerrunningtimes.

Shifting the Heating Curve
(a) Manually, at the control:
The Occupied and Unoccupied room temperature settings of this control
can shift the WWSD point up or down from 35 to 105°F (2 to 41°C).
(b) Automatically, using room temperature feedback:
Inaddition toa SupplySensorand anOutdoor Sensor,this control canuse
a tekmar 10K Zone Control to provide room temperature feedback for
added comfort and system flexibility.
The control still calculates a desired supply temperature based on the
Heating Curve setting and the outdoor temperature.
If the air temperature in any one zone is too cold, the control will shift the
HeatingCurve (andWWSD point)
up, whichraises thesupply temperature
until the zone warms up again. The zone control will operate zone valves
or pumps in the warm zones to prevent overheating in those zones.
If the air temperature in all zones is too warm, the control will shift the
HeatingCurve(andWWSD point)
down, whichlowersthe supplytempera-
ture until the zones cool down.
Correct setting and shifting of the Heating Curve... the key to More Comfort and Energy Savings.
Heating Curve
Asoutdoortemperaturesbecomecolder,heatlossesfromabuildingincreaseandrequiretheadditionofmoreheatinordertoprevent
the indoor air temperature from becoming colder as a result. This tekmar reset control measures the outdoor temperature, and as
the outdoor temperature becomes colder the control will balance the heat loss by making the heating supply water hotter.
The Heating Curve is used to calculate exactly how hot to make the supply water at different outdoor temperatures, as it determines
the number of degrees the supply water temperature is raised for each degree the outdoor temperature falls.
Setting the Heating Curve
Two examples of how the Heating Curve works are illustrated in the following diagram.
—With a 2.4 Curve, the supply water temperature is raised 2.4 degrees for every degree of outdoor temperature drop.
If: WWSD point = 70°F and Outdoor temperature = 30°F, then supply temperature = 166°F
—With a 0.6 Curve, the supply water temperature is raised 0.6 degrees for every degree of outdoor temperature drop.
If: WWSD point = 70°F and Outdoor temperature = 30°F, then supply temperature = 94°F
2
• If the Heating Curve selected is too low; the heating system will not
supply hot enough water to keep the room temperature warm,
particularly during the colder weather.
• Ifthe HeatingCurveselectedistoohigh; thesupplywaterwillbetoo
hot for the conditions and the building will overheat, particularly
during the colder weather.
Warm Weather Shut Down (WWSD)
At warm outdoor temperatures, the indoor space of a building gains heat
fromthe outdoors;additional heatisnot required,and ifthe heating system
is running (even on standby), enough excess heat can be produced to
overheat the building, causing discomfort and wasting valuable energy.
This control shuts off the boilers and system pump when the outdoor
temperature is above the WWSD point.
As outdoor temperatures get colder, there comes a point where the heat
gainturns intoheat loss;the heatloss causestheindoortemperaturetofall
below the comfort level, and the heating system must be turned on.
Refer to the tekmar Essays E 001 and E 002 for more detailed information regarding control strategy and integration of control functions.
Outdoor Reset Strategy
A very cool zone temperature can shift the curve far enough up to bring the control out of WWSD at warm outdoor temperatures.
Very warm zone temperatures can shift the curve far enough down to put the control into WWSD at cool outdoor temperatures.
To provide heat to the building, this control opens the combustion air damper (if one is used), turns on the system pump and fires
theboilerstodeliverheatatthelowoutputrequiredbytheHeatingCurveneartheWWSDpoint.Iftheoutdoortemperaturerisesabove
the WWSD point, the control shuts the heating system off again, and since the system was operating at a low heat output level,
overheating and temperature swings in mild weather are avoided.
When the outdoor temperature is near the WWSD point and the building is too cold; the WWSD point should be raised.
When the outdoor temperature is near the WWSD point and the building is too warm; the WWSD point should be lowered.
Outdoor air temperature
Supply water temperature
50
(10) 30 (-1) 10 (-12) -10°F (-23)°C
110
(43)
70
(21)
70
(21)
90
(32)
210
(99)
170
(77)
150
(65)
130
(54)
190
(88)
3.6 3.0 2.4 2.0 1.6
0.8
0.4
1.0
0.6
90
(32)
50°F
(10)°C
Heating
Curve
WWSD
Point
1.2
Outdoor air temperature
Supply water temperature
50
(10) 30 (-1) 10 (-12) -10°F (-23)°C
110
(43)
70
(21)
70
(21)
90
(32)
210
(99)
170
(77)
150
(65)
130
(54)
190
(88)
3.6 3.0 2.4 2.0 1.6
0.8
0.4
1.0
90
(32)
50°F
(10)°C
Heating
Curve
WWSD
Point
will
shift
up and
down
with
shift of
Heating
Curve
1.2
UP DOWN
UP DOWN
Parallel Shift of Heating Curve
0.6

3
Notes on the operation of a PID control and the effect of the PID processing function on target temperature
calculations and control response to temperature change.
In order to reduce excessive temperature droop or overshoot
andmore smoothlystage theboilerson andoff, thiscontrol uses an
advancedProportional+ Integral + Derivativeprocessingalgorithm
to calculate target temperatures. When a desired temperature
–suchasasetpoint–isprogrammedintothecontrol,thecontrolwill
initially use that setting as the exact target temperature. The PID
function however, can affect the calculation of the target tempera-
ture in two significant ways. As an example; when there is a rapid
increase in the actual temperature (Derivative), the control will
calculate a lower target temperature than the setpoint in order to
slowdownorreversethestagingonoftheboilersor;whentheactual
temperature remains above the setpoint for a long period of time
without changing (Integral), the control will calculate a lower target
temperature in order to more quickly stage the boilers off. Any
change in the calculated target temperature will show up as a
temporary deviation in the LCD target temperature display. The
deviation in target temperature will be reduced as the actual tem-
peratureapproachesthedesiredtemperature.Thisdisplayfunction
can be a useful tool in troubleshooting system problems, and is
discussed in more detail in other sections of this brochure.
Theeffectof the derivative functioncaneasily be viewed when
the "target temperature" fixed display is selected. Certain rapid
control adjustments will have a temporary effect on the target
temperature. By quickly turning up the Heating Curve dial for
instance, the operator will introduce enough derivative error to the
control to drive the target temperature artificially high for a few
seconds. This type of control response is no cause for alarm since
the displayed target temperature will automatically return to normal
when the dials are left alone for 20 seconds, as the control resets
itself. This type of reaction to a sudden change illustrates an
important point that should be considered when designing with PID
controls.
Flow rate and system load changes should be made as
slowly as possible in order to prevent overreaction by the control.
The effect of the Integral function can also be easily viewed by
not allowing a rise in supply temperature when the control asks for
more heat. The displayed target temperature will show a slow but
steady increase, illustrating another important point. Whenever the
control asks for a change in temperature – ie. stages a boiler on or
off – the control sensor must be able to detect a change as soon as
possibleoritwilloperatetoomanyboilers.(Donotinstallsensorson
return lines). If a multiple boiler system has adequate, continuous
flow and slowly changing load conditions, the result will be very
smoothstaging, minimal temperature droopor overshoot and oper-
ating characteristics that will provide stable temperature control.
The 258 Display
PRGM
FC
S
TEMP
TIME
USE
ROOM OUTSIDE
AMPM
UNOCC
OVR
SMWTFT
1
2
On when any
temperature
is displayed
On when any
time is displayed
On when displaying setback
program selection or when
programming setback
schedule
Alpha/numeric
time/temperature
display elements
On when the room
temperature selection
is displayed On when the outdoor
temperature is displayed
On when the control is
operating on the #1 setback
program event
On when the control is
operating on the #2 setback
program event
Slowly flashes on & off (temporary),
or is on constantly (permanent),
when override function is operating
Day of week
marker on when
time is displayed
On when any
boiler running
time is displayed
Either °F or °C marker
on when temperature
is displayed
Either AM or PM marker on
when time is displayed
Either OCC or UNOCC
marker on when time or
temperature is displayed
The 258 "Fixed display" options. All other displays will time-out to "ACTUAL SUPPLY – #1"
after 20 seconds with no keypad action.
See "Programming" Section, Pg. 15, for description
Setpoint
Actual
Supply
Target
Supply
F
S
TEMP
OCC
SMWTFT
ACTUAL SUPPLY – #1
F
S
TEMP
OCC
SMWTFT
Setpoint
Actual
Supply
Target
Supply
TARGET SUPPLY – #2
S
TIME
PM
UNOCC
SMWTFT
1
TIME/DAY – #4
F
S
TEMP OUTSIDE
OCC
SMWTFT
OUTDOOR TEMP. – #3
Default fixed display. When
first powered-up, or when
other displays are allowed to
"time-out", the control will
constantly display the supply
sensor temperature.
This fixed display shows the
supply temperature that has
been calculated by the
control to meet the require-
ments of the Heating Curve
or setpoint.
This fixed display shows the time
of day, day of week and some of
the current program operation
information.
This fixed display shows the
outdoor temperature sensor
reading.

4
Test
Power
Heat
Demand
Minimum
WWSD
Pump
Stage 1 Stage 2
Comb. Air
Stage 3
Stage 6
Stage 5
Stage 8
Stage 7
Stage 4
Menu Item Override
Setpoint
Actual
Supply
Target
Supply
S
PRGM
TEMP
FC
TIME
USE
AMPM
UNOCC
OVR
MTWTFS
OUTSIDE
ROOM
1
2
Sequence of Operation
258 indicator lights
Heating Operation
The 258 control must have the Reset/Stpnt selector switch set for "Reset", and must
receive a Heat Demand signal before it can operate in the heating mode .
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Thereareeighteenlightsonthefrontofthecontrolthatwillaidintestingandtroubleshooting. Duringnormaloperation,these
lights indicate the following functions:
"Power" light on • the24Vacpowersupplyhasbeenconnected toterminals PowerC–R (1and2),andisenergized.
"Setpoint" light on • the Display is showing the programmed setpoint temperature.
"Actual Supply" light on • the Display is showing the current supply sensor temperature.
"Target Supply" light on • the Display is showing the control's calculated target supply temperature.
"Heat Demand" light on • the control is receiving a 24Vac external Heat/Setpoint Demand signal at terminals Heat
Dem (5 and 6)
or theHeat/SetpointDemandselectorswitch isin the"Permanent"position or a10K ZoneControl
is connected and is creating a Heat Demand.
"WWSD" light on • the control is in the "Reset" mode, the outdoor temperature is above the WWSD point and the
control has shut the heating system off.
"Minimum" light on • the control has calculated that it must operate the boiler(s) to maintain the Minimum Supply
temperature until the outdoor temperature is cold enough to allow Heating Curve operation.
"System pump" light on • the system pump relay is on, closing the contacts between terminals System Pmp (3 & 4).
"Comb. air" light on • the combustion air relay is on, closing the contacts between terminals Comb. air (7 & 8).
"Stage 1 to 8" lights on • aboiler relayison, closingthe contactsbetweenterminals Stage1 (9 &10), Stage2 (11 &12),etc.
"Test" light on/flashing • the control is going through the programmed test routine/is halted in test routine.
When the Eight Stage Boiler Control 258 is powered-up, the "Power" light will come on and the full display along with all of the red
temperatureindicatorlightsareswitchedonforapproximately5seconds. TheDisplaywillthendefaulttoshowthe"ACTUALSUPPLY"
fixed display mode and the control will enter the operating mode. A "fixed display" is one which will show its information continuously,
and the four fixed displays available to the user are illustrated on the previous page. More information on access to displays and on
programming is available in the "Programming" section, starting on page 15.
Once in operating mode, the control uses the Outdoor Sensor 070 to continually monitor the outdoor temperature, and the Universal
Sensor 071 to continually monitor the system supply water temperature.
Indoor temperature can be monitored through the use of a tekmar 10K Zone Control
(Optional; must be ordered separately)
Whilemonitoringthesetemperatures,thecontrolrecognizesavarietyofconditionsandinputs,andwilloperatethesystemasdescribed
below. During operation, the lights on the front of the control – illustrated above – will indicate how the system is operating.
ByreadingthissequenceofoperationsectionandcomparingittowhattheindicatorlightsandtheL.C.D.displayactuallyshow;installers,
endusersand maintainancepersonnelcaneasilyconfirm propersystemand controloperationinthefield andmakethe rightcorrective
adjustments when necessary.

5
Heat Demand signal Selector switch = External Demand
(a) - A Heat Demand signal is caused by either 24Vac applied to
terminals Heat Dem (5 and 6), or a 10K Zone Control connected
to terminals 10K Zone — Com Sen (27 and 28),or both.
(b) -A Heat Demand signal is either continuously present or; when
a 10K Zone Control is connected, a heat demand signal is
present only when the 10K Zone Control calls for heat.
Outdoor temperature cold enough to require heating
No heat demand signal
When the outdoor temperature is colder than the WWSD point, the control will leave WWSD. Whenever the control leaves WWSD,
the "WWSD" light will turn off and the control will continue to monitor the outdoor temperature, supply temperature and indoor
temperature (optional), but no further control action will take place until there is a Heat Demand signal.
The outdoor temperature will be continuously displayed if the "Outside Temperature" fixed display is selected.
With Heat demand signal
The "Heat Demand" and "Pump" lights will come on, the control will operate the system pump and calculate the target supply
temperature based on the requirements of the Heating Curve or the Minimum Supply setting, whichever is highest.
The "Target Supply" light will turn on and the target temperature will be continuously displayed if the "Target Supply" fixed display
is selected.
With boiler minimum setting higher than heating curve requirement
The"Minimum"and "Comb.air"lightswill comeonand thecontrolwillwaitfor 60seconds(to ensurethatthecombustionair damper
has had enough time to open). One or more "Stage" lights will come on and the control will stage on the boilers based on its PID
calculations.Theboilerswillfireuntilthesupplytemperaturereachestheminimumsettingplusthedifferentialsetting.Whenthispoint
is reached, the control will stage off the boilers based on its PID calculations and the "Stage" and "Comb. air" lights will be shut off
with the boilers and combustion air damper. The "Minimum" light will stay on and the control will continue to cycle the boilers and
combustion air damper to maintain the supply temperature at the Minimum setting.
The "Actual Supply" light will turn on and the supply temperature will be continuously monitored when the control is set for the
"Actual Supply" fixed display.
Occupied/Unoccupied Room Temperature function (no indoor temperature feedback)
The control will monitor the outdoor and supply temperatures. The Occupied or Unoccupied programmed room temperature settings
become the WWSD points. When the outdoor temperature is warmer than the Occupied room temperature setting, the control enters
WWSD.WhenswitchedintoUnoccupiedmode,the"UNOCC"displayelementwillreplacethe"OCC"displayelement,andthecontrol
will switch from operating at the Occupied room temperature setting to operating at the Unoccupied room temperature setting.
tekmar 10K Zone Control function
The control will monitor the indoor temperatures of all zones, as well as the outdoor and supply
temperatures,andshifttheHeatingCurve(andtheWWSDpoint)upordowntofineadjustthesystem
supplywatertemperatureforwhicheverzonerequiresthehottestsupplywater.TheinternalOccupied
and Unoccupied programs of the 258 are not functional.
OR
Selector switch = Perm. Demand
6785
Dem
91011 12 13
Stage
123
Stage
21
Dem Comb.
air
Heat
+
Auto
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Int. timer
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
26 27 28 29 30
UnO
Sw Com
Sen
10K
Zone
Sup
Sen Out Sen
10K
Zone
Control
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
OR
OR
Unoccupied mode
(a) – Unoccupied signal from the Internal timer
The DIP selector switch for the timer must be in the "Int. timer" position
When the control's Internal timer is active and a setback schedule is selected or programmed,
the control will enter the Unoccupied mode based on the program of the setback schedule.
Timer programming instructions are on page 16
(b) - Unoccupied signal from an external source
The DIP selector switch for the timer must be in the "Ext. timer" position
Connect (short circuit) terminals UnO Sw — Com Sen (26 and 28) together.
The Unoccupied room temperature setting becomes active. Any dry contact closure may be used to
switch into Unoccupied mode. Caution, dry contact only, there should be no voltage present.
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
26 27 28 29 30
UnO
Sw Com
Sen
10K
Zone
Sup
Sen Out Sen
+
WWSD function
When WWSD occurs, the "WWSD" light will come on, and the control will continue to monitor the outdoor temperature, supply
temperature and – if a 10K zone control is connected – indoor temperature. Whenever 3 days pass with the control in uninterrupted
WWSD, the pump will be cycled on for 20 seconds to help prevent it from seizing up. Caution: This control may start the pump
at any time. An approved, accessible electrical disconnect must be installed to allow safe maintainance procedures.
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset

Setpoint Operation (DIP selector switch must be in "Stpnt" position)
The 258 control must have the Reset/Stpnt selector switch set for "Stpnt", and must
receive a heat demand signal before it can operate in the setpoint mode .
When used for setpoint operation, the outdoor sensor has no function and need not be
installed. The "Outdoor Temperature" fixed display will show a null display (– – –).
Setpoint Demand signal Selector switch = External Demand
A Setpoint demand signal is caused whenever 24Vac is applied to terminals
Heat Dem (5 and 6).
Selector switch = Perm. Demand
A Setpoint demand signal is continuously present.
Occupied/Unoccupied Setpoint Operation
Thecontrolwill monitorthesupply temperature.TheOccupied orUnoccupiedprogrammedsetpointtemperaturesettingsbecomethe
target temperatures. When switched into Unoccupied mode, the "UNOCC" display element will replace the "OCC" display element,
and the control will switch from operating at the Occupied setpoint temperature setting to operating at the Unoccupied setpoint
temperature setting. Refer to the "Programming" section on page 15 for details on setting setpoint temperatures.
Unoccupied mode
(a) – Unoccupied signal from the Internal timer
The DIP selector switch for the timer must be in the "Int. timer" position
When the control's Internal timer is active and a setback schedule is selected or
programmed, the control will enter the Unoccupied mode based on the program
of the setback schedule.
Timer programming instructions are on pages 16 & 17
(b) – Unoccupied signal from an external source
The DIP selector switch for the timer must be in the "Ext. timer" position
Connect (short circuit) terminals UnO Sw — Com Sen (26 and 28) together.
The Unoccupied room temperature setting becomes active. Any dry contact
closure may be used to switch into Unoccupied mode.
Caution, dry contact only, there should be no voltage present.
Outdoor temperature cold enough for heating curve operation
The" Comb.air" lightwill comeon andthe controlwill waitfor 60seconds (toensurethatthecombustionairdamper hashadenough
timetoopen).Oneormore"Stage"lightswillcomeonandthecontrolwillstageontheboilersbasedonitsPIDcalculations.Theboilers
will fire until the supply temperature reaches the heating curve target temperature plus one half the Boiler Differential setting. When
this point is reached, the control will stage off the boilers based on its PID calculations and the "Stage" and "Comb. air" lights will be
shut off with the boilers and combustion air damper. The control will continue to cycle the boilers and combustion air damper to
maintain the supply at the target temperature.
Note: Whenever the boilers are turned off, the control will keep them off until at least the minimum time delay has expired (1 minute
to 5 minutes depending on degree of error).
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
OR
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
6
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
No Setpoint Demand signal
The control is essentially "on standby" at this point. The internal timer – if used – will continue to operate its various functions, but
no action will take place until a demand signal is present. Error messages will be displayed if an error occurs during this mode.
Refer to page 14 for a list of Error messages and their explanation.
When a Setpoint Demand signal is present
WhenswitchedintooperatingmodebyaSetpointDemandsignal,the"HeatDemand"and"Pump"lightswill comeonandthecontrol
will switch on the system pump. If the supply temperature is at least one half the Boiler Differential setting lower than the Setpoint
setting,The "Comb. air" lightwill come onand the controlwill wait for60 seconds (toensure that thecombustion air damperhashad
enoughtimeto open). One or more "Stage" lights will comeonand the control will stage the boilers onbasedon its PID calculations.
The boilers will fire until the supply temperature reaches the setpoint target temperature plus one half the Boiler Differential setting.
When this point is reached, the control will stage off the boilers based on its PID calculations, and the "Stage" and "Comb. air" lights
will be shut off with the boilers and combustion air damper. The control will continue to cycle the boilers and combustion air damper
to maintain the supply at the setpoint target temperature until the Setpoint Demand signal is removed.
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset

Caution: Improper installation and operation of this control could result in damage to equipment and possibly even personal
injury. It is your responsibility to ensure that this control is safely installed according to all applicable codes and standards.
Step One Getting ready
Check the contents of this package. If any of the contents listed are missing or damaged, please refer to the Limited Warranty and
Product Return Procedure on the back of this brochure and contact your Wholesaler or tekmar Sales Agent for assistance.
Type 258 includes: • One Control 258 • One Outdoor Sensor 070 • One Universal Sensor 071
• One Universal Sensor Enclosure 080 • One Data Brochure D 258 • One Data Brochure D 001
• One Application Brochure A 258
Other information available: • Essay E 001 • Essay E 002
ReadApplication BrochureA258 and select the correctApplication for your job.
Note: Carefully read the details of the Application, and the Sequence of Operation sections in all applicable brochures to ensure that
you have chosen the proper control, and you understand its functions within the operational requirements of your system.
Step Two Mounting the base
The control should be removed from its base by pressing down on the release clip in the wiring chamber and sliding upwards on the
control. The base is then mounted in accordance with the instructions in the Data Brochure D 001.
Step Three Rough-in Wiring
All electrical wiring terminates in the control base wiring chamber. It has standard 7/8" (22mm) knock-outs that will accept common
wiring hardware and conduit fittings. Before breaking out the knock-outs, check the wiring diagram and select those sections of the
chamber with common voltages, since the safety dividers will later prevent wiring from crossing between sections. Standard 18 to
22AWG solid wire is recommended for all low voltage wiring to tekmar controls. Heavier guage wire may not fit properly into the
terminal plugs, while lighter guage wire is too fragile and may also contribute too much resistance to the circuit.
Power should not be applied to any of the wires, during this rough-in wiring stage.
Step Four Electrical connection to the control
Power and output connections
The installer should test to confirm that no voltage is present at any of the wires.
Install the control into the base, sliding it down until it snaps into place.
All electrical connections are made directly to the terminal plugs.
Connect the 24Vac power supply from the secondary side of a 24Vac Class II transformer to
terminals Power C — R (1 and 2). Do not connect either of the transformer terminals to ground.
Connectthesystem pumpcircuitto terminals SystemPmp (3and4). These terminalsleadto a10amp
dry relay contact which closes when the control requires system pump operation.
Note: The258isapprovedforlowvoltageonly(Maximum24Vac).Thesystempumpmustbeswitched
through an isolation relay approved for the line voltages required to operate the pump.
7
Installation
Maximum 24 Volts
Connect the combustion air damper circuit to terminals Comb. air (7 and 8). These
terminals lead to a 10 amp dry relay contact which closes when the control requires
combustion air damper operation.
Note: The 258 is approved for low voltage only (Maximum 24Vac). If the combustion air
damper operates on line voltage, it must be switched through an isolation relay.
6785
Dem
91011 12 13
Stage
123
Stage
21
Dem Comb.
Air
Heat
1234
CR
Power PmpPmp System
• Install the Outdoor Sensor 070, and the Universal Sensor 071 according to the instructions in the Data Brochure D 001 and run the
wiring back to the control.
Option: A 10K tekmar Zone Control can also be connected (purchased separately) .
• Install the wiring from other system components; Boiler(s), Pump relay, Heat Demand or Setpoint Demand circuits to the base.
• Install a 24Vac Class II transformer with a minimum 5VA rating close to the control, and run the wiring from the transformer to the
base. A Class II transformer must be used. Do not connect any of the transformer terminals to ground .
1234
CR
Power PmpPmp System

8
type 258
Do not apply
power here!
Maximum 24 Volts
10A
Safety Divider
24
Vac
120
or
240
Vac
External 24Vac
60Hz class II
transformer
System Pump
Relay
closes to turn on
System Pump
10K Zone
Control
(optional)
Unoccupied
Switch (optional)
to switch control to
Unoccupied mode
Outdoor
Sensor
070
Supply
Sensor
071
26 27 28 29 30
UnO
Sw Com
Sen
10K
Zone
Sup
Sen Out Sen
6785
1234
Dem
10A
910
10A
11 12
10A
13 14
10A
15 16
Safety Divider
Stage
1234
Stage Stage Stage
2134
Dem
10A
17 18
10A
19 20
10A
21 22
8A
23 24
Stage
5678
Stage Stage N/C
6578
CR
Power PmpPmp System Comb.
air
25
8
Com N/O
Boiler Relays
close to turn on boilers
10A
Combustion
air Relay
closes to operate
Combustion air damper
Heat Demand
Apply a 24Vac signal
to request heat
to the system
Heat
Connectthe stage1 boilercircuit toterminals Stage1 (9
and 10). These terminals lead to a 10 amp dry relay
contact which closes when the control requires boiler
operation.Repeatthisstepwiththecorrect terminalsfor
eachadditionalstage.Boilerswith24Vaccontrolcircuits
can be switched directly through the control. If higher
voltages are used, isolation relays must be added.
891011 12 13 14 15 16
Stage
1234
Stage Stage Stage
2134
17 18 19 20 21 22 23 24
Stage
5678
Stage Stage N/C
6578
b.
r
25
8
Com N/O
Powered input connections
Ifa24Vacexternal HeatDemand signalisused,(zonevalveendswitches, etc.)connect
the wiring from the Heat Demand circuit to terminals Heat Dem (5 and 6). When 24Vac
is applied to these terminals, the control will recognize a "call for heat" from the system.
DIP switch must be set to "Reset"
If a 24Vac Setpoint Demand signal is used, (aquastat, etc.) connect the wiring from the
SetpointDemandcircuittoterminals HeatDem (5and6).When24Vacisappliedtothese
terminals, the control will recognize a "call for Setpoint temperature" and switch into
Setpoint mode. DIP switch must be set to "Stpnt"
6785
Dem
91011 12 13
Stage
123
Stage
21
Dem Comb.
air
Heat
Sensor and unpowered input connections
Power should never be applied to these terminals.
Damage to the control will result.
Connect the two wires from the Outdoor Sensor 070 to terminals
Com Sen — Out Sen (28 and 30).
Connect the two wires from the Supply Sensor 071 to terminals
Com Sen — Sup Sen (28 and 29).
Do not apply power here!
26 27 28 29 30
UnO
Sw Com
Sen
10K
Zone
Sup
Sen Out Sen
26 27 28 29 30
UnO
Sw Com
Sen
10K
Zone
Sup
Sen Out Sen
Option: Indoor temperature feedback, tekmar 10K Zone Control Only
Connect the two wires from a tekmar 10K Zone Control to terminals
10K Zone — Com Sen (27 and 28).
Option: Occupied/Unoccupied switch input, when not using Internal timer
Connect the two wires from the Occupied/Unoccupied dry contact switch
(timer, relay, etc.) to terminals UnO Sen — Com Sen (26 and 28).
26 27 28 29 30
UnO
Sw Com
Sen
10K
Zone
Sup
Sen Out Sen
26 27 28 29 30
UnO
Sw Com
Sen
10K
Zone
Sup
Sen Out Sen
Electrical connections to the terminal plugs of the 258 control. Control relays are shown in "power down" condition.
Note: This is not a Wiring Diagram. For a detailed wiring schematic of
your specific application, refer to the Application Brochure A 258.

Step Five Testing the wiring
Caution
• These tests are to be performed using standard testing practices and
procedures and should only be carried out by properly trained and
experienced persons.
• Before applying power to the control for testing, each terminal plug must be
unplugged from its header on the control. Pull straight down to unplug.
• A good quality electrical test meter, capable of reading from at least
0 — 200 Volts AC, and at least 0 — 1,000,000 Ohms, is essential to properly
test this control.
Test the sensors
• These tests must be made before turning on the power supply, and with the
terminals unplugged.
• The sensors are to be tested according to the instructions in Brochure D 001.
Test the power supply
Make sure exposed wiring or bare terminals are not in contact with any other wires or grounded surfaces. Turn on the power to the
transformer and use an AC voltmeter to measure the voltage between terminals Power C — R (1 and 2). 22 to 26 Volts AC should be
measured at these terminals.
Test the powered inputs
If an external Heat Demand or Setpoint Demand signal is used, power up the Heat or Setpoint Demand circuit and supply a Demand
signal to the control. Use an AC voltmeter to measure the voltage between terminals Heat Dem (5 and 6). 22 to 26 Volts AC should be
measured at these terminals.
Ifasystempumpcircuitisconnectedtothe SystemPmp (3and4)terminals; makesurepowertothecircuitisoffandinstallajumper
in the terminal plug between terminals (3 and 4). When the circuit is powered-up, the pump should operate. If it does not come on,
check the circuit wiring for errors and ensure that it is powered up and the voltage is correct. Check the devices in the circuit (pump,
switchingrelay, etc.) forfaults. Ifthe pump operatesproperly when thecircuit is poweredup, disconnect thepower, remove thejumper
and proceed to the next step.
If a combustion air damper circuit is connected to the Comb. Air (7 and 8) terminals; make sure power to the circuit is off and install
ajumperintheterminalplugbetweenterminals(7and8).Whenthecircuitispowered-up,thecombustionairdampershouldoperate.
Ifitdoes notcomeon, checkthecircuit wiringforerrorsandensurethatitispoweredupand thevoltageis correct.Checkthedevices
inthecircuit(damper motor,switchingrelay,etc.)forfaults. Ifthedamperoperates properlywhenthecircuitispoweredup,disconnect
the power, remove the jumper and proceed to the next step.
Makesurepower to the Stage 1boilercircuit is off and installajumper in the terminal plugbetweenthe Stage1 (9and10) terminals.
When the circuit is powered-up, the boiler should operate. If it does not come on, check the circuit wiring for errors and ensure that
it is powered up and the voltage is correct. Check the devices in the circuit (limits, flow switches, etc.) for faults. If the boiler operates
properly when the circuit is powered up, disconnect the power, remove the jumper and check the remaining stages in the same way.
If all stages operate correctly, proceed to the next step.
9
Connect the control
Turn the power off and make sure all test jumpers have been removed from
the plugs.
Connect the plugs to the control by carefully aligning them with their respective headers
and pushing them upwards into the headers. The plugs should snap firmly into place.
The control wiring is now complete and has been tested. The control is ready for set-up
and operation. Terminal plug pushed into
its header on the control
26 28
27 29 30
Com
Sen
UnO
Sw
Out
Sen
10K
Zone
Sup
Sen
Terminal plug disconnected
from its header on the control
26 28
27 29 30
Com
Sen
UnO
Sw
Out
Sen
10K
Zone
Sup
Sen
Caution
The tekmar Eight Stage Boiler Control 258 is an operating control and is not certified or intended for
useasasafetydevice. Undernocircumstancesshouldsafetylimitdevicesbeleftdisconnectedafter
installation of this control. The installer shall check all applicable code requirements and obtain
necessary inspections to ensure that the installation is in compliance with those requirements.
This Control operates remote devices such as pumps and combustion air dampers as well as the
boilers, and these devices may be started by the control at any time. Installers must install approved
electrical disconnects at these locations to allow these devices to be serviced safely.

10
Step Six Essential control settings
To obtain the best operation from a reset control, it is important to measure the system supply temperature as accurately
as possible. Whenever the control receives a heat demand signal, the system pump must be operated to maintain
continuous water flow past the supply temperature sensor.
For specific application details refer to Application Brochure A 258.
AmoredetailedtechnicaldescriptionoftheeffectofcontrolsettingsonoverallsystemoperationisdescribedinthetekmarEssay,E 002.
Reset operation
Stpnt — Reset switch
When the boilers are used in a heating system and the supply temperature is to be
controlled on an outdoor reset schedule (Heating Curve), this switch must be set
to "Reset".
Programming the control for Occupied/Unoccupied room temperatures and setback
schedules will be covered in the "Programming" section starting on page 15.
Heat Demand switch
When the heating system uses zone valve end switches or some other means of
delivering an external heat demand signal to terminals Heat Dem (5 and 6), set this
selectorswitchto "ExternalDemand"and thecontrolwill beenabledwhenitreceives
a24Vacsignal from the heat demand circuit. Ifan external heat demand signal is not
used, set the switch to "Permanent Demand".
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Heating Curve
As outdoor temperatures drop, heat losses from a building become greater and the
heatingsystemsupplywatertemperaturemustberaisedtomaintainaconstantroom
temperature.Theheatingcurvevaluedescribeshowmanydegreesthesupplywater
temperature is raised for a one degree drop in outdoor temperature. The supply
temperaturestartstoincreasewhentheoutdoortemperaturefallsbelowtheWWSD
point. To calculate the correct setting for the Heating Curve, use the following
formula.
Outdoor air temperature
Supply water temperature
50
(10) 30 (-1) 10 (-12) -10°F (-23)°C
110
(43)
70
(21)
70
(21)
90
(32)
210
(99)
170
(77)
150
(65)
130
(54)
190
(88)
3.6 3.0 2.4 2.0 1.6
0.8
0.4
1.0
0.6
90
(32)
50°F
(10)°C
Heating
Curve
WWSD
Point
1.2
For more information regarding the Heating Curve, refer to page 2 of this brochure.
Iftheactualdesign supplywatertemperatureforasystemisunknown,a trialsetting
can be calculated using these typical supply temperatures:
•Fancoils…180°to210°F(82°to99°C) •Baseboards …160°to190°F(71°to88°C)
• Radiant floors …100°to 130°F (38°to 54°C).
160°F - 70°F
70°F - 5°F90°F
65°F
design supply temperature – room temperature
room temperature – design outdoor temperature
Heating Curve =
For example: • design outdoor temperature = 5°F (-15°C)
• room temperature = 70°F (21°C)
• design supply temperature = 160°F (71°C)
Heating Curve = = = 1.4
Setpoint operation
Stpnt — Reset switch
When the boilers are used to maintain the supply temperature at a setpoint, set this
switch to "Stpnt".
Programming the control for Occupied/Unoccupied setpoint temperatures and set-
back schedules will be covered in the "Programming" section starting on page 15.
Setpoint Demand switch
End switches, aquastats or some other means of delivering an external setpoint
demand signal can be used to bring 24Volts to terminals Heat Dem (5 and 6) when
thecontrolisusedasasetpointcontrol.Thisselectorswitchshouldbesetto"External
Demand" and the control will be enabled when it receives the 24Vac signal. If an
external setpoint demand signal is not used, set to "Permanent Demand".
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
0.4
2.0
3.6
Heating Curve
Settings

11
Common Settings
Stage 1, 2, 3, 4, 5, 6, 7, & 8 Auto or Off switch
When a stage switch is set to "Auto", that particular stage becomes active and its
boilerisavailable for operation. If the stage switch is "Off",thecontrol will ignore that
stage and not turn it on.
Rotate switch
When this switch is set to "Rotate", the firing order of the stages is changed to even
out wear and tear on the boilers. Whenever one stage accumulates 48 hrs more
running time than the others, it will be rotated to be the last boiler fired and the boiler
withthe leastamountof runningtimewill becomethe lead boiler.Whenever theTest
button is pushed, the control automatically re-ranks the firing sequence based on
accumulatedrunningtimes.WhentheRotateswitchissetto"Off",thefiringorderwill
always stay the same; 1,2,3,4,5,6,7,8 to stage on, and reverse order to stage off.
Fixed lead switch
When the boilers are to be rotated and this switch is set to "Fixed lead", the stages
arerotatedasdescribed abovewiththeexceptionthatStage1willalways bethefirst
boilertofireandthefirstboilertostageoff.Thisfeatureiscommonlyusedwhenahigh
efficiency lead boiler is used in conjunction with mid efficiency boilers to increase
overallheatingplant efficiencies,orwhentheboiler closesttoa chimneyneedstobe
fired first in order to establish draft in the chimney.
Lo-Hi fire switch
When boilers are to be rotated and Lo-Hi fire boilers are used, the stages must be
rotatedinsuchawayastopreventpossibleHighfirestartsandmixingupofthestages
betweenboilers. Whenthis switchisset to"Lo-Hi fire",the stages rotateas Lo-Hifire
pairs (1 & 2 and 3 & 4, etc.) and the hours of use are calculated based on the Lo fire
run times. In addition, the control will not allow a Hi fire stage to operate if its
corresponding Lo fire stage DIP switch has been turned off. (ie. if Stage 1 is turned
off, stage 2 will not be allowed to fire and the control will move on to 3 & 4)
Fixed last switch
Whentheboilersaretoberotated andthisswitchissetto"Fixed last",thestagesare
rotated as described above with the exception that Stage 8 will always be the last
boilerto fireandthe firstboiler tostageoff. Thisfeature iscommonlyused tooperate
a diverting valve which will allow Domestic Hot Water boilers to be switched over to
assist the heating boilers during peak load times.
Int. timer switch
The 258 control has an internal timer – programmed using the LCD display and
keypad – that can be used to switch up to two Occupied/Unoccupied events per day
on a 7 day basis.
Details on the operation of this timer can be found in the "Programming" section on
page 15.
Ext. timer switch
The 258 control can be switched into the Unoccupied mode by an external signal
whenadrycontactclosureoccursbetweenterminals UnOSw—ComSen (26&28).
Minimum Supply Temperature
This dial should be set according to the requirements specified by the boiler
manufacturer. Many boilers require a minimum operating temperature to prevent
corrosionfromfluegascondensation.Thecontrolraisesthesupplytemperaturetothe
Minimum setting when the outdoor temperature drops below the WWSD point, and
holdsitthereuntiltheoutdoortemperaturebecomescoldenoughtorequireoperation
on the heating curve.
Note: Many boiler manufacturers requires a minimum return temperature to their
equipment. In systems where this is a strict requirement, the minimum supply
temperature setting should be set to the recommended return temperature plus the
boiler ∆ T under full load conditions.
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Minimum
120°F
Off 170
80

12
Test button
The control can be made to cycle through a test routine whenever the Test button is pushed. The
test can be halted at certain times by pushing the button a second time. For details of the test
routine, refer to the description starting on the next page.
Test
Boiler Differential and Time Delay
The Boiler Differential adjustment sets how much the actual
supplywatertemperaturemaydeviatefromthe desiredtempera-
ture before stages are turned on or off, and is determined by the
flow rate past the supply sensor relative to the amount of heat
producedby eachstage.To preventshort operatingcyclesof the
boilers the control has a delay of at least 1 minute between firing
cycles. On an installation where flow rates are known, the Boiler
Differential can be calculated as follows:
Desired temperature
this example
160°F(71°C)
Temperature WarmerCooler
Time
Differential
this example
10°F(5°C)
165°F(74°C)
155°F(68°C)
Temperaturefall
Staging
OFF ON
Temperaturerise
Boiler Differential =
For example: = 10°F (6°C)
Btu/hr
US GPM x 500
100,000 Btu/hr
20 US GPM x 500 Trial setting = 22°F if
flow rates are unknown
22°F
242
Boiler
Differential
All boilers will eventually turn on when the temperature falls and stays 5°F (3°C) below the desired temperature. Delays of 1 to
5minutes forstaging ondepend on the degree of control error(P+I+D). Asthe temperaturerises towithin the differential range,
noboilersarestagedonoroff.Allboilerswilleventuallyturnoffwhenthetemperaturerises andstays 5°F(3°C)abovethedesired
temperature. Delays of 8 seconds to 3 minutes for staging off depend on the degree of control error.
Settinga boilerdifferentialformodularboilers isoften complicated
by the fact that flow rates and heating loads may vary widely, and
attimes boileroutputsmaynotbe balancedto theload. Observing
the "Target Supply" fixed display while the boilers are staging can
assist the user in understanding system flow and boiler problems.
The ideal control reaction occurs when the target supply tempera-
ture remains constant or only changes slightly during the staging
process, indicating a well balanced and constant – or slowly
changing – load vs. output in the system.
If the target supply temperature decreases rapidly when a boiler
comes on, it indicates a heavy derivative action by the control in
response to a rapid supply temperature increase. This type of
action typically indicates a condition where the boiler output is far
inexcessoftheload,asituationthatisusuallytheresultofasystem
that is operating with only a few zones open (decreased load).
Settingawiderdifferentialandensuringaminimumfixedload(wild
loops) can help minimize this problem.
If the target supply temperature increases rapidly , it indicates a
heavy derivative action by the control in response to a rapid load
increase.Thistypeofactiontypicallyindicatessituationswherethe
loadisnotfinelydivided(afewlargezones)andisusuallytheresult
of one large zone opening – or a system coming out of setback –
anddelivering coldwatertotheboilers (increasedload). Typically,
this will cause many or all of the boilers to be staged on with
minimumdelay,whichisthecorrectcontrolactionforthesituation.
If the load fluctuates rapidly and repeatedly from heavy to light,
some instability may result in the staging process as the control
tries to bring on many boilers at once and then shut them off again
whenthe loadsuddenlydecreases.Thetarget temperaturewill be
constantly increasing and decreasing. Setting a wider differential
will help to stabilize the control action in many of these cases.
If the target supply temperature slowly and continually climbs, it
indicates that the supply temperature is not rising to the target
temperature. The control will continue to request more and more
boilers until the supply temperature rises sufficiently to reduce the
controlerror.Thisproblemiscalled"ResetWindup"andcanoccur
in systems where: (a) the boilers are undersized, (b) flow is
interrupted – without removing the heat demand – to the point
where the supply sensor cannot detect the supply temperature
increase, or (c) where the supply sensor is incorrectly placed – ie.
on the wrong pipe or on the return of a system with very long runs.
The problem must be identified and corrective action taken.
If the target supply temperature slowly and continually decreases
after the boilers have been shut down, it indicates that the supply
temperatureishotterthanthetargettemperature.Thiscanhappen
insystemswithhighmassboilerswheretheflowhasbeenstopped
withoutusingtheheatdemandinputtothecontrol ,andconvection
from the still hot boiler continues to heat the supply sensor. If the
heatdemandinputisusedtoshutthesystemdown,thecontrolwill
ignore the sensor reading during the off cycle.
Overheatingof buildings inwarm weather willoccur where minimumboiler temperatures are
required, unless the building has either a mixing system to reduce system supply water
temperaturestobelowboilerminimums,orsomesortofroomtemperaturecontrolandzoning
system. Zone controls from tekmar, when used in these applications, will provide room
temperature feedback information to this control, allowing it to shift the heating curve for
maximum comfort and energy savings.
TypicalMinimumBoilerOperatingTemperatures: •SteelTubeBoilers …140°to180°F(60°
to 82°C) • Cast Iron Boilers …130°to 150°F (54°to 66°C) • Copper Tube Boilers …105°to
150°F (41°to 66°C) • Condensing or Electric Boilers …Off
Note: If the control is being operated in the setpoint mode and a boiler minimum setting is
selected,the userwillbe unableto programasetpoint lowerthan theminimumtemperature
plus 1/2 of the Boiler Differential setting. If the minimum dial is set higher than the setpoint
less1/2 theBoiler Differential,the setpointwillautomatically beraised as thedial isturned
up. If the dial is then turned back down, the setpoint will have to be re-programmed.
Outdoor air temperature
Supply water temperature
50
(10) 30 (-1) 10 (-12) -10°F (-23)°C
110
(43)
70
(21)
70
(21)
90
(32)
210
(99)
170
(77)
150
(65)
130
(54)
190
(88)
3.6 3.0 2.4 2.0
0.8
0.4
1.0
0.6
90
(32)
50°F
(10)°C
Heating
Curve
1.2
Minimum Supply
Setting 130°F
WWSD
Point
70°F
1.6

Pump
The control returns to Fixed
Display #1, showing the actual
supply temperature, and will
then be in Operating Mode
Press
test
button
S SMWTFT
Stage 2
Setpoint
Actual
Supply
Target
Supply
F
S
TEMP
OCC
SMWTFT
Auto
Stage
1
2 3 4 5 6 7 8
Off
123456789
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Off
123456789
Stpnt
Reset
Rotate
Off
123
Auto
Stage
1 2 3 4 5 6 7 8
Off
123456789
Stpnt
Reset
Rotate
Off
123
Auto
Stage
1 2 3 4 5 6 7 8
Off
123456789
Stpnt
Reset
S SMWTFT
Comb. air
Turns off
after 10
seconds
On for
10 seconds
unless
paused
Stage 1
Test
S SMWTFT
The Control Must
Show Fixed Display
#1, 2, 3 or 4
See page 3
Heat
Demand
Stays on
through
routine
1
2
Option for 5 minute pause –
pause Stage 1
Stage One – Off
Stage Two – Off
Pump
Heat
Demand
Pump
S SMWTFT
Stage 1
S SMWTFT
Stage 2
Optional pause in
test routine is
allowed only when
there is a Heat
Demand signal
Press Test button
"Test" light will
flash and pump or
boiler will run for 5
minutes or until
Test button is
pushed again
Option for 5 minute pause –
pause Stage 2
Option for 5 minute pause –
pause pump
The sequence repeats
for all 8 stages
?Leave
pump on?
?Test stage
one?
?Test stage
two?
Option for 5 minute pause –
pause combustion air damper
Combustion air
damper opens and
remains open
through test routine
PRGM
FC
S
TEMP
TIME
USE
ROOM OUTSIDE
AMPM
UNOCC
OVR
SMWTFT
1
2
Setpoint
Actual
Supply
Target
Supply
Step Seven
Operational test of control functions - Test button
TheEightStageBoilerControl258hasaTestbuttonwhichcanbeused
to test the main control functions any time there is a "fixed display"
showing.WhentheTestbuttonispushed,thecontrolautomaticallyruns
through this test procedure. If a fault is detected, the display shows an
Error Message. These Error Messages are listed on page 14.
Full Display and red temperature indicator lights on
At the start of each test routine and on power-up, the full display and all
oftheredtemperature indicatorlightsareswitchedonforapproximately
5 seconds. During this time the control searches for sensor faults and,
if no faults are found, proceeds to the next step. If a sensor fault exists,
the control exits the test routine and the display will show an Error
Message. See page 14.
Power, Test, Comb. air light on - Display = "C A"
The control signals the combustion air damper to open (whether there
is one connected or not) and will wait for 10 seconds before:
(a) — proceeding to the next step, OR (b) — During the 10 seconds, if
thereisaHeatDemandorSetpointDemandsignaland theTestbutton
is pressed, the test routine will be halted, the "Test" light will flash, and
the control will be held in a pause mode for up to 5 minutes. During this
time, the combustion air damper will remain open. After the 5 minutes,
the control will automatically exit the test routine and enter the normal
operating mode. If there is no Heat Demand, the control will not allow
apauseandwillproceedtothenextstepofthetestroutine.Pushing the
Testbuttonduringthe5minutepause will allow the control to proceed to
the next step of the test routine immediately. The open signal (and
"Comb. air" light) remains on for the duration of the test routine.
Power, Test, Comb. air, Pump light on - Display = "P"
The control turns on the system pump for 10 seconds and:
(a) — proceeds to the next step, OR (b) — During the 10 seconds, if
thereisaHeatDemandorSetpointDemandsignaland theTestbutton
is pressed, the test routine will be halted, the "Test" light will flash, and
the control will be held in a pause mode for up to 5 minutes. During the
5 minutes, the System pump will remain on. After the 5 minutes, the
control will automatically exit the test routine and enter the normal
operating mode. If there is no Heat Demand, the control will not allow
apauseandwillproceedtothenextstepofthetestroutine.Pushing the
Testbuttonduringthe5minutepause will allow the control to proceed to
the next step of the test routine immediately.
Power, Test, Comb. air, Pump , Stage 1 light on - Display ="b 1"
IfthereisaHeatorSetpointDemand,thesystempumpwillremainon.
The control will turn on stage 1 for 10 seconds and:
(a)—proceedtothenextstep, OR (b)—Duringthe10seconds, ifthere
isaHeatorSetpointDemandsignal,andtheTestbuttonispressed, the
test routine will be halted, the "Test" light will flash, and the control will
beheldinapausemodeforupto5minutes.PushtheTestbuttonduring
the 5 minute pause and the control will proceed to the next step
immediately. During the 5 minutes, the Pump and Stage 1 will remain
on.Afterthe5minutes,thecontrolwillautomaticallyexitthetestroutine
and enter the normal operating mode. If there is no Heat or Setpoint
Demand,thePumpwillnotberunning,thecontrolwillnotallowapause
and will proceed to the next step of the test routine. The control will
repeatthis step for each ofthestages that are switched to"Auto"at the
DIP switches, and after the last stage is tested will exit the test routine
and enter normal operating mode.
Note:
Wheneverthecontrolexitsthetestroutine,thereisana4seconddelay
beforethecontrolcanbe made to re-enter the test routine. Pushingthe
Testbuttonduringthis4secondperiodwillhavenoeffectonthecontrol.
Power light on — Test light off
The controlhas exitedthetestroutine,enteredtheoperatingmodeand
willfunctionaccordingtothesequenceofoperationdescribedonpages
4 – 6. One or more of the other indicator lights may also be on. Refer
to pages 4 - 6 for a description of the indicator lights under operating
conditions.
13
TEST ROUTINE – AUTO/MANUAL
Testing the Control Functions
TEST ROUTINE

ERROR MESSAGES
If a sensor fault occurs during normal
operation or during the test routine, the word
"Err" will appear in the display screen and the
display will flash back and forth between
"Err" and one of the error codes listed below.
The display flashes between "Err" and "S 1"
Check the outdoor sensor and the wiring from the
terminal plug to the sensor.
With this error, the control will operate the boilers as if
the outdoor temperature was -8°F (-22°C)
S SMWTFT
S SMWTFT
S SMWTFT
S SMWTFT
S SMWTFT
OUTDOOR SENSOR — SHORT CIRCUIT
S SMWTFT
S SMWTFT
S SMWTFT
S SMWTFT
S SMWTFT
The display flashes between "Err" and "O 1"
Check the outdoor sensor and the wiring from the
terminal plug to the sensor.
With this error, the control will operate the boilers as if
the outdoor temperature was -8°F (-22°C)
OUTDOOR SENSOR — OPEN CIRCUIT
The display flashes between "Err" and "S 2"
Check the supply sensor and the wiring from the
terminal plug to the sensor.
With this error, the control will shut down the boilers,
close the combustion air damper but leave the pump on.
SUPPLY SENSOR — SHORT CIRCUIT
The display flashes between "Err" and "O 2"
Check the supply sensor and the wiring from the
terminal plug to the sensor.
With this error, the control will shut down the boilers,
close the combustion air damper but leave the pump on.
SUPPLY SENSOR — OPEN CIRCUIT
The display flashes between "Err" and "S 3"
Check the wiring from the terminal plug to the
10K Zone Control.
With this error, the control loses its indoor temperature
feedback and operates at the Occ or Unocc settings.
ZONE CONTROL— SHORT CIRCUIT
Step Eight Troubleshooting
As in any troubleshooting procedure, it is important to isolate a
problem as much as possible before proceeding. The 258 can
help the user in three significant ways.
(1) — The Error Messages can pinpoint certain problems and
eliminate others.
(2) — Cycling the control through the test routine allows the
operation of the various components to be examined
individually and in a systematic way to greatly simplify
troubleshooting.
(3) — The display can show outdoor, actual supply and target
supply temperatures, and the LED system status lights
displaytheoperationofthevarioussystemcomponents.
A competent troubleshooter can locate system faults
without having to go any further than observation of
these important temperature and status indicators.
Ifafaultoccursduringoperatingmodeorduringthetestroutine
and the control is flashing an Error Message, identify the fault
from the look-up table on the right side of this page and then
follow standard testing procedures to confirm the problem.
If you suspect a wiring fault, return to steps four and five and
carefully check all external wiring and wiring connections.
Notes:
Ifthe Outdoor Sensordevelopseither a shortcircuit or an open
circuit, the control is programmed to calculate the outdoor
temperatureat-8°F(-22°C)andcontrolthesupplytemperature
accordingly.
The control is programmed to shut the boilers down before the
supply temperature can reach a maximum allowable supply
water temperature of 248°F (120°C).
If the Supply Sensor develops either a short circuit or an open
circuit, the control is programmed to shut down the boilers and
run the system pump to prevent overheating.
If a Zone Control input becomes shorted out, the Occupied or
Unoccupied setting will become active.
Afteranyrepairhasbeencompleted,presstheTestbutton
to allow the control to cycle through the test routine. This
will allow you to confirm that correct operation has been
restored and that wiring connections are undisturbed.
Step Nine Before you leave
Make sure wiring dividers are installed in the proper locations
between compartments having different voltages.
Installthe wiringcover overthewiring chamberand secureit to
thebasewiththetwoscrewsprovided. Placethefrontcoveron
thecontroltocoverthesettingdialsandsnapitintoplace. Install
a lock if security is required.
Place this brochure, and all other brochures relating
to the installation, in the protective plastic bag sup-
pliedwiththecontrol. Placethebaginaconspicuous
location near the control for future reference, as
programminginstructionswill need to beaccessible
for future users.
Itisimportant to explain the operationandmaintainance of this
control and of the system to the end user and anyone else who
may be operating the system.
Error Messages
14
ERROR MESSAGES

15
TEMPERATURE MENU – VIEWING/PROGRAMMING
TEMPERATURE MENU
Setpoint
Actual
Supply
Target
Supply
F
S
TEMP
OCC
SMWTFT
ACTUAL SUPPLY
Fixed display #1,
continuous
readout
Time-out displays will automatically revert to Stable
display #1 after 20 seconds of no keypad action
Fixed displays will deliver continuous readout
unless manually changed by keypad command
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
S
TIME
PM
OCC
SMWTFT
1
TIME/DAY MENU
The control cycles through the "BOILER HOURS OF
USE" display for 20 seconds and then times-out (this
example shows that Boiler #1 has 16,304 hours)
PRGM
S SMWTFT
PROGRAM MENU
S
USE
SMWTFT
S
USE
SMWTFT
BOILER HOURS OF USE MENU
S
USE
SMWTFT
Fixed display #4,
continuous
readout
Time-out
display
Stage
number 1 to 999
thousand
hours
0 to 999
hours
Auto-cycle,
time-out display
?
To prevent a display time-out while programming or
viewing, press and hold the "Override" button.
Which mode
is selected?
hours
of
use
Menu Item Override
Menu Item Override
Menu Item Override
MENU ACCESS – VIEWING
TARGET SUPPLY
F
S
TEMP
OCC
SMWTFT
Setpoint
Actual
Supply
Target
Supply
ACTUAL SUPPLY
Setpoint
Actual
Supply
Target
Supply
F
S
TEMP
OCC
SMWTFT
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
F
S
TEMP
SMWTFT
F
S
TEMP OUTSIDE
OCC
SMWTFT
OUTSIDE
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
Setpoint
Actual
Supply
Target
Supply
F
TEMP
UNOCC
F
S
TEMP ROOM
UNOCC
SMWTFT
When "OCC" is flashing
press or to lower or
raise occupied setpoint
S SMWTFT
When "UNOCC" is flashing
press or to lower or
raise unoccupied setpoint
When "°F" or "°C" is flashing
press or to change to the
opposite temperature scale
When "UNOCC" is flashing
press or to lower or
raise unoccupied room temp.
When "OCC" is flashing
press or to lower or
raise occupied room temp.
Fixed display #1,
continuous
readout
Fixed display #2,
continuous
readout
Fixed display #3,
continuous
readout
Time-out displays will automatically revert to Fixed
display #1 after 20 seconds of no keypad action
Fixed displays will deliver continuous readout
unless manually changed by keypad command
Time-out displays
Time-out displays
Time-out display
?
F
S
TEMP ROOM
SMWTFT
ROOM
Setpoint
Actual
Supply
Target
Supply
F
S
TEMP
OCC
SMWTFT
SETPOINT
To prevent a display time-out while programming
or viewing, press and hold the "Override" button.
Which mode
is selected?
OCC
Menu Item Override
Menu Item Override
Menu Item Override
Menu Item Override
Menu Item Override Menu Item Override
Menu Item Override Menu Item Override
PROGRAMMING

16
PROGRAMMING
TIME/DAY MENU – PROGRAMMING
The control cycles through the Stage Two "BOILER HOURS OF USE"
display for 20 seconds and then times-out. If "Item" is pressed
within the 20 seconds, the control advances to Stage Three, etc.
S
USE
SMWTFT
S
USE
SMWTFT
BOILER HOURS OF USE
S
USE
SMWTFT
Stage
number
One
16,304 hrs.
1 to 999 thousand hours
0 to 999 hours
Auto-cycle,
time-out display
S
USE
SMWTFT
S
USE
SMWTFT
S
USE
SMWTFT
Stage
number
Two
16,289 hrs.
0 to 999 hours
Auto-cycle,
time-out display
The control cycles
through the Stage
One "BOILER
HOURS OF USE"
display for 20
seconds and then
times-out.
If "Item" is pres-
sed within the 20
seconds, the control
advances to display
Stage Two hours.
Menu Item Override
Menu Item Override
BOILER HOURS OF USE MENU – VIEWING
OR
Fixed display #4, after
power-up
TIME/DAY
Fixed display #4, in use
(48 hrs. battery back-up)
TIME/DAY
S
TIME
AM
SMWTFT
Press or to increa-
se or decrease minutes
S
TIME
SMWTFT
Press or to increa-
se or decrease hours
Time-out
Displays
Must be set to
"Int. timer"
Auto
Stage
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Fixed last
Int. timer
Lo-Hi fire
Fixed lead
Rotate
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
1
OCC
Full Display Flashing
(Programming Required)
S
TIME
SMWTFT
S
TIME
AM
SMWTFT
OCC
1
S
TIME
AM
SMWTFT
Menu Item Override
Menu Item Override
Menu Item Override
Press or
to change
the day
pointer
PROGRAM MENU – VIEWING
Must be set to
"Int. timer"
Auto
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Int. timer
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
PRGM
S SMWTFT
PRGM
S SMWTFT
S
PM
UNOCC
SMWTFT
PRGM
S
AM
OCC
SMWTFT
1
OR
To advance to viewing only
of program, just wait 5
seconds and current "day"
will be indicated
Press "Item" and
advance to "P 1"
PRGM
S SMWTFT
Note: These program displays are "Time-out" displays
Repeat to advance to "P 2, 3, 4, 5 or 6"
A flashing underscore indicates an
active program. Wait 20 seconds to
time-out to "ACTUAL SUPPLY" fixed
display or Press "Menu" to advance to
viewing "BOILER HOURS OF USE"
and other menu selections
Press or to view
different days or press
"Item" repeatedly to scroll
through each time and
temperature in sequence
PRGM
S SMWTFT
PRGM 1
PRGM
S
PM
UNOCC
SMWTFT
2
PRGM
S
PM
OCC
SMWTFT
2
OR
Menu Item Override
Menu Item Override
Menu Item Override
Menu Item Override
Menu Item Override
Menu Item Override
Menu Item Override
Menu Item Override
PROGRAM MENU – "P 1 TO P 6 PROGRAMMING
To Select a Program:
Choose the program you would like to enter (page 18)
Advance to "PROGRAM MENU" and press "Item"repeatedly
until that program indicator is displayed
Menu Item Override
PRGM
S SMWTFT
PRGM
S SMWTFT
PRGM
SSMWTFT
Press and at the same time
and hold for at least one second
The program has now been
selected. Refer to PROGRAM
MENU - VIEWING above.
The word "SEL" will appear
until the and are released,
and then the display will
advance to the viewing stage
of that program.

17
Must be set to
"Int. timer"
Auto
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Int. timer
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
"OCC" will be flashing.
Allow control to time-out or press
"Menu", and
control will be in
Occupied override. The normal
program will resume at the start of
the next Occupied event
Override indicators (Control must be showing a fixed display)
Fixed display 1, 2, 3 or 4 must be showing
S
OCC
OVR
SMWTFT
S
UNOCC
OVR
SMWTFT
S
OVR
SMWTFT
F
S
TEMP
OVR
SMWTFT
Setpoint
Actual
Supply
Target
Supply
"UNOCC" will be flashing.
Allow control to time-out or press
"Menu", and
control will be in
Unoccupied override. The normal
program will resume at the start of
the next Unoccupied event
Or – push "Override" again and:
Or – push "Override" again and:
Press or to program
permanent override temperature ,
allow control to time-out or press
"Menu", and the control operates
at the override temperature
regardless of schedule
programming until override
button is pressed again
Auto
1 2 3 4 5 6 7 8
Off
123456789
Stpnt
Reset
?
?
F
S
TEMP ROOM
OVR
SMWTFT
Or
push "Override"
again and: Override
function is shut off.
The control
times-out to starting
fixed display
Note: After selecting an override function,
the user can avoid waiting for the time-out
by pressing the "Menu" button. The control
will return to the starting fixed display
"OCC" indicator on and "OVR"
indicator slowly flashing.
The control is in temporary
occupied override.
Regular
program will resume at the start
of the next occupied event
Setpoint
Actual
Supply
Target
Supply
F
S
TEMP
OCC
SMWTFT
OVR
Setpoint
Actual
Supply
Target
Supply
F
S
TEMP
SMWTFT
OVR
"UNOCC" indicator on and "OVR"
indicator slowly flashing.
The control is in temporary
unoccupied override.
Regular
program will resume at the start
of the next Unoccupied event
"OVR" indicator on steady.
The control is in permanent
override
and the temperature will
be controlled at the permanent
override setting
To cancel an override option that has been selected, press the
"Override" button when the control is showing a fixed display
Setpoint
Actual
Supply
Target
Supply
F
S
TEMP
SMWTFT
OVR
UNOCC
Which mode
is selected?
(See page 3)
Menu Item Override
Menu Item Override
Menu Item Override
Menu Item Override
Menu Item Override
OCCUPIED/UNOCCUPIED OVERRIDE
PROGRAMMING
PROGRAM MENU – "P 0" PROGRAMMING
When "2" and "OCC" are
flashing press or to
select occupied #2 time
PRGM
S SMWTFT
Note: All "PROGRAM" displays are "Time-out" displays
Must be set to
"Int. timer"
Auto
1 2 3 4 5 6 7 8
Perm.
Demand
Ext. timer
Int. timer
Off
123456789
External
Demand
Off
123456
Stpnt
Reset
PRGM
S SMWTFT
Advance through the Menu to the "PROGRAM" display
Only "P 0" can be programmed by the user.
Pre-programmed schedules are located by
pressing "Item" to display "P 1 to P 6". Refer to
"PROGRAM MENU – VIEWING" pg 16
The control will
automatically cycle
to access program-
ming for the next day
When "1" and "UNOCC" are
flashing press or to
select unoccupied #1 time
PRGM
S SMWTFT
PRGM
S
AM
UNOCC
SMWTFT
1
When "1" and "OCC" are
flashing press or to
select occupied #1 time
PRGM
S
AM
OCC
SMWTFT
1
PRGM
S
PM
OCC
SMWTFT
2
When "2" and "UNOCC" are
flashing press or to
select unoccupied #2 time
PRGM
S
PM
UNOCC
SMWTFT
2
The word "SEL" will appear
briefly, "P 0" is selected
PRGM
S SMWTFT
To program schedule
"P 0", press and
at the same time and
hold for one second
When "day" is flashing
press or to select
desired day of week
Options
Every day can be programmed to have
the same schedule
PRGM
S SMWTFT
Press or until all of the
days indicators appear.
Program once for all days
Program "P 0" can be cleared for
re-programming
PRGM
S SMWTFT
Menu Item Override
Press "Item", and At the same
time and hold for one second
A schedule event can be skipped by
programming a "Null Event"
To program a Null Event, Set the time
for that event to between 11:50 PM
and 12:00 AM by pressing or
Wait 20 seconds to time-out to "ACTUAL
SUPPLY" fixed display or Press "Menu" to
advance to viewing "BOILER HOURS OF
USE" and other menu selections. When "P
0" is selected, the "P_0" underscore
indicator will be flashing
Menu Item Override
Menu Item Override
Menu Item Override
Menu Item Override Menu Item Override
Menu Item Override
PRGM
S
OCC
SMWTFT
2

PRE-PROGRAMMED SCHEDULES
18
PROGRAMMING
Schedule "P 1"
Day Time Temperature
Sunday 8:00 am Occ 1
10:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Monday 6:00 am Occ 1
10:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Tuesday 6:00 am Occ 1
10:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Wednesday 6:00 am Occ 1
10:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Thursday 6:00 am Occ 1
10:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Friday 6:00 am Occ 1
10:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Saturday 8:00 am Occ 1
11:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Schedule "P 2"
Day Time Temperature
Sunday 9:00 am Occ 1
9:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Monday 7:00 am Occ 1
9:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Tuesday 7:00 am Occ 1
9:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Wednesday 7:00 am Occ 1
9:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Thursday 7:00 am Occ 1
9:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Friday 7:00 am Occ 1
10:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Saturday 9:00 am Occ 1
10:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Schedule "P 3"
Day Time Temperature
Sunday 8:00 am Occ 1
10:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Monday 6:00 am Occ 1
8:30 am UnOcc 1
5:00 pm Occ 2
10:30 pm UnOcc 2
Tuesday 6:00 am Occ 1
8:30 am UnOcc 1
5:00 pm Occ 2
10:30 pm UnOcc 2
Wednesday 6:00 am Occ 1
8:30 am UnOcc 1
5:00 pm Occ 2
10:30 pm UnOcc 2
Thursday 6:00 am Occ 1
8:30 am UnOcc 1
5:00 pm Occ 2
10:30 pm UnOcc 2
Friday 6:00 am Occ 1
8:30 am UnOcc 1
5:00 pm Occ 2
11:30 pm UnOcc 2
Saturday 8:00 am Occ 1
11:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Schedule "P 5"
Day Time Temperature
Sunday
Null Occ 1
Null UnOcc 1
Null Occ 2
Null UnOcc 2
Monday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Tuesday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Wednesday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Thursday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Friday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Saturday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Schedule "P 6"
Day Time Temperature
Sunday
Null Occ 1
Null UnOcc 1
Null Occ 2
Null UnOcc 2
Monday 1:00 am Occ 1
Null UnOcc 1
Null Occ 2
Null UnOcc 2
Tuesday Null Occ 1
Null UnOcc 1
Null Occ 2
Null UnOcc 2
Wednesday Null Occ 1
Null UnOcc 1
Null Occ 2
Null UnOcc 2
Thursday Null Occ 1
Null UnOcc 1
Null Occ 2
Null UnOcc 2
Friday Null Occ 1
2:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Saturday Null Occ 1
Null UnOcc 1
Null Occ 2
Null UnOcc 2
Schedule "P 4"
Day Time Temperature
Sunday
Null Occ 1
Null UnOcc 1
Null Occ 2
Null UnOcc 2
Monday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Tuesday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Wednesday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Thursday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Friday 7:00 am Occ 1
5:30 pm UnOcc 1
Null Occ 2
Null UnOcc 2
Saturday Null Occ 1
Null UnOcc 1
Null Occ 2
Null UnOcc 2

Technical Specifications
Dimension (h x w x d) — 6-5/8" x 7-9/16" x 2-13/16" (170 x 193 x 72mm)
Weight — 2.9 lbs (1.3 Kg)
Ambient — 30 to 120°F (0 to 50°C), < 95% RH non-condensing
Power supply — 24Vac ±10%, 60Hz, 5VA class II
— For alternate power supplies (50Hz or 24Vdc), contact the factory
Relay capacity — 9 x SPST, 24Vac, 10 Amps – 1 x SPDT, 24Vac, 8 Amps
Sensors — Outdoor Sensor 070, Sensor 071; Accurate with up to 500 feet (150m) 18AWG cable
Control accuracy (temp.) — ±1°F (±0.5°C)
Control Processing — PID algorithm
This electronic control does not exceed the Class B limits for radio noise emissions from digital apparatus as set out in the Radio Interference Regulations of the
Canadian Department of Communications. Le présent numérique n'émete pas de bruits radioeléctriques dépassant les limites applicables aux appareils numériques de
Classe B prescrites dans le réglement sur le brouillace radioeléctrique édicté par le Ministére des Communications du Canada.
Features
18 Indicator lights — Power, Heat Demand, Setpoint, WWSD, Minimum, Comb. air, Pump, Actual Supply, Target Supply
Stage 1, Stage 2, Stage 3, Stage 4, Stage 5, Stage 6, Stage 7, Stage 8, Test
Comb. air damper output — Isolated SPST relay contacts close before first boiler is fired (60 sec.)
Pump output — Isolated SPST relay contacts close when heating or setpoint is required
Stage 1 to 7 output — Isolated SPST relay contacts close to operate each stage
Stage 8 — Isolated SPDT relay contacts. N.O. contacts close to operate Stage 8
Test button — Initiates and controls pre-programmed test run
Error message display — Sensor faults are indicated by flashing light code
Setback timer/clock — Programmable
Memory backup — Retains programmed information and boiler run times when powered down for up to 10 years
Battery backup — Maintains clock operation for 24hrs when powered down
Dial & Switch Settings
Heating Curve — 0.4 to 3.6
Minimum — Off, 80 to 170°F (Off, 27 to 77°C)
Boiler Differential — 2 to 42°F (1 to 23°C)
Stage 1 to 8 switches — To switch each Stage off or into operating mode
Rotate switch — To allow boilers to rotate firing sequence based on hours of use (re-ranks after 48 hrs of use)
Fixed lead switch — Configures Stage 1 to be first/on first/off regardless of hours of use
Fixed last switch — Configures last Stage to be last on first off regardless of hours of use
Lo/Hi fire switch — Configures Stages to fire and rotate as pairs
Timer switch — Setback input from internal timer or external source
Heat Demand switch — External 24Vac signal or permanent internal signal
Setpoint/Reset switch — Control operates in reset or setpoint mode
Keypad Programming
Occupied room temperature — 35 to 105°F (2 to 41°C)
UnOccupied room temperature — 35 to 105°F (2 to 41°C)
Occupied Setpoint temperature — 70 to 248°F (21 to 120°C)
UnOccupied Setpoint temperature — 70 to 248°F (21 to 120°C)
Override temperature — Setpoint or Room temperature ranges depending on mode
Setback schedules — 6 pre-programmed, 1 programmable — 7 day, 2 events per day
Display Readouts
Desired Occ.temperature — 35 to 105°F (2 to 41°C)
Desired UnOcc. temperature — 35 to 105°F (2 to 41°C)
Desired Occ. Setpoint temp. — 70 to 248°F (21 to 120°C)
Desired UnOcc. Setpoint temp. — 70 to 248°F (21 to 120°C)
Override temperature — Setpoint or Room temperature ranges depending on mode
Actual Supply temperature — -67 to 293°F (-55 to 145°C)
Outdoor temperature — -67 to 293°F (-55 to 145°C)
Target supply temperature — 35 to 248°F (2 to 120°C)
Boiler accumulated running times — 0 to 999,999 hrs. for each stage
Setback schedules — 6 pre-programmed, 1 programmable — 7 day, 2 events per day
Time of Day/Day of Week — 12 hr., 7 day clock
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Technical Data

The Right Control For Your Application
THE BOILER CONTROL SPECIALIST
Four Stage Boiler Control 254
Power
Heat
Demand
WWSD
UnOcc.
Minimum
Stage 1
Occupied
35
(2) 105 (41)
70°F
(21°C)
Unoccupied
35
(2) 105 (41)
70°F
(21°C)
Stage 2
Pump
DHW
Demand
Stage 3 Stage 4
Eight Stage Boiler Control 258
Power
Heat
Demand
Minimum
WWSD
Pump
Stage 1 Stage 2
Comb. air
Stage 3
Stage 6
Stage 5
Stage 8
Stage 7
Stage 4
Menu Item Override
Setpoint
Actual
Supply
Target
Supply
S
PRGM
TEMP
FC
TIME
USE
AMPM
UNOCC
OVR
MTWTFS
OUTSIDE
ROOM
1
2
Four Stage Boiler
Control 254 Eight Stage Boiler
Control 258
And more to come!
Contact your wholesaler or
tekmar agent for information
on the newest additions
to the tekmar product line.
Sign up for a tekmar Control
Course or School and stay
up-to-date with our latest
control developments.
Limited Warranty and Product Return Procedure
Two Stage Boiler & DHW
Control 252
Two Stage Boiler & DHW Control 252
Power
Heat
Demand
WWSD
UnOcc.
Minimum
Stage 1
Occupied
35
(2) 105 (41)
70°F
(21°C)
Unoccupied
35
(2) 105 (41)
70°F
(21°C)
Stage 2
System
Pump
DHW
Demand
DHW
Pump
One Stage Boiler & DHW Control 251
Occupied
35
(2) 105 (41)
70°F
(21°C)
Unoccupied
35
(2) 105 (41)
70°F
(21°C)
Power
Heat Demand
DHW Demand
WWSD
Unoccupied
Min. Supply
Boiler
One Stage Boiler & DHW
Control 251
UnOcc
Power
Minimum
One Stage Boiler
Control 250
Boiler On
WWSD
One Stage Boiler
Control 250
Limited Warranty: tekmar warrants to the original purchaser each tekmar product against defects
in workmanship and materials when the product is installed and used in compliance with tekmar's
instructions. Thislimitedwarrantycoversthecostof parts and labour provided by tekmar to correct
defects in materials and/or workmanship. Returned products that are fully operational are not
considered a warranty case. tekmar also does not cover parts or labour to remove, transport or
reinstall a defective product. tekmar will not be liable for any damage other than repair or
replacementofthedefective part orpartsandsuch repair orreplacementshallbe deemed tobethe
sole remedy from tekmar. This warranty shall not apply to any defects caused or repairs required
asaresultofunreasonableornegligentuse,neglect,accident,improperinstallation,orunauthorised
repairoralterations. Incaseof defect, malfunction orfailuretoconformtowarranty, tekmar will, for
a warranty period of 24 months from the date of invoice to the original purchaser or 12 months from
the date of installation of the product, whichever occurs first, repair, exchange or give credit for the
defective product. Any express or implied warranty which the purchaser may have, including
merchantabilityandfitnessforaparticularpurpose,shallnotextendbeyond24monthsfromthedate
of invoice or 12 months from the date of installation of the product, whichever occurs first.
Replacements:tekmarcansendreplacementproductsifrequested. Allreplacementsareinvoiced.
Any possible credit for the replacement will only be issued once the replaced product has been
returned to tekmar.
Product Return Procedure: Products that are believed to have failed must be returned to tekmar
ControlSystemsLtd.4611-23rdStreet,VernonB.C.CanadaV1T4K7whenagreedtoby tekmar. The
installer or other qualified service person must, at the owner's expense, determine which component
has failed. The product must be returned complete with all of its components (sensors, base, etc.).
Productsmustbereturnedtogetherwiththeproofofpurchasetotheoriginalpurchaserwhothenreturns
the product to tekmar after receiving a Return Goods Authorisation (RGA) number from tekmar.
Pleaseinclude thefollowinginformationwiththe product: Thefulladdressoftheoriginalpurchaser,
the RGA number and a description of the problem.
FromtheU.S.A., inorderto avoidcustomscharges,products mustbereturned viaUSPost withthe
package clearly marked with the RGA number, product type and the statement "Canadian Product
returned for repair". For shipping purposes the product can be valued at one half list price.
1) If returned during the warranty period and the product is defective, tekmar will issue full credit
for the returned product less cost of missing parts.
2) Ifreturnedduringthewarrantyperiodandtheproductisfullyoperational,tekmarwill returnthe
product to the original purchaser for a testing cost of $30.00 plus postage.
3) If returned during the warranty period and the product is not damaged and is fully operational,
tekmar can take back the product for a return charge of 40% of the product's net value. This
request has to be specified otherwise the product will be returned with a testing cost of $30.00
plus postage.
4) Ifreturnedafter the warrantyperiodandthe productneedsrepair,tekmar will repairandreturn
the product. Repair and postage costs will be invoiced. tekmar's repair costs are calculated
at $30.00 / hour plus the cost of parts. If the repair costs will be more than $60.00 a repair
estimate will be sent to the original purchaser.
In North America: tekmar Control Systems Ltd ., Canada
tekmar Control Systems, Inc., USA
Head office: 5100 Silver Star Road
Vernon, B.C. Canada V1B 3K4
Tel. [phone] Fax. [phone]
All specifications are subject to change without notice.
Printed in Canada on recycled paper.
Product design, software and literature are Copyright © 1993 by:
tekmar Control Systems Ltd. and tekmar Control Systems, Inc.
Printed in Canada on recycled paper by
Wayside Press Ltd. Vernon / Kelowna, B.C.
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