Tekmar D540 User manual

tekmarNet®4 Thermostat 540
Installation & Operation Manual
D540
08/10
Replaces:03/09
1 of 24 © 2010 D540 - 08/10
Zoning
The tekmarNet®4 Thermostat 540
provides operation for:
One Stage Heat
One Stage Cool
One Stage Fan
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Introduction Features
Requires 7 wires (tN4, C, R, W,
Rc, Y, G)
Outdoor temperature display
Bright backlight
2 button temperature adjustment
Communication with other
tekmarNet®devices improves
system efficiency and comfort
Schedule member status enables
setback operation
Optimum start
Responds to tekmarNet®Scenes
Cooling Group Master
Freeze protection
Exercising
Zone synchronization
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Benefits
Energy savings
Reduced temperature swings
Compatible with tekmarNet®
Timers, User Switches and
Gateway for additional control
Interlock prevents simultaneous
heating & cooling
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Congratulations on the purchase of your new tekmar thermostat.
This manual will step through the complete installation, programming and sequence
of operation for this control. At the back, there are tips for control and system
troubleshooting.
Getting Started
Preparation
tekmar or jeweller screwdriver
Phillips head screwdriver
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Wire Stripper•
Tools Required
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Materials Required
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2, #6 x 1” Wood Screws
18 AWG LVT Solid Wire
(Low Voltage Connections)
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Optional Adapter Plate 007 (for
installation on 2” x 4” gang box)
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Installation
Table of Contents
Getting Started..............................2
Installation .........................................2
Preparation....................................2
Removing The Thermostat Base...3
Mounting The Thermostat Base....3
Thermostat Wiring.........................4
Testing the Thermostat Wiring ......5
Mounting the Thermostat ..............6
Cleaning the Thermostat...............6
Switch Settings..................................7
User Interface....................................8
Display...........................................8
Symbols Description .....................8
Button Operation...........................9
Settings ..................................10-15
Sequence of Operation....................16
Heating Operation.......................16
Cooling Operation .......................17
Fan Operation .............................18
Schedules ...................................19
Scenes (System Override) ..........19
Troubleshooting ...............................20
Error Messages .................... 20-21
Frequently Asked Questions .......22
Job Record..................................23
Technical Data.............................23
Limited Warranty and Product
Return Procedure........................24
Caution
Improper installation and operation of this control could result in damage to the
equipment and possibly even personal injury or death. It is your responsibility
to ensure that this control is safely installed according to all applicable codes and
standards. This electronic control is not intended for use as a primary limit control.
Other controls that are intended and certified as safety limits must be placed into
the control circuit.

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Choose the placement of the thermostats early in the construction process to
enable proper wiring during rough-in.
Consider the following:
Interior Wall.
Keep dry. Avoid potential leakage onto the control.
Relative Humidity max 92% up to 104°F (40°C), 50% RH above 104°F (40°C).
Non-condensing environment.
No exposure to extreme temperatures beyond 36-122°F (2-50°C).
No draft, direct sun, or other cause for inaccurate temperature readings.
Away from equipment, appliances, or other sources of electrical interference.
Easy access for wiring, viewing, and adjusting the display screen.
Approximately 5 feet (1.5 m) off the finished floor.
The maximum length of wire is 500 feet (150 m).
Strip wire to 3/8” (10 mm) for all terminal connections.
Use standard 8 conductor, 18 AWG wire.
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Installation Location
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Removing The Thermostat Base
Push
tab
1Remove thermostat
from base
2
To remove the thermostat base:
Place a small slot screwdriver or similar
tool into the slot located on the top of
the thermostat.
While pushing down against the plastic
tab, pull the thermostat away from the
thermostat’s base.
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Mounting The Thermostat Base
Stud
Switch
Box
Thermostat
Base
007 Adaptor
Plate
31/4”
(83 mm)
If a single gang switch box is used,
an Adaptor Plate 007 is required to
mount the thermostat to the box.
Fasten the base of the
thermostat to the adaptor plate.
Feed the wiring through the
openings in the back of the
adaptor plate and thermostat.
Use the upper and lower screw
holes to fasten the adaptor plate
to the box.
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Mounted on switch box

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If a switch box was not used, mount the
thermostat directly to the wall.
Feed the wiring through the openings in
the back of the thermostat.
Use screws in the screw holes to fasten the
thermostat to the wall. At least one of the
screws should enter a wall stud or similar
rigid material.
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Stud
23/8”
(60 mm)
screwhole
23/8”
(60 mm)
screwhole
Thermostat
Base
Wall
Mounted on wallboard
Thermostat Wiring
The thermostat operates a single heating system zone together with a cooling
system and fan.
Connect tN4, C, R, and W terminals on the thermostat to the tN4, C, R and W terminals
on the tN4 Wiring Center or Zone Manager.
Connect the Rc, Y and G terminals on the thermostat to the R, Y and G terminals
on the cooling equipment.
12 34
tN4 Wiring Center
or
tN4 Zone Mana
g
er
Cooling Equipment
1 Stage
Cooling
1 Stage
Fan
G Y R
D
X
Fan
Cooling
tN4 C W
R
1234
tNt 540
540
One Stage Heat /
One Stage Cool / One Fan
Made in
Canada
Mmm YYYY Lot # 12345
Meets Class B: Canadian ICES FCC Part 15
Power: 24 V ±10% 50/60 Hz 1.8 VA
56 VA fully loaded
Relays: 24 V (ac) 2 A
1001-01
tN4
1C 2R 3W 4
7
G
6
Y
5
Rc
Switch Settings:
For instructions see brochure
Use at least 75°C conductors
Setback
Scene
None
Lock
ON
Unlock
Cool Master 1
Off
Off

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Testing the Thermostat Wiring
Testing the Power
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---------------------------------------------------
1. Remove the front cover from the thermostat.
2. Use an electrical test meter to measure (ac) voltage between the R and C
terminals. The reading should be 24 V (ac) +/– 10%.
3. Install the front cover.
Testing the Heat, Cool, and Fan Relays
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--------------------------------
1. Remove the front cover from the thermostat.
2. Press Mode button until Mode is set to OFF.
3. Set the electrical test meter to continuity.
4. Place probes between R (3) and W (4), then between Rc (5) and Y (6). In both
cases there should be no continuity. If there is continuity then there may be a
wiring fault or the relay may be faulty.
5. Press Mode button until Mode is set to HEAT.
6. Press the button and set the heating temperature above the current room
temperature. Make sure the display does not show “WWSD”. The “H1” symbol
should appear on the display.
7. There should be continuity between the R (3) and W (4) terminals.
8. Press Mode button until Mode is set to COOL.
9. Press the button and set the cooling temperature below the current room
temperature. The “C1” symbol should appear on the display.
10. There should be continuity between the Rc (5) and Y (6) terminals.
11. Press Fan button to set the fan to Auto.
12. Ensure the fan symbol is not shown on the display.
13. There should be no continuity between Rc (5) and G (7) terminals.
14. Press Fan button to set the fan to On.
15. The “Fan” symbol should appear on the display.
16. There should be continuity between the Rc (5) and G (7) terminals.

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Mounting the Thermostat
To place the thermostat back on the
mounting base:
Place thermostat bottom tabs on
matching mounting base notches.
Pivot top of the thermostat
towards wall, ensuring wires clear
obstructions.
The top clasp makes a clicking
sound when properly closed.
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Pivot
Tab
The thermostats’s exterior can be cleaned using a damp cloth. Moisten the cloth
with water and wring out prior to wiping the control. Do not use solvents or cleaning
solutions.
Cleaning the Thermostat
Testing the tekmarNet®4 Bus
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The symbol is shown on the display when communication is present. If the
thermostat is connected in a network and the communication is missing, there may
be an open or short circuit on the tN4 and C bus wires.
1. Remove the front cover from the thermostat.
2. To test for short circuits:
Disconnect the tN4 bus wires on one end.
Install wire nuts on each wire to ensure the wire ends are not touching.
Disconnect the tN4 bus wires on the other end.
Measure for continuity using an electrical meter.
If continuity is present, there is a short circuit fault along the wires. It is
recommended to replace the tN4 bus wires.
3. To test for open circuits:
Disconnect the tN4 bus wires on one end and connect them together.
Disconnect the tN4 bus wires on the other end.
Use an electrical meter to measure for continuity.
If there is no continuity, there is an open circuit fault along the wires. It is
recommended to replace the tN4 bus wires.
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Switch Settings
Switches are set to “On”
position from the factory, and
do not require changing for
most applications.
12 34
1234
tNt 540
540
One Stage Heat /
One Stage Cool / One Fan
Made in
Canada
Mmm YYYY Lot # 12345
Meets Class B: Canadian ICES FCC Part 15
Power: 24 V ±10% 50/60 Hz 1.8 VA
56 VA fully loaded
Relays: 24 V (ac) 2 A
1001-01
tN4
1C 2R 3W 4
7
G
6
Y
5
Rc
Switch Settings:
For instructions see brochure
Use at least 75°C conductors
Setback
Scene
None
Lock
ON
Unlock
Cool Master 1
Off
Off
12 34
1234
Mm
Meets Class B:
Switch Settings:
Setback
Scene
None
Unlock
ON
Lock
Cool Master 1
Off
Off
Switch Position Action
1
ON
SETBACK
The thermostat follows a programmable setback schedule
as a schedule member if available. Requires the installation
of a Timer 033 to use this feature.
OFF OFF
The thermostat does not follow a programmable setback
schedule.
2
ON
SCENE
The thermostat responds to changes in the scene (system
wide manual overrides). Requires the installation of a User
Switch 479 to use this feature.
OFF OFF
The thermostat does not respond to scenes.
3
ON NONE
The thermostat is not part of a cooling group.
OFF COOL MASTER 1
The thermostat is a master of cooling group number 1.
4
ON LOCK ACCESS LEVEL
Locked to ‘User’ access level. Set to Lock when installation
completed.
OFF
UNLOCK ACCESS LEVEL
Unlock to allow ‘User’ and “Installer’ access level. Set to
Unlock during installation process.
tekmarNet®reset control must also be set to Unlocked
(Installer access level).

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SECONDARY DISPLAYMAIN DISPLAY
HEAT
Heat is turned on.
COOL
Cooling is turned on.
FAN
Fan is turned on.
SUN
Operating at the occupied
(day) temperature.
MOON
Operating at the unoccupied
(night) temperature.
COOL GROUP MASTER
Thermostat operates the
cooling for a group of
thermostats.
CLOCK
Operating on a
programmable schedule.
LOCK
Locked to ‘User’ access level.
AWAY
Operating at the Away scene
temperature.
tekmarNet®
Communication is present.
WARNING SYMBOL
Indicates an error is present.
WARM WEATHER SHUT
DOWN
The heating system has been
shut off for the summer.
Display
Symbols Description
Switch between
Heat, Cool, Auto
and Off modes
Switch between
Auto, On and %
Fan operation
Adjust the current temperature
or displayed setting up or down
User Interface

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Button Operation
The Mode button selects between Auto, Cool, Heat, and Off.
Heat Mode: The heating system operates to maintain the Set
Room Heat temperature.
Cool Mode: The cooling system operates to maintain the Set Room
Cool temperature.
Auto Mode: The heating system operates to maintain the Set Room Heat temperature.
Likewise the cooling system operates to maintain the Set Room Cool temperature.
The thermostat will prevent the Set Room Heat and the Set Room Cool settings
from getting closer than 3°F (1.5°C).
To switch from heating to cooling, the heat must be off for at least a 30 minute
interlock period and the actual Room temperature must be at least 3°F (1.5°C)
above the Set Room Heat temperature.
To switch from cooling to heating, the cooling must be off for at least a 30 minute
interlock period and the Room temperature must be at least 3°F (1.5°C) below
the Set Room Cool temperature. Cooling has priority over heating.
Off Mode: The heating and cooling are shut off except heating for freeze
protection.
Mode
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Fan
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The fan button manually turns the fan on or off.
Auto: Fan is usually off but can operate with heating or cooling.
On: Fan is on all the time.
10 to 90%: Fan operates a minimum of this percentage each hour.
Press the or the button to select the room temperature. The display indicates
whether the “HEAT” or the “COOL” temperature is being changed.
Use the or
button to adjust
temperature.
If in Auto mode, press the Mode
button to toggle between Heat or
Cool temperature adjustment.
Room or Temperature
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Settings (1 of 6)
Display Range Access Description Set to
40 to 95°F
(4.5 to 35.0°C)
Default = 70°F
(21.0°C)
Installer User
SET ROOM HEAT Set the room heating temperature while in the event.
40 to 95°F
(4.5 to 35.0°C)
Default = 65°F
(18.5°C)
Installer User
SET ROOM HEAT Set the room heating temperature while in the event.
40 to 95°F
(4.5 to 35.0°C)
Default = 62°F
(16.5°C)
Installer SET ROOM HEAT AWAY
Set the room heating temperature while in the Away scene.
Continued on next page.
• Press and hold down both the and buttons for 2 seconds to change from one step to the next. • Release both buttons once the step has been reached. • Press the or the button to change the setting, if available. • Press and hold down both the and buttons for 2 seconds to go to the next step, OR • After 10 seconds of no button activity, the display goes back to normal operation. • Note: Set switch setting #4 and tekmarNet®system control to Unlock to change Access level to Installer.
Press
+
Together

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Settings (2 of 6)
Display Range Access Description Set to
50 to 100°F
(10.0 to 38.0°C)
Default = 78°F
(25.5°C)
Installer User
SET ROOM COOL Set the room cooling temperature while in the event.
50 to 100°F
(10.0 to 38.0°C)
Default = 85°F
(29.5°C)
Installer User
SET ROOM COOL Set the room cooling temperature while in the event.
50 to 100°F
(10 to 38.0°C)
Default = 85°F
(29.5°C)
Installer SET ROOM COOL AWAY
Set the room cooling temperature while in the Away scene.
Off, 30 sec, On,
On +
Default = 30 sec
Installer User
BACKLIGHT Select the backlight operation. Off = Permanently Off 30 = Temporary on for 30 seconds On = Permanently On On + = On during and off during
Continued on next page.

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Display Range Access Description Set to
°F or °C
Default = °F
Installer User
TEMPERATURE UNITS Press the or the button to change from °F to °C and vice versa.
Device Type with
Software Version,
Address
Installer User
DEVICE TYPE Display alternates between the Device Type (large number) with Software Version (upper right corner) and the thermostat address.
40 to 95°F
(4.5 to 35.0°C)
Default = 85°F
(29.5°C)
Installer MAXIMUM SET ROOM HEAT
Set the maximum room heating limit while in the event.
40 to 95°F
(4.5 to 35.0°C)
Default = 85°F
(29.5°C)
Installer MAXIMUM SET ROOM HEAT
Set the maximum room heating limit while in the event.
40 to 95°F
(4.5 to 35.0°C)
Default = 45°F
(7.0°C)
Installer MINIMUM SET ROOM HEAT
Set the minimum room heating limit.
Settings (3 of 6)
Continued on next page.

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Display Range Access Description Set to
50 to 100°F
(10 to 38.0°C)
Default = 60°F
(15.5°C)
Installer MINIMUM SET ROOM COOL
Set the minimum room cooling limit.
50 to 100°F
(10.0 to 38.0°C)
Default = 95°F
(35.0°C)
Installer MAXIMUM SET ROOM COOL
Set the maximum room cool limit.
OFF, On
Default = OFF Installer
VENTILATION Select whether or not ventilation is required. Setting to on allows the fan to be operated in 10% increments every hour to circulate air in the building.
0, 1, 2, 3
Default = 1 Installer
FAN MODE Select how the fan should operate together with heating and cooling. 0 = Manual operation only 1 = Operate fan with cooling only 2 = Operate fan with heating and cooling 3 = Operate fan with heating only
Settings (4 of 6)
Continued on next page.

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Display Range Access Description Set to
Auto, 10 to 90%,
On
Default = Auto
Installer User
FAN Set the minimum percentage the fan should operate while in the event. This provides ventilation for the building. Each 10% is 6 minutes per hour. Available when: • Ventilation is set to On.
Auto, 10 to 90%,
On
Default = Auto
Installer User
FAN Set the minimum percentage the fan should operate while in the event. This provides ventilation for the building. Each 10% is 6 minutes per hour. Available when:
Ventilation is set to On.•
1, 2, 3, 4
Default = 1 Installer
SCHEDULE Thermostat can follow schedule master 1, 2, 3, or 4. Available when:
Switch setting 1 is set to Setback (On Position).•
Hyd (Hydronic)
or Oth (Other)
Default =
Hydronic
Installer
HEATING TERMINAL TYPE Select if the heating for this zone is hydronic or non- hydronic (other). Available when:
A reset control is present on the tekmarNet® system.
•
Settings (5 of 6)
Continued on next page.

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Display Range Access Description Set to
Auto,
SYn(Synchronize)
Default =
Synchronize
Installer
HEAT CYCLES PER HOUR Select either Auto cycle or Synchronize with other thermostats on the tekmarNet®system. Choose Synchronize when zone heated using a boiler. Choose Auto when zone is non-hydronic heating. Available when:
No reset control on the tekmarNet®system.•
OFF, dLy (delay),
On
Default = On Installer
HEATING SUPPLY PUMP Select whether or not the system supply pump should turn on, be delayed (for thermal motor or wax actuator) or be off to allow a zone group pump per manifold. Available when:
A reset control is present on the tekmarNet®system AND Heating terminal type is set to Hydronic.
•
01 to 24
(no reset control),
b:01 to b:24
(reset control - boiler),
1:01 to 1:24
(reset control - mixing)
Installer
tekmarNet®ADDRESS The address is shown in the large number field. “Auto” is shown in the upper number field when using automatic addressing. Press the or the button to manually select an address. The address can be returned to automatic “Auto” addressing when address set above 24.
None Installer
User
ESCAPE Press the or the button to return to normal operation.
Settings (6 of 6)

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Heating Operation Section A
Sequence of Operation
The thermostat operates the heating system to maintain the Set Room Heat
temperature. The H1 symbol is shown on the display when the thermostat is
heating. The heat can cycle on and off within +/- 1.5°F (1°C) of the Set Room
Heat temperature.
Freeze Protection
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The thermostat operates the heat whenever the room temperature falls below 40°F
(4.5°C), regardless of the thermostat mode.
Heat Terminal Unit
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When the thermostat is connected to a tekmarNet®reset control, the heat source
can be either hydronic or non-hydronic.
When the Heat Terminal is set to Hydronic, the thermostat uses indoor temperature
feedback to fine tune the water temperature and also synchronizes the start of a
heating cycle so that all thermostats start heating at the same time. This reduces
cycling on the boiler.
When the Heat Terminal is set to Other, the thermostat does not use indoor
temperature feedback. This allows the thermostat to operate non-hydronic heating
systems (example: furnace, electric baseboard, or electric fan coil), while remaining
connected to the tekmarNet®system.
Exercising
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When connected to a tekmarNet®reset control, and the heating terminal unit is set
to hydronic, the thermostat exercises the heat relay for 10 seconds every 3 days.
Exercising helps prevent zone valves or zone pumps from failing due to precipitate
buildup. During exercising, the thermostat shows “TEST” on the display.
Flushing
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The flushing feature is for open-loop systems that use a domestic hot water tank
as a heat source. Flushing ensures that fresh potable water is circulated through
the system once each day. If the thermostat is connected to a tekmarNet®reset
control with the Flushing feature turned on, the thermostat display will display the
“FLUSH” icon for the duration of the flushing operation.
Hydronic System Supply Pump
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When connected to a tekmarNet
®
reset control, the thermostat’s Supply Pump
setting affects how the primary pump or mix pump on the reset control operates.
When connected to the boiler bus, the primary pump is affected. When connected
to the mix bus, the mix system pump is affected.
If the thermostat operates a motorized zone valve or a zone pump, the Supply
Pump setting should be set to On.

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Cooling Operation Section B
The thermostat operates the cooling system to maintain the Set Room Cool
temperature. The C1 symbol is shown on the display when the thermostat is
cooling. The cooling can cycle on and off within +/- 1.5°F (1°C) of the Set Room
Cool temperature.
The cooling system has a fixed minimum on time of 2 minutes and a minimum off
time of 5 minutes in order to prevent cooling equipment short cycling.
Cooling Groups
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In order to prevent heating and cooling at the same time, this thermostat can operate
together with other thermostats on a tekmarNet®system to form a cool group. When
this thermostat is set as the Cool Group 1 master, it operates the cooling equipment
for the group. Other thermostats can be set to become members of cool group
1. When the cooling is turned on, all cool group member thermostats ensure the
heating is off. This thermostat is the master of Cool Group 1 when switch setting
3 is set to “Cool Master 1” (down position). When operating as a cool group, the
air temperature readings of all the cool group member thermostats are displayed
on the master as an average.
The cool group average temperature is shown as the “Room” temperature while
the mode is set to Cool, or the mode is set to Auto and the thermostat is allowing
cooling operation. In all other modes, the
cool group master thermostat measures
and displays the built-in “local” temperature
sensor measurement.
Fluctuations in the displayed “Room”
temperature may occur during automatic
mode switch over when the display changes
from using the local temperature for heating
to using the cool group average temperature
for cooling.
Cool Group 1
Master MemberMember
tN2 Communication
If the thermostat operates a thermal motor (wax actuator) zone valve, set the Supply
Pump setting to Delay. This provides a three minute delay to allow the zone valve to
open before the primary or mix pump is turned on and the boiler is allowed to fire.
In special applications with multiple zoning manifolds, the Supply Pump setting
can be set to Off. This allows a Zone Group Pump located on the Zone Manager,
or Wiring Center to operate the pump for the manifold.
DHW Tank Priority
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---------------------------------------------------
When a tekmarNet®reset control is heating an indirect Domestic Hot Water (DHW)
tank, the thermostat may shut off the heating zones to allow the DHW tank to recover
quickly. This is determined by the DHW priority of the tekmarNet®reset control.
Warm Weather Shut Down
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When the outdoor air temperature exceeds the Warm Weather Shut Down (WWSD)
setting on the tekmarNet®reset control, the heating system is shut off.

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The fan relay includes a post purge feature. After the heating is shut off, the fan
continues to operate for 30 seconds. After the cooling is shut off, the fan continues
to operate for 10 seconds.
The user can also select to operate the fan manually by pressing the Fan button.
This allows the user to choose between Auto and On. “Auto” allows the fan to
operate together with heating or cooling but normally the fan is off. “On” forces the
fan to operate continuously.
The fan button is inactive when the Fan Mode is 0 and Ventilation is set to Off.
Ventilation Fan
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In order to provide ventilation to the building, the fan can also operate for additional
time beyond what is required for the heating and cooling systems. Ventilation allows
the user to select the fan to operate for a minimum percentage out of each hour.
Options are 10 to 90%, in 10% (6 minutes per hour) increments, as well as Auto and
On. This is available when the Ventilation setting in the Adjust menu is set to On.
Once Ventilation is set to On, the Fan minimum run time percentage during the
and events can be set so that the fan can operate on a schedule and/or together
with scenes.
Fan Operation Section C
Fan Mode The fan operates with...
0 Not With Heating Nor Cooling (Only with fan button)
1 Cooling Only
2 Heating and Cooling
3 Heating Only
The thermostat normally operates the fan together with the heating and cooling
systems. This is determined by the Fan Mode setting in the Adjust menu.

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Schedules Section D
Lowering the room temperature setting reduces the amount of fuel required to heat
the building resulting in energy savings. Likewise, raising the cooling temperature
results in energy savings.
This thermostat can follow a programmable schedule in order to automatically lower
the room temperature setting. A schedule master such as a Timer 033 is required
in order to gain programmable schedule functionality.
When operating on a programmable schedule, a symbol is shown, as well as a
or a . The or indicates the current operating temperature.
If a symbol does not appear, there is no schedule available.
Display Action
Occupied temperature. No schedule.
Unoccupied temperature. No schedule.
Programmable schedule at occupied temperature.
Programmable schedule at unoccupied temperature.
Scene Display Room Temperature Setting
1or or Follows programmable schedule or
operates at the occupied temperature.
2Away Away temperature.
3Unoccupied temperature.
Scenes (System Override) Section E
When a programmable schedule is selected, there is a time delay for the temperature
to change from the temperature to the temperature.
The thermostat uses Optimum Start to predict the heat up and cool off rate of
the room. The optimum start feature allows the room to reach the set room
temperature by the time set in the programmable schedule. This applies for both
heating and cooling.
Scenes provide an easy way to save energy while away on vacation, or override a
pre-set schedule when plans change. tekmarNet®devices such as a User Switch
479 provide scene adjustment.
This thermostat responds to the following scenes:
While in the Away scene, the room temperature cannot be changed using the or
buttons. Change the scene from Away to or to change the temperature.

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Troubleshooting
Error Messages (1 of 2)
Error Message Description
CONTROL ERROR The thermostat was unable to correctly read settings from memory and has reloaded the factory default settings. The thermostat does not operate the heating, cooling, or the fan while this error message is present. Error clears once all adjust menu settings in the Installer access level (unlocked) have been checked. Set thermostat’s switch setting #4 to unlock and unlock the tekmarNet®system control. Then press and hold and buttons together for 2 seconds to enter the adjust menu. Continue until all settings have been reveiwed. BUS ERROR The tekmarNet®4 communication bus has either an open or a short circuit. The result is that there are no communications. Check for loose wires. Check for short circuits between the tN4 and C wires on the House Control, Wiring Center, or Zone Manager. Check for correct polarity between the C and R wires. Error clears automatically once wiring fault has been corrected. If the thermostat is intentionally removed from the tekmarNet®4 bus, press the and buttons
together to clear the error message.
DEVICE LIMIT The number of devices on the tekmarNet
®
bus has exceeded 24. Devices include tekmarNet
®
Thermostats and Setpoint Controls. The device count must be lowered to 24 or less. If possible, move devices to other tekmarNet®buses. Error clears automatically once the number of devices on the tekmarNet®bus is at 24 or lower.