Super Hot SG-135-E Manual

PN2362763
SG SERIES BOILERS
INSTALLATION AND SERVICE MANUAL
SG SERIES BOILERS
INSTALLATION AND SERVICE MANUAL
Models SG-135-E to SG-270-E
FOR MODELS SG-135-E TO SG-495-E
SEE REAR COVER FOR INDEX
Manufactured by
Allied Engineering Company
Division of E-Z-Rect Manufacturing Ltd.
Manufacturers of Gas and Electric Boilers, Stainless Steel Tanks, Heat Exchangers and Electric Boosters.
94 Riverside Drive, North Vancouver, B.C. V7H 2M6 •Telephone [phone] •www.alliedboilers.com
Branches: Calgary •Edmonton •Toronto •Denver
Improper installation, adjustment, alteration, service or maintenance can cause property
damage, injury, or loss of life.Please carefully read this manual. For assistance o
r
additional information, consult a qualified installer, service agency or the gas supplier.
WARNING
FOR MODELS SG-135-E TO SG-495-E
SEE REAR COVER FOR INDEX
Manufactured by
Allied Engineering Company
Division of E-Z-Rect Manufacturing Ltd.
Manufacturers of Gas and Electric Boilers, Stainless Steel Tanks, Heat Exchangers and Electric Boosters.
94 Riverside Drive, North Vancouver, B.C. V7H 2M6 •Telephone [phone] •www.alliedboilers.com
Branches: Calgary •Edmonton •Toronto •Denver

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SG SERIES BOILERS
DIMENSIONS AND SPECIFICATIONS
FOR MODELS SG-135 TO SG-270
Standard Model Includes:
•Electronic Ignition
•Zone Control Board with Transformer
•Stainless Steel Burners
•Combination Gas Valve
•High Limit Sensor
•Temperature / Pressure Gauge
•A.S.M.E. Pressure Relief Valve
•Drain Valve
•Draft Hood
•Blocked Vent Safety Switch
•Flame Roll-out Safety Switch
•Automatic Vent Damper
“PS” Packaged Models Include
Standard Model Parts plus:
•Circulating Pump
•Custom Cast Iron Pump Adapter
•Expansion Tank
•Air Purger
•Combination Fill / Regulator Valve
•Automatic Air Vent
Options:
•Natural Gas add suffix "N" - Propane models add suffix “P”
•Electric Ignition add suffix “E”
•High/Low fire add suffix “M” - Consult Factory for Availability
•Add 45 pounds weight (20 kg) for packaged boilers - add suffix “PS”
INPUT* OUTPUT** DIM A DIM B DIM C DIM D DIM E GAS
CONN. F
SHIPPING
WEIGHT
MODEL
NUMBER MBH kW MBH kW in cm in cm in cm in cm in cm NPT lb kg
SG135 135 39.6 114 33.4 14.7 37.3 9.5 24.1 6.0 15.2 45.3 115 4.5 13.9 0.50” 191 87
SG180 180 52.8 152 44.5 17.7 45.0 9.5 24.1 6.0 15.2 45.3 115 4.5 13.9 0.50” 222 101
SG225 225 65.9 190 55.6 20.7 52.6 9.5 24.1 7.0 17.8 46.5 118 6.5 16.5 0.75” 253 115
SG270 270 79.1 228 66.9 23.7 60.2 9.5 24.1 8.0 20.3 47.6 121 7.5 19.0 0.75” 284 129
Allow 24” (609 mm) minimum in front for servicing.
Minimum clearances to combustible material: Top 24” (610 mm), Sides 2" (51 mm), Rear 2" (51 mm), Flue 6" (153 mm)
APPROVED FOR COMBUSTIBLE FLOORS & CLOSET INSTALLATION.
The Super Hot product improvement program may result in changes to the design and / or specifications being made without notice.
* For altitudes above 2,000 feet, refer to Section 3.6 to determine the appropriate Input derate or contact the factory.
** Output based on Natural Gas models

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SG SERIES BOILERS
DIMENSIONS AND SPECIFICATIONS
FOR MODELS SG-315 TO SG-495
Standard Model Includes:
•Electronic Ignition
•Stainless Steel Burners
•Gas Valve
•Redundant Gas Valve
•Operating Aquastat
•High Limit Sensor
•Temperature / Pressure Gauge
•A.S.M.E. Pressure Relief Valve 30 p.s.i.
•Drain Valve
•Draft Hood
•Transformer
•Control Panel Enclosure
* In Canada: For altitudes above 2,000 feet, contact the factory for the appropriate Input derate.
* In U.S.A.: For altitudes above 2,000 feet, reduce input 4% for each 1000 feet above sea level.
** Add 3” to dimension ‘A’ (1 1/2” to each side of boiler) to allow for 2” NPT water connections.
Options:
•Natural Gas add suffix "N" - Propane models add suffix “P”
•Electric Ignition add suffix “E”
•High/Low fire add suffix “M” - Full Modulation add suffix “MOD”
INPUT* OUTPUT DIM A** DIM B DIM C DIM D GAS
CONN. F
SHIPPING
WEIGHT
MODEL
NUMBER MBH kW MBH kW H.P. in Cm in cm in cm in cm
Typical
NPT lb kg
SG315 315 92.3 265 77.7 7.9 26.7 67.8 9.5 24.1 8.0 20.3 47.6 121 3/4” 307 140
SG360 360 106 303 88.8 9.0 29.7 75.4 9.5 24.1 9.0 22.9 48.6 124 3/4” 336 153
SG400 400 117 337 98.7 10.0 32.7 83.1 9.5 24.1 9.0 22.9 48.6 124 3/4” 368 167
SG450 450 132 379 111 11.3 35.7 90.7 15.5 39.4 10.0 25.4 55.3 140 1” 395 180
SG495 495 145 416 122 12.4 38.7 98.3 15.5 39.4 10.0 25.4 55.3 140 1” 424 193
Allow 24” (610 mm) minimum in front for servicing.
Minimum clearances to combustible material: Top 24” (610 mm), Sides 2” (51 mm), Rear 2” (51 mm), Flue 6" (153 mm)
APPROVED FOR COMBUSTIBLE FLOORS & CLOSET INSTALLATION, do not install on carpeting.
The Super Hot product improvement program may result in changes to the design and / or specifications being made without notice.

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Boiler Water Flow Data
NOTE: The boiler should be properly sized for its heating application and maintain an adequate water
flow rate during operation. Significantly oversizing the boiler or decreasing boiler water flow
rate will cause excessive stage cycling and may result in premature failure of components.
Typical Water Flow Versus Pressure Drop Across Boiler
20°F T.D. 30°F T.D.
Model
Number U.S. GPM P.D. FT. U.S. GPM P.D. FT.
SG135 11.4 2.8 7.6 1.2
SG180 15.1 2.8 10.1 1.2
SG225 18.9 2.8 12.6 1.2
SG270 22.7 2.8 15.1 1.2
SG315 26.5 3.2 17.7 1.3
SG360 30.3 3.2 20.2 1.4
SG400 33.6 3.3 22.4 1.4
SG450 37.8 3.8 25.2 1.6
SG495 41.6 4.0 27.7 1.8

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5
ABOUT OUR MANUALS
Your Super Hot boiler has been provided with two manuals:
•User's Information Manual - This manual is intended for the owner or user of the boiler and provides
information on routine operation and maintenance, and emergency shutdown.
•Installation and Service Manual - This manual must only be used by a qualified heating installer,
service technician or gas supplier. Installation or service by anyone unqualified to do so may
result in severe personal injury, death or substantial property damage.
Both manuals should be kept in the envelope provided and affixed adjacent to the boiler so that they are
readily available for future reference.
Lighting Instructions Section 1
1.1 SAFETY INSTRUCTIONS
WARNING
If you do not follow these instructions exactly, a fire or explosion may result causing property
damage, personal injury or loss of life.
A. BEFORE LIGHTING smell all around the
boiler area for gas. Be sure to smell next to
the floor because some gas is heavier than
air and will settle on the floor.
WHAT TO DO IF YOU SMELL GAS
•Do not try to light any appliance.
•Do not touch any electrical switch; do not
use any phone in your building.
•Immediately call your gas supplier from a
neighbor's phone. Follow the gas
supplier's instructions.
•If you cannot reach your gas supplier,
call the fire department.
B. Use only your hand to push in or turn the gas
control knob. Never use tools. If the knob will
not push in or turn by hand, don't try to repair
it, call a qualified service technician. Force or
attempted repair may result in a fire or
explosion.
C. Do not use this boiler if any part has been
under water. Immediately call a qualified
service technician to inspect the appliance
and to replace any part of the control system
and any gas control which has been under
water.
1.2 LIGHTING INSTRUCTIONS
Determine the ignition system that applies from the list below and go to the applicable lighting instruction
section.
•Intermittent electronic ignition with combination gas valve (Section 1.3)
•Intermittent electronic ignition with non-combination gas valve (Section 1.4)
Note: A combination gas valve combines the operating and safety shut-off into one valve body. A non-
combination gas valve system utilizes separate valve bodies for operating and safety shut-off.
If you are unsure which type of gas valve or ignition system your boiler is equipped with, check the
lighting instructions sticker on the boiler or contact the factory.

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1.3 LIGHTING INSTRUCTIONS FOR INTERMITTENT ELECTRONIC IGNITION
WITH COMBINATION GAS VALVE.
1. This boiler is equipped with an ignition device
which automatically lights the pilot. Do not try
to light the pilot by hand. Ensure gas supply
to the boiler is turned on.
2. STOP! Read the safety instructions in
Section 1.1.
3. Set the room thermostat to lowest setting.
4. Turn off all electrical power to the appliance.
5. Remove control access panel if necessary.
6. Push in gas control knob slightly and turn
clockwise to "OFF".
NOTE: On some gas valves the knob cannot
be turned to "OFF" or “ON” position unless
knob is pushed in slightly. Do not force.
7. Wait five (5) minutes to clear out any gas.
Then smell for gas, including near the floor. If
you smell gas, STOP! Follow "A" in the safety
instructions in Section 1.1. If you don't smell
gas, go to the next step.
8. Turn gas control knob counterclockwise
 to "ON".
9. Replace control access panel if necessary.
10. Turn on all electrical power to the boiler.
11. Set room thermostat to desired setting.
12. If the appliance will not operate, follow the
instructions "To Turn Off Gas To Boiler" in
Section 1.6 and call your service technician or
gas supplier.
To turn off gas to boiler or emergency shut-off
Follow Section 1.5.
1.4 LIGHTING INSTRUCTIONS FOR INTERMITTENT ELECTRONIC IGNITION
WITH NON-COMBINATION GAS VALVE.
This boiler is equipped with an ignition device, which automatically lights the pilot. Do not try to light the
pilot by hand. Before turning on the electrical power switch, be sure all gas supply lines are purged of air
and power supply to control is the correct voltage.
If the pilot or main burners are not lit or the control system is locked-out due to flame failure, close the
main and pilot gas shut-off valves and call your service technician or gas supplier. If you smell gas,
STOP! Follow “A” in the safety instructions in Section 1.1.
Check Control Operation
1. STOP! Read the safety instructions in
Section 1.1.
2. For 100% shut off check, close main and pilot
manual gas shut off valves, turn off all
electric power to the boiler and wait for five
minutes to clear out any gas.
3. Then smell for gas, including near the floor.
If you smell gas, STOP! Follow safety
instructions in Section 1.1. If you don’t smell
gas, go to the next step.
4. Set the thermostat above room temperature
and turn on all electric power to the boiler to
energize the electronic ignition and pilot
valve. After a few seconds, control system
should “lockout” and all functions are off.
5. To take the control system out of “lockout”
either press the reset button or interrupt
power to the boiler, depending on the boiler
controller. Some controllers will retry ignition
automatically after 5 minutes lockout.
Start System
1. Turn on the main and pilot manual gas shut-
off valves.
2. Set thermostat above room temperature and
turn on all electrical power to the boiler.
3. Once the pilot flame is proven, the controller
opens the main burner gas valves. The pilot
flame will ignite the gas as it exits the main
burner ports.
4. Set thermostat to the desired setting to put
system back in service.
Relight Operation
Five minutes complete shut off period is required
before attempting to relight the boiler. To relight
the boiler, follow the Start System procedure
(above).
To turn off gas to boiler or emergency shut-
off
Follow Section 1.5

SG Series Boilers – Installation and Service Manual
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Text Description Display
STA Status (see status
numbers)
StA
BT Boiler temperature bt
SP Operating setpoint SP
HL High limit setpoint HL
HDF Differential set-point HdF
FLA Flame current FLA
RUN Run time hours run
CYC Boiler cycles CYC
ERR Error (see error numbers) Err
Table 1 Run Mode Parameters
1.5 TO TURN OFF GAS TO THE BOILER OR EMERGENCY SHUT-OFF
WARNING
Should boiler overheat, or the gas supply fail to shut off, do not turn off or disconnect the
electrical supply to the circulating pump. Instead, shut off the gas supply at a location external
to the boiler.
1. Set the thermostat to the lowest setting.
2. Turn all electrical power to the boiler off.
3. Remove control access panel on the boiler if necessary.
4. For combination valve: Push in gas control knob slightly and turn clockwise to "OFF". Do not
force it.
For non-combination valve: Close the main and pilot manual gas shut off valves. The valve is "OFF"
when handle is perpendicular to the direction of gas flow.
5. Replace control access panel if necessary.
1.6 CONTROLLER PROGRAMMING AND SERVICE CODES
2012 NRCan and DOE Compliance and Operation
Operation of this control may delay the burner operation while the residual heat is circulated
out of boiler.
The integrated boiler control module provides ignition
sequence, flame monitoring and safety shutoff for intermittent
pilot spark ignition. It also provides limit rated water
temperature control for with two separate sensors in one
casing (3-wire).
The control is located on the front panel inside the boiler.
The control display, along with Up ▲, Down ▼, and “I” keys
may be used to view boiler operating status and program
parameters (Figure 1).
1.6.1 RUN MODE Fi
g
ure 1 Control Dis
p
la
y
In the RUN mode, status items and parameters are
viewable.
To read settings, press and release the “I” key to find the
parameter of interest. Each setting will alternately flash
between the relevant display code listed in the Table 1
and its corresponding value. For example, press and
release “I” key until “HL_” setpoint is displayed, it will then
flash a three-digit number, i.e., 220, followed by ˚F (or ˚C).
This indicates that the boiler water temperature of 220 ˚F
is set. Other operating parameters display the settings in
a similar fashion.

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1.6.2 INSTALLER MODE
To enter the adjustment mode:
1. Press with Up ▲, Down ▼, and “I” keys (see Figure 1) simultaneously for three seconds.
2. Press and release the “I” key until the parameter (listed in the Table 2) requiring adjustment is
displayed.
3. Press with Up ▲or Down ▼key until the parameter has reached the desired value.
4. After 60 seconds without any key inputs, the control will automatically return to the RUN Mode.
Table 2 Installer Mode O
p
tions
3-Digit 7-Segment Display
1st Screen 2nd Screen (setting value) 3rd Screen
Default Range Description
HL_ <high limit> ˚F or ˚C 180 ˚F 130 to 220 ˚F Adjust high limit setting
HdF <high limit differential> ˚F or ˚C 15 ˚F 10 to 30 ˚F Adjust high limit
differential
Or_ <pump overrun time> Sec 60 sec 0 to 120 seconds Pump post-purge time
otH <ODR maximal temp.> ˚F or ˚C 55 ˚F 40 to 70 ˚F Maximal outdoor
temperature
otL <ODR minimal temp.> ˚F or ˚C 0 ˚F -40 to 40 ˚F Minimal outdoor
temperature
btL <minimal water temp.> ˚F or ˚C 140 ˚F 130 to 150 ˚F Minimal boiler
temperature
tPL <minimal boiler temp.> ˚F or ˚C 140 ˚F OFF,
120 to 160 ˚F
Thermal purging
minimal temperature
(parameter is available
only if outdoor
temperature is invalid)
tPt <maximal delay> Min 2 1 to 10 minutes
Maximal thermal purge
time (parameter is
available only if outdoor
temperature is invalid)
rSt On or OFF N/A N/A Reset lockout
F-C ˚F or ˚C ˚F ˚F or ˚C Select degrees ˚F or ˚C
mode

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1.6.3 OPERATING CHECKOUT
After adjusting parameters, put the boiler into operation and observe operation through at least one
complete cycle to make sure that the controller operates properly. See controller troubleshooting section
to assist in determining boiler operation.
The sensor should fit snugly and should touch the bottom of the well for best temperature response. The
sensor is held inside the well using the well clip.
1.6.4 THERMAL PURGE
The intent of thermal purge is to ensure usable residual heat in the boiler is circulated until it is sufficiently
depleted from the system before the burner is allowed to fire. To that end, on a call for heat, the burner
remains off while the circulator runs until the boiler temperature drops to the thermal purge temperature
limit or the time delay is exceeded. Both of these parameters are adjustable. When the boiler temperature
falls below the thermal purge temperature limit or the time delay expires, the burner is allowed to fire.
In addition to the thermal purge temperature and thermal purge time delay parameters, two other
conditions release the integrated boiler controller from thermal purge and allow the burner to run in order
to maintain comfort in the space:
•The boiler temperature has dropped 10 °F from the boiler water temperature measured at the
beginning of the call for heat.
•Boiler temperature is cooling at a rate greater than 5 °F/minute while the circulator is running.
1.6.5 OPERATING STATE CODES AND TROUBLESHOOTING
When there is a problem during a call for heat or boiler operation, the controller provides specific
information to help resolve the issue quickly. If the controller is displaying “StA” by a number, use the
state code definitions in the Table 3 to determine the problem and possible causes.
1.6.6 CONTROLLER MOUNTING
The controller has four tabs which align with four slots in the control panel. To remove the controller,
press and hold in the bottom two tabs while simultaneously rotating the controller about 45 degrees to
unhook the top two tabs.
Rotate 45°
PRESS and HOLD
both tabs while
rotating controller

SG Series Boilers – Installation and Service Manual
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Display
Code
State Specific Description
Operation Sequence
Idle/Standby The boiler is in standby - no call for heat
StA ↔1 Run circulator Heat request present but boiler water temperature sufficiently high to
run circulator pump only (no ignition sequence)
Thermostat Calls For Heat
Self Test Hardware self check, check of connected periphery, it is performed
at start up, in the beginning of the heat cycle and in the “Wait For
recovery” state
StA ↔17
Wait for recovery There is an external error and the control is waiting to recover, no
lockout
Circulator output energizes
StA ↔ 2
Wait for end switch
to open
The control is waiting for the end switch of the vent damper to open
at the beginning of a heat cycle. If the end switch doesn’t open in 60
seconds, the control goes to error code Err 2
StA ↔ 3
Wait for end switch
to close
The control is waiting for the end switch of venting damper to close at
the beginning of a cycle. If the end switch doesn’t close within 60
seconds, the control goes to error code Err 29
StA ↔ 4 Pump pre-purge/
thermal purge
System is purging before ignition trial-safety relay diagnostics
followed safety relay switch-on during last 2 seconds this sate
StA ↔ 6 Spark, ignition
activation
System is sparking permanently 13 seconds whilst pilot gas valve
relay is turned on
StA ↔7Prove flame System is proving flame signal, typically 2 seconds
StA ↔8Running System is in running mode, flame signal must be present
Call For Heat Ends
StA ↔9Pump post-purge System is purging at the end of a call for heat
Troubleshooting/Diagnostics
StA ↔10 Inter-purge
(retry/recycle delay)
If the control loses flame signal during state code 7 or 8, or flame is
not detected during stat code 6 to 8, it will recycle through the 30
seconds purge time and last 2 seconds part of pre-purge time
Err ↔ 2
Wait for end switch
to open – failed
closed
The end switch of venting damper has not opened at the beginning
of the heat cycle. The control is not in lockout
Err ↔ 29
Wait for end switch
to close – failed
open
Waiting time for pressure switch to close expired. The control is not
in lockout
Err ↔ 62 Soft lockout System is shutdown and will re-start following an enforced delay
StA ↔15 Wait for limit to close There may be a call for heat from the thermostat, but the limit switch
is open
Flame out of
sequence – before
trial
Flame signal sensed before trial for ignition.
Flame out of
sequence – after
trial
Flame out of sequence during post-purge.
StA ↔16
Wait for flame loss Flame signal still present when not expected.

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If the controller is displaying “Err” followed by a number, use the error code definitions in the Table 4 to
determine the problem and possible causes.
Table 4 Error Codes
Display State Solution
Err ↔ 2 End switch of venting
damper failed to open
The end switch contacts stuck closed. Check the venting
damper and replace it if necessary.
Err ↔ 4 Low flame current Check pilot assembly and replace it if necessary.
Err ↔ 6 Flame sensed out of
normal sequence
Flame sensed out of normal sequence (before opening gas
valve or after closing gas valve).
Err ↔18 Gas valve relays
welded 5 consecutive
soft lockouts
A manual reset is required.
Err ↔ 23 Flame sensed during
pre-purge
Flame sensed during pre-purge (before gas valve signaled
opened)
Err ↔ 24 Flame sensed during
post-purge
Flame sensed during post-purge (before gas valve signaled
closed)
Err ↔ 29 End switch of venting
damper failed to close
The end switch contacts stuck open. Check the venting
damper and replace it if necessary.
Err ↔ 32 Sensor error
Temperature sensor or interface failure (open or short
connection, increased connection resistance, dual sensor
mismatch) or failure of A/D conversion (invalid offset or gain,
too many failures during A/D conversion).
Err ↔ 57 Flame rod shorted to
burner ground Check and adjust or replace if necessary.
Err ↔ 58 AC line frequency error AC signal is too noisy or frequency is incorrect.
Err ↔ 59 Line voltage error AC voltage out of specification high or low.
Err ↔ 60 Thermostat input
higher than threshold Check thermostat wiring and replace it if necessary.
Err ↔ 61 Line voltage unstable Possibly too many heavy loads switching on and off cause
erratic supply voltage.
Err ↔ 62 Soft lockout Maximum number of retries exceeded.
Err ↔ 63 Soft lockout Maximum number of recycles exceeded.
Err ↔ 64 Soft lockout
Internal failure (Electronics failure). Caused by general
electronics failure such as relay open or shorted contacts,
flame sensing circuit error, or A to D error.
Err ↔ 65 Over temperature error Sensor measured temperature in excess of ECO limit.

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12
1.7 BC-1 CONTROLLER (FOR 2 STAGE BOILERS ONLY)
WARNING
For boilers equipped with the BC-1 Controller, read all instructions in this manual and the BC-1
Controller Manual before placing the boiler in operation or making adjustments to the
controller. Adjustments must be made by a qualified heating technician.
The BC-1 controller is supplied as standard option with two stage boilers for models SG-315 and larger.
It is not supplied with boilers equipped with a full modulating gas valve. For convenience, the BC-1
controller is factory wired to terminal block TB4 and ready for field wiring connections. The field wiring to
TB4 is determined based on the operating mode selected (i.e. mode 1 to 6), the heating application and
the piping arrangement (i.e. parallel or primary/secondary). Refer to Figure 2 for the wiring diagram
according to each mode. For important instructions regarding programming and operation of the BC-1
controller, refer to the BC-1 Controller Manual included with your boiler.
Power Outputs from BC-1:
Boiler Stage outputs from 15-STG1 and 17-STG2
terminals from the BC-1 are 24 Vac, 60 Hz (when
factory wired).
Figure 2 – BC-1 Controller
Alarm output from 23-ALARM terminal from the BC-1 is
24 Vac, 60 Hz, 0.45 A maximum (when factory wired).
Alarm is wired to terminal block TB4, terminals AL&AL.
Signal Inputs (Do not apply external power):
The following signal inputs are located on terminal block TB4:
HT&R: Room thermostat or zone valve end switch,
24Vac switching input, closed is activation.
ST&R: Setpoint DHW aquastat, 24Vac switching
input, closed is activation.
FS&FS: Flow switch, 24Vac switching input, closed
is activation.
Thermistor Sensors
BO&CM: Boiler outlet sensor
BI&CM: Boiler inlet sensor
OS&CM: Outdoor sensor
SD&CM: Supply / DHW sensor
BC-1 Controller Mounting
The BC-1 controller mounts on separate bracket on the control panel using a sheet metal screw at the top
center. To remove the controller: 1.) remove the front casing panel, 2.) pull off the black top cover of the
controller, 3.) unscrew the sheet metal screw, 4.) lift the controller slightly out of the rectangular cutout in
the mounting bracket, 5.) pull off the Molex connector while simultaneously holding down the tab on the
left side.

SG Series Boilers – Installation and Service Manual
13
Field wiring to terminal block TB4
Figure 3 – Field wiring to terminal block TB4

SG Series Boilers – Installation and Service Manual
14
Electrical Connections
For all electrical connections: Strip wire ends and insert into the terminal block. Tighten terminal screw
clamps to securely hold the wire.
CAUTION - Risk of damage to the controller - Do not apply power to any connections on terminal
block TB4. 24 Vac has been factory wired to terminals C-1 and HL-15.
Terminal
Block
Connections Name Description / Comments
BO & CM Boiler Outlet
Sensor
Connect boiler outlet water temperature sensor to terminals
BO and CM (common). The Boiler Outlet Sensor must be
attached using a cable tie to the boiler outlet pipe.
BI & CM Boiler Inlet
Sensor
Connect inlet water temperature sensor to terminals BI and
CM (common). The Boiler Inlet Sensor must be attached using
a cable tie to the boiler inlet pipe.
OS & CM Outdoor
Sensor
Optional Outdoor Sensor (for Mode 4 and 5 only): Connect
Outdoor Sensor 070 to terminals OS and CM (common). The
Outdoor Sensor is installed on an exterior wall, typically facing
North, and above the snow line. It should be shielded from
effects of heat or cold to prevent false outdoor temperature
readings. Avoid direct sunlight, exhaust fans, appliance vents,
and excessive moisture.
SD & CM Supply/DHW
Sensor
Optional (for Modes 2, 3, and 5 only). Connect a Supply or
DHW Sensor 071 to terminals SD and CM (common). The
Supply/DHW sensor is inserted into a thermowell on the DHW
tank or attached using a cable tie to the supply pipe.
AL & AL Alarm Optional. The alarm contacts are a powered output, do not
apply power. Connect an alarm (beeper, light, or relay) with a
rating of 24 Vac and maximum 0.45 A to terminals AL and AL.
FS & FS Flow Switch Not used. Leave Jumper 5-6 on TB4. For convenience, the
Flow Switch terminals have been relocated to terminal block
TB2, poles T1 & S. Do not apply power.
ST & R Setpoint DHW
Demand
Optional Domestic Hot Water Aquastat (for Modes 4 and 5
only): Connect domestic hot water aquastat to terminals ST
and R. Closed is activation. Do not apply power.
TB4
HT & R Heat Demand Connect Thermostat or Zone Valve End Switch to terminals
HT and R. Closed is activation. Do not apply power.

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1.7.1 BC-1 CONTROLLER OPERATION
When the controller is powered, the controller enters the operating mode if there are no sensor or high
limit errors present. The user should select one of the following modes from the controller adjust menu:
Mode 1 - Setpoint operation using parallel piping: Operates boiler stages to maintain fixed
temperature at boiler outlet sensor when a heat demand is present.
Mode 2 - Setpoint operation using primary/secondary piping: Operates boiler stages to maintain
fixed temperature at boiler supply sensor when a heat demand is present.
Mode 3 - Dedicated DHW Generation: Operates boiler stages to maintain fixed temperature at the
boiler outlet sensor when an internal demand for DHW is generated based on the DHW sensor. An
indirect hot water tank must be used to isolate the boiler from an open system.
Mode 4 - Outdoor reset with reset override using parallel piping: Operates stages to maintain an
outdoor reset temperature at the boiler outlet sensor. When there is a call for “reset override” from
the DHW aquastat (i.e. ST&R is closed), the control operates the stages to maintain a setpoint
temperature at the boiler outlet sensor. If both heat demand and setpoint DHW demand are present
at the same time, the controller targets the higher of the two requirements.
Mode 5 - Outdoor reset with reset override using primary/secondary piping: Operates stages to
maintain an outdoor reset temperature at the boiler supply sensor. When there is a call for “reset
override” from the DHW aquastat (i.e. ST&R is closed), the control operates the stages to maintain a
setpoint temperature at the boiler supply sensor. If both heat demand and setpoint DHW demand are
present at the same time, the controller targets the higher of the two requirements.
Mode 6 – External boiler control: It is not necessary to use Mode 6 since Direct Digital Control
(DDC) terminals have been provided on terminal block TB1. The DDC terminals may be used for
connecting a boiler or multiple boilers to an external boiler control or an energy management system
(EMS). See boiler wiring diagram for connection details.
When there is a heat demand or DHW demand the controller will switch on the system pump. If the
sensor is not satisfied, the controller will switch stages on, in sequence, based on PID logic (proportional,
integral, derivative). The controller continuously monitors the sensors and examines the difference
between the target temperature and the sensor temperature. Depending on the difference in temperature
(proportional), the time (integral), and how fast or slow the temperature is changing (derivative), it will
determine when to switch a stage on or off. This feature prevents "short cycling", which can quickly wear
out components and cause rapid temperature fluctuations.
The heating routine will operate until the water temperature reaches the user-defined temperature setting.
Once reached, the control will automatically cycle the stage(s) of the boiler on or off, as necessary, to
maintain the supply water temperature. The required number of stages which are activated is determined
by the controller. After the call for heat has been satisfied, the stage(s) of the boiler will switch off, in
sequence, followed by the pump.
1.7.2 RESET OVERRIDE
WARNING
If both Heat Demand and Setpoint DHW Demand are present at the same time, the controller
targets the higher temperature of the two requirements. This may result in higher than intended
water temperatures in either space heating loop or domestic hot water (DHW) heating loop.
Use pipe rated for use at the highest possible water temperature.
The BC-1 Controller has one pump relay which is normally open and will close (i.e. pump energized)
when either a Heat Demand or Setpoint DHW Demand is present. When using Reset Override, a
switching external pump relay (e.g. tekmar Relay 003) should be utilized to stop hot water flow to the
space heating loop (e.g. radiant in-floor) and redirect it to the DHW heating loop during a Setpoint DHW
Demand. See Figure 4 and Figure 5.

SG Series Boilers – Installation and Service Manual
16
Figure 4 – Typical piping diagram in Mode 4
Sequence of Operation
Thermostat (T1) closed - Thermostat creates a Heat Demand resulting in a boiler target based on the
outdoor reset settings. The boiler pump (Pump1) operates.
DHW Aquastat (A1) closed - DHW Aquastat creates Setpoint DHW Demand and activates external
pump relay. The external pump relay causes the following actions:
1) Power for the boiler pump (Pump1) is broken. Pump1 does not operate.
2) Power for the DHW pump (Pump2) is made. Pump2 operates.
3) Setpoint DHW Demand creates a boiler target based on the higher requirement of the
outdoor reset and reset override setting.
2S
1S
1T1T 1A
1Pump
2Pump
MM
MODE 4 ONLY
(Outdoor reset and reset override)
S1 = Boiler Outlet Sensor 071
S2 = Boiler Inlet Sensor 071
Pump1 = Boiler Pump
Pump2 = DHW Pump
A1 = DHW Aquastat
T1 = Thermostat
A1
Pump 1
Pump 2
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Figure 5 – Wiring diagram illustrating use of an External Relay to control pump operation

SG Series Boilers – Installation and Service Manual
17
Installation Instructions Section 2
2.1 RECEIVING
INSPECT SHIPMENT FOR POSSIBLE DAMAGE. All goods are carefully manufactured, inspected,
checked and packed by experienced workers. The manufacturer's responsibility ceases upon delivery of
goods to the carrier in good condition. Any claims for damage, shortage in shipment or non-delivery must
be filed immediately against the carrier by the consignee.
Use care when receiving and unpacking the boiler. Dropping the boiler may cause damage and prevent
safe and proper operation.
2.2 INSTALLATION CODES AND REQUIREMENTS
All applicable national, provincial/state, and local codes, laws, regulations, and ordinances must be
followed. They expand on and take precedence over any recommendations in this booklet. Authorities
having jurisdiction shall be consulted before installations are made.
In Canada, the installation must conform to the requirements of the authority having jurisdiction or, in the
absence of such requirements, to the CAN/CSA B149 Installation Codes (current edition). All electrical
wiring must be in accordance with the Canadian Electrical Code, CSA C22.1 Part 1 (current edition) and
applicable local codes.
In the United States of America, the installation must conform to the requirements of the authority
having jurisdiction or, in the absence of such requirements, to the National Fuel Gas Code, ANSI Z223.1
(current edition). All electrical wiring must be in accordance with the National Electrical Code, ANSI/NFPA
70 (current edition) and applicable local codes.
Where required by the authority having jurisdiction, follow the Standard for Controls and Safety Devices
for Automatically Fired Boilers, ANSI/ASME CSD-1 (current edition).
2.3 LOCATION
SG boilers are intended for indoor installation only. Observe the following minimum clearances from the
boiler to combustible materials:
Minimum Clearances to Combustible Materials
Sides Rear Top Front (service)
Model in. mm in. mm in. mm in. mm
SG 2 51 2 51 24 610 24 610
•Minimum clearance from the boiler front to combustible materials is 6” (153 mm); however, a front
clearance of 24” (609 mm) is recommended for servicing.
•Maintain a clearance of 6" (152 mm) from draft hood and the flue pipe in any direction.
•Allow ample space for boiler inlet and outlet connections, and gas connection.
•Boiler must be installed on a stable and level foundation.
•SG Series boilers can be installed on a combustible floor but must not be installed directly on
carpeting.
•A hot water boiler installed above radiation level must be provided with a low water cutoff
device at the time of boiler installation.
•This boiler must be installed such that gas ignition system components are protected from water
(dripping, spraying, rain, etc.) during appliance operation and service.

SG Series Boilers – Installation and Service Manual
18
2.4 GAS SERVICE PIPING
The boiler and its gas connection must be leak tested before placing the boiler in operation. The gas
controls furnished are suitable for a maximum operating gas pressure of 1/2 psi (14 inches water
column).
The boiler and its individual shutoff valve must be disconnected from the gas supply piping system during
any pressure testing of that system at test pressures in excess of 1/2 psig (14 inches water column).
The boiler must be isolated from the gas supply piping system by closing its individual manual shutoff
valve during any pressure testing at test pressures equal to or less than 1/2 psig (14 inches water column).
A manual main shut-off valve should be installed in the gas line outside the boiler jacket and as required
in Section 2.2. The valve should be readily accessible for turning on and off.
A drip pocket or sediment trap should be installed in the gas supply line upstream of the gas controls and
as close to the boiler as possible (example shown in Figure 8 in Section 5).
Some of the pressure regulators or pressure regulating sections of gas valves are provided with an
integral vent limiter and threaded connection. A bleed or gas relief line should be connected to it and
piped to the outdoors.
The pipe compound used should be resistant to the action of liquefied petroleum gases. Check for gas
leaks in piping before placing the boiler in operation by using a soap and water solution. DO NOT USE
AN OPEN FLAME.
INSTALLER MUST IDENTIFY EMERGENCY SHUT-OFF DEVICES.
All piping and fittings must be installed as per codes in Section 2.2.
2.5 AIR SUPPLY FOR COMBUSTION AND VENTILATION
A sufficient air supply MUST be provided to this boiler. Air openings to the boiler room provide the air for
combustion, flue gas dilution and ventilation and are always required, regardless whether the air is taken
from inside or outside. The air opening size and location (as well as other air supply and venting
considerations) must conform to Section 2.2.
The boiler room must never be under a negative pressure. Always provide air openings sized not only to
the dimensions required for the total input of all fuel-fired appliances in the boiler space, but also to
handle the air movement rate of any exhaust fans or air movers using air from the building or space.
The venting terminations must always be kept clear of obstructions (i.e. snow, ice, etc.). Louvers and
grilles used in the air supply and ventilation system should be kept clear of any dust, dirt, or debris which
will block proper air flow.
2.6 CORROSIVE ATMOSPHERES
If a gas boiler is to be installed near a corrosive or potentially corrosive air supply, the boiler should be
isolated from it and outside air should be supplied as recommended in Section 2.5.
Chemical vapors from products containing chlorine or fluorine must be avoided. Even though these
chemicals may be safe to breathe, corrosive substances can become liberated when passed through a
gas flame. Even at low concentrations, these chemicals can significantly contaminate the air supply and
shorten the life of any gas burning appliance. The following is a list of some of the products which should
be avoided:
•bleaches and chlorinated cleaning products
•paints and sprays
•water softeners (calcium or sodium chloride)
•leaking refrigeration equipment
•freon from common aerosol dispensers

SG Series Boilers – Installation and Service Manual
19
These chemicals are especially commons near swimming pools, beauty shops, dry cleaning
establishments, laundry areas, workshops, and garages. The warranty is void when failure is due to
corrosion.
2.7 VENTING
The responsibility of providing a suitable vent of adequate draft capacity and in good usable condition is
that of the gas fitter/installer. Interference with the air supply for the boiler shall be prohibited.
Vent installation and type of gas vent or vent connector MUST follow all applicable national,
provincial/state, and local codes, laws, regulations, and ordinances as described in Section 2.2.
For boilers for connection to gas vents or chimneys, vent installations shall be in accordance with Part 7,
Venting of Equipment, of the National Fuel Gas Code, ANSI Z223.1 or Section 7, Venting Systems and
Air Supply for Appliances, of the CAN/CGA B149, Installation Codes, or applicable provisions of the local
building codes.
The venting shall be supported as required by applicable code(s). Horizontal runs shall slope upward not
less than ¼ inch per foot (21 mm/m) from the boiler to the vent terminal.
This unit must be installed with the factory supplied draft hood in place. The draft hood is a safety device
designed to control chimney drafts that might affect combustion or blow out the pilot. The draft hood
supplied with the boiler must not be altered. The minimum skirt height as indicated on the draft hood
must be maintained.
Vent connectors serving the boiler must not be connected into any portion of mechanical draft systems
operating under positive pressure.
Vent Terminal Information
The minimum distance from the termination of a vent terminal to adjacent public walkways, adjacent
buildings, openable windows and building openings shall be not less than those values specified in the
National Fuel Gas Code, ANSI Z223.1 and/or CAN/CGA Installation Codes.
For proper operation, the vent terminal must be kept free of snow and other debris at all times.
To prevent discoloration and degradation of building materials by flue gases and flue gas condensation,
ensure that the vent terminal is installed clear of nearby obstacles. In all cases, installation shall be in
accordance with code.
Maintain a minimum clearance of 4 feet (1.22 m) horizontally, and in no case above or below, unless a 4
foot (1.22 m) clearance is maintained from electric meters, gas meters, regulators and relief equipment.
Removal of an Existing Boiler
When an existing boiler is removed from a common venting system, the common venting system is likely
to be too large for proper venting of the appliances connected to it.
At the time of removal of an existing boiler, the following steps shall be followed with each appliance
remaining connected to the common venting system placed in operation, while the other appliances
remaining connected to the common venting system are not in operation.
a) Seal any unused openings in the common venting system.
b) Visually inspect the venting system for proper size and horizontal pitch and determine there is no
blockage or restriction, leakage, corrosion and other deficiencies which could cause an unsafe
condition.
c) Insofar as is practical, close all building doors and windows and all doors between the space in which
the appliances remaining connected to the common venting system are located and other spaces of
the building. Turn on clothes dryers and any appliance not connected to the common venting
system. Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they will
operate at maximum speed. Do not operate a summer exhaust fan. Close fireplace dampers.

SG Series Boilers – Installation and Service Manual
20
d) Place in operation the boiler being inspected. Follow the lighting instructions. Adjust the thermostat
so the boiler will operate continuously.
e) Test for spillage at the draft hood relief opening after 5 minutes of main burner operation. Use the
flame of a match or candle, or smoke from a cigarette, cigar or pipe.
f) After it has been determined that each appliance remaining connected to the common venting system
properly vents when tested as outlined above, return doors, windows, exhaust fans, fireplace
dampers and any other gas burning appliance to their previous conditions of use.
g) Any improper operation of the common venting system should be corrected so the installation
conforms with the National Fuel Gas Code, ANSI Z223.1 and/or CAN/CGA Installation Codes. When
re-sizing any portion of the common venting system, the common venting system should be resized
to approach the minimum size as determined using the appropriate tables in Part 11 of the National
Fuel Gas Code, ANSI Z223.1 and/or CAN/CGA Installation Codes.
2.8 AUTOMATIC VENT DAMPER
All boilers with an input of 300,000 Btu/h and under are supplied with an automatic vent damper. The
following instructions must be observed:
•The automatic vent damper should be installed at the top of the factory supplied draft hood (Figure 1 -
Alternate 3). No modifications to the automatic vent damper are permitted.
•The venting system must be arranged so that only the boiler is served by the automatic vent damper
with which it was supplied.
•Connect the wiring harness from the boiler to the automatic vent damper as indicated on the supplied
wiring drawings.
•The automatic vent damper position indicator should be clearly visible after installation.
•A minimum clearance of not less than 6 inches (153 mm) must be maintained between the automatic
vent damper device and combustible construction. Provision must be made for service access to the
automatic vent damper.
•The automatic vent damper must be in the open position when the boiler's main burner is operating.
•For orientation other than vertical, refer to automatic vent damper installation instructions
2.9 BLOCKED VENT AND FLAME ROLL-OUT SAFETY SWITCHES
All boilers with an input of 300,000 Btu/h and under are equipped with blocked vent and flame roll out
safety switches. The blocked vent safety switch is installed in the clip provided on the draft hood (Figure 6
- Alternate 1) or is mounted with screws (Figure 6 - Alternate 2). The blocked vent safety switch is pre-
wired at the factory either directly to the boiler controls (Figure 6 - Alternate 1 & 2), or through a wiring
harness for a boiler with an automatic vent damper (Figure 6- Alternate 3). If the vent becomes blocked a
boiler shut down will occur. Ensure that the vent is free of obstructions.
The flame roll out safety switch will cause a boiler shutdown if the heat exchanger becomes blocked with
soot or corrosion.
WARNING
Shut down of the boiler by either the “Blocked Vent” or the “Flame Roll-out” safety switch is an
indication that carbon monoxide may be improperly venting into the premises and the boiler
must be serviced by a qualified person who is capable of determining the cause of the shut
down and can take corrective action. Carbon monoxide is a lethal, colorless and odorless gas.