Green Mountain GMHB125 Instruction manual

Manufactured by:
ECR International Inc.
2201 Dwyer Avenue, Utica, NY 13501
Tel. [phone]
www.ecrinternational.com
PN 240012363 REV. B [03/29/2019]
Condensing Wall Mounted
Gas Fired
INSTALLATION, OPERATION &
MAINTENANCE MANUAL
Models
GMHB125
GMHB160
GMCB150
GMCB200

2
Fully Assembled Boiler Metal Wall Bracket w/ 4 ea Wall Screws
and Plugs
Concentric to Two Pipe
Adapter
GMHB125/GMCB150
Shown
Temperature Pressure
Gauge
4 ea - 17x24x2 Gaskets Includes Essential
Documents and Warranty
11x17 Wire Diagrams
5 GPM Flow Restrictor
GMCB200 Combi Only Used for Valve Connections Document Package 30 PSI Safety Relief Valve
Gas Ball Valve Drain Valve Condensate Fitting
VERIFY CONTENTS RECEIVED
PN 240012363 REV. B [03/29/2019]
Not Shown - Literature Package.

3
TABLE OF CONTENTS
1 - Important Safety Information.........................6
2 - Introduction....................................................7
2.1 Installation Requirements .................................... 7
2.2 ANSI/ASME CSD-1. ........................................... 7
2.3 Requirements Massachusetts...................................7
2.4 Use Of A Carbon Monoxide Detector........................ 7
2.5 Designated Use.................................................... 7
2.6 The Unit Must Not:............................................... 7
2.7 Operational Features............................................. 7
3 - Component Listing...........................................8
4 - Locating Boiler..............................................12
4.1 Boiler Location Considerations..............................12
4.2 Service And Combustible Clearances.....................13
4.3 Wall Mounting....................................................14
5 - Hydronic Piping.............................................15
5.1 General ............................................................15
5.2 Special Conditions..............................................16
5.3 Safety Relief Valve And Air Vent...........................17
5.4 Trim Piping........................................................18
5.5 System Piping ...................................................18
................ 20
5.7 Central Heating System......................................24
5.8 Frost Protection Mode.........................................24
5.9 Pump Protection (Automatic Pump Exercise)...... 24
5.10 Domestic Hot Water Mode .................................24
5.11 Manufacturer Recommendation - Filter................26
6 - Combustion Air And Vent Piping....................27
6.1 General ............................................................27
6.2 Removal Of Existing Boiler From Common Vent
System..................................................................27
6.3 Fill Condensate Trap With Water...........................28
 ........................................................28
6.5 Vent Termination ...............................................29
6.6 Approved Venting Materials ................................29
6.7 ApprovedPolypropyleneManufacturers...................30
6.8 Coaxial Venting Instructions................................31
6.9 Coaxial Vent Screw Placement .............................31
6.10 Twin Pipe Systems ...........................................33
6.11 Securing Twin Pipe Polypropylene Venting........ 34
6.12 Flexible Vent System .......................................37
6.13 Condensate Piping............................................39
7 - Gas Supply & Piping......................................40
7.1 General ............................................................40
7.2 Leak Check Gas Piping........................................41
8 - Electrical Connections...................................42
8.1 General ............................................................42
8.2 Electrical Connections.........................................42
8.3 Access To Connection Block.................................43
8.4 Main Supply Connection......................................43
8.5 Install Room Thermostat.....................................44
8.6 Optional Electrical Connections ............................45
8.7 Indirect Storage Tank.........................................47
Wiring Diagrams ............................................ 49-56
9 - Start Up Procedure .................................57
9.1 Central Heating System Connections - Heat Only....57
9.2 Central Heating System Connections - Combi ........57
9.3 Gas Conversion .................................................58
9.4 System Start Up................................................58
9.5 Commission Setup (Electric)................................59
9.6 Control Panel ....................................................59
9.7 Commission Setup (Gas) ....................................60
9.8 De-Aeration Function (See Figure 9-2)..................60
9.9 Commissioning..................................................60
9.10 Combustion Adjustment....................................62
9.11 Chimney Sweep Function/Manual Co2 Adjust........63
9.12 Check Firing Rate.............................................64
9.13 Adjusting Maximum Heating Power................. 64
10 - Operating Instructions................................65
10.1 Boiler Sequence Of Operation ............................65
10.2 Testing For Gas Leaks & Purging The Gas Supply...65
10.3 Boiler Controls.................................................66
10.4 Boiler Operation...............................................78
10.5 Central Heating Mode .......................................78
10.6 Combi Domestic Hot Water Mode .......................78
10.7 Frost Protection ...............................................78
10.8 Pump .............................................................78
10.9 Low Water Pressure Sensor (Internal) ...............78
11 - General Maintenance And Cleaning .............79
11.1 Beginning Of Each Heating Season .....................79
11.2 Maintenance And Routine Servicing.....................80
11.3 Component Replacement And Cleaning................81
11.4 Draining The Boiler...........................................81
11.5 Draining The Heating Circuit..............................81
11.6 Combi (DHW)..................................................82
11.7 Cold Water Filter..............................................82
11.8 Maintenance....................................................82
11.9 Final Assembly ................................................82
11.10 User Information............................................83
11.11 Safety Flue Thermostat...................................83
11.12 Replacement Parts..........................................83
11.13 Gasket Kit.....................................................83
12 - Ratings And Capacities................................84
12.1 Ratings And Capacities......................................84
......................84
13-Troubleshooting............................................86
13.1 Initial Fault Finding Checks................................86
13.2 Error Diagnostics ............................................86
13.3 Error Table for Installer....................................86
13.4 Errors Codes ..................................................87
13.5 Errors In Fault History Only ..............................89
14 - Glossary......................................................90
PN 240012363 REV. B [03/29/2019]

4
Dimensions
PHYSICAL DATA
Central Heating (Sealed System) 125 / 150 160 / 200
Heat Exchanger Max Allowable Working
Pressure 50 psig [3.45 bar] 50 psig [3.45 bar]
Max System Pressure 43.00 psig [2.96 bar] 43.00 psig [2.96 bar]
Min System Pressure 7.25 psig [ 0.50 bar] 7.25 psig [0.50 bar]
Max System temperature 176°F [80°C] 176°F [80°C]
Pressure Relief Valve Setting 30.00 psig [2.11 bar] 30.00 psig [2.11 bar]
Expansion Tank Minimum Size
(pre-charge press.) 2.2 gal at 11.6 psi [10.0 L at 0.8 bar] 2.2 gal at 11.6 psi [10.0 L at 0.8 bar]
Recommended System Pressure (cold) 21.7 psig [1.5 bar] 21.7 psig [1.5 bar]
Domestic Hot Water (Sealed System) 150 200
Max Inlet Water Pressure 116 psig [8 bar] 116 psig [8 bar]
Min Inlet Water Pressure 2.9 psig [ 0.2 bar] 2.9 psig [0.2 bar]
Min DHW Flow Rate 0.55 gpm [2.50 L/min] 0.55 gpm [2.50 L/min]
Max DHW Temperature 140°F [60°C] 140°F [60° C]
DHW Water Content 0.05 gal [0.23 L] 0.10 gal [0.37 L]
SYSTEM
When boiler is operating at maximum operating temperature, providing heating with all heat emitters operating, pressure gauge

PN 240012363 REV. B [03/29/2019]
DIMENSIONS 125 & 150 160 & 200
Height 30" [763 mm] 30 " [763 mm]
Width 17  " [450 mm] 17  " [450 mm]
Depth 14" [356mm] 23" [584 mm]
Condensate Trap Connection
3/4" NPT 3/4" NPT
System Supply 1" NPT 1" NPT
DHW Outlet (GMHB125 Optional) 3/4” NPT 3/4” NPT
Gas Connection 3/4” NPT 3/4” NPT
DHW (Cold Water) Inlet 3/4” NPT 3/4” NPT
System Return 1" NPT 1” NPT
Boiler Filling Connection 1/2" [15.9mm] External to Boiler
Primary Water Content 1 gal [3.60 L] 1 gal [4.73 L]
B
A
C
D
E
F
G
H
I
J

5
PHYSICAL DATA
Vent
Connector
*Combustion
Air
Front View
All Models
160/200
Top View
160 HEAT
0NLY
Bottom View
Dimensions
200 COMBI
Bottom View
Dimensions
150 COMBI
Bottom View
Dimensions

7"
3"


125 HEAT
ONLY
Bottom View
Dimensions

4"
DEIG
C
B
DEIG
C
B
FH


125/150
Top View
Vent
Connector
*Combustion
Air
Wall
Wall
Wall
Wall
Wall
Wall
* For optional 2 pipe venting, otherwise use outside ring
of vent connector. PN 240012363 REV. B [03/29/2019]
D
C
E IHGF
B
A
D E IG
C
5"
B

F J
5" 7"

6"
6"
5"
7"


6" 6"
9"

9"
B

6
1 - IMPORTANT SAFETY INFORMATION
CAUTION
Indicates a hazardous situation which, if not avoided,
could result in minor or moderate injury.
!
WARNING
Indicates a hazardous situation which, if not avoided,
could result in death or serious injury.
!
DANGER
Indicates a hazardous situation which, if not avoided,
WILL result in death or serious injury.
!
This is the safety alert symbol. Symbol alerts you
to potential personal injury hazards. Obey all safety
messages following this symbol to avoid possible
injury or death.
Become familiar with symbols identifying potential hazards.

glossary for additional information.
WARNING
Fire, explosion, asphyxiation and electrical shock
hazard. Improper installation could result in death or
serious injury. Read this manual and understand all
requirements before beginning installation.
!
1. Safety Information
WARNING
Do not tamper with or use this boiler for any purpose
other than its intended use. Failure to follow these
instructions could result in death or serious injury.
Use only manufacturer recommended parts and
accessories.
!
CAUTION
Laceration, burn hazard. Metal edges and parts may
have sharp edges and/or may be hot. Use appropriate
personal protection equipment to include safety
glasses and gloves when installing or servicing this
boiler. Failure to follow these instructions could result
in minor or moderate injury.
!
NOTICE
Used to address practices not related to personal
injury.
DANGER
Fire, explosion, asphyxiation hazard. This boiler is set
operate with Natural Gas. A conversion kit is included
with this boiler for use with Propane. Do not operate
this boiler before identifying the type of fuel to be
used and conversion to propane if necessary. Failure
to follow these instructions WILL result in death or
serious injury.
!
PN 240012363 REV. B [03/29/2019]

7
Information and specications outlined in this manual in eect at the
time of printing of this manual. Manufacturer reserves the right to
discontinue, change specications or system design at any time without
notice and without incurring any obligation, whatsoever.
2 - INTRODUCTION
2.5 Designated Use
• GMCB150 and GMCB200 provide both central heating
and domestic hot water.
• GMHB125 and GMHB160 central heating only.
• Indoor installation.
• Closet or alcove installation. Direct Vent Boiler does not
require air vents when installed in closet or room.
• Direct vent boiler.
• 
(LP/propane).
2.6 The unit MUST NOT:
• Directly heat potable water. Indirect heating is
acceptable.
• Heat water with non-hydronic heating system chemicals
present (example, swimming pool water).
• Toxic chemicals, such as those used for boiler
treatment, shall not be introduced into potable water
used for space heating.
• Exceed 43 psig (2.96 bar) maximum system pressure,
or drop below minimum system pressure 7.25 psig (.50
bar)
• Exceed 176°F (80°C) system design temperature.
• Shall not be installed on carpeting.
2.7 Operational Features
• Modulates to provide CH Turndown 5:1, DHW Turn
down 6:1.
• Maximum output available for domestic hot water:
GMCB150- 133,000 btu/h (39 kW), capable of providing
3.4 (U.S.) gpm (13.2 liters/min) with a temperature rise
of 70°F/39°C.
GMCB200 - 176,000 btu/h (52 kW), capable of
providing 4.9 (U.S.) gpm (18.9 liters/min) with
temperature rise of 70°F/39°C.
• 
• Outdoor Temperature Reset optional.
• Heat exchanger over heat protection.
• Boiler operating at maximum operating temperature,
providing heat, pressure gauge should not indicate
more than 26.11 psig / 1.80 bar. If reading exceeds

• 
pump(s) and relay/zone control board.
2 - Introduction
2.1 Installation shall conform to requirements of
authority having jurisdiction or in absence of such
requirements:
UNITED STATES
• National Fuel Gas Code, ANSI Z223.1/NFPA 54 .
• National Electrical Code, NFPA 70.
2.2 Where required by authority having jurisdiction,
installation shall conform to Standard for Controls
and Safety Devices for Automatically Fired Boilers,
ANSI/ASME CSD-1.

2.3 Requirements for Commonwealth of
Massachusetts:
Boiler installation must conform to Commonwealth of
Massachusetts code 248 CMR which includes but is not limited
to:

2.4 Manufacturer recommends the use of a carbon
monoxide detector for all installations.
2.4.1 A carbon monoxide detector may be required
by local code, follow all local codes.
PN 240012363 REV. B [03/29/2019]

8
3 - COMPONENT LISTING
Illustrations are a depiction of the boiler for general location of parts and may vary depending on model.
2
1
17
10
15
12
11
20
22
5
21
25
23
24
14
7
ITEM
NO. GMHB125
1Pump with Air Separator
2Boiler Drain Tap
3System Return
4a DHW Indirect Tank Return
4b DHW Indirect Tank Supply
5Gas Valve
6DHW Indirect Tank Supply
7
8System Supply
9Condensate Trap
10 3-Way Valve with Motor
11
Water Safety Thermostat
12
NTC Heating sensor (Supply /
Return)
QTY 2, (1 Shown for
clarity)
13 Ignition electrode
14 Spark Generator
15 Flue Sensor
16 Aerator
17 Coaxial Flue Connector
18 Heat Exchanger Temperature
Sensor
19 Heat Exchanger
20 Burner (not shown)
21 Flame Detection Electrode
22 Air/Gas Blend Manifold
23 Acoustic Silencer
24 Fan
25 Venturi
3
13
9 68 4a
18
4b
16
PN 240012363 REV. B [03/29/2019]
GMHB125 Heat Only

9
3 - COMPONENT LISTING
Illustrations are a depiction of the boiler for general location of parts and may vary depending on model.
ITEM
NO. GMHB160
1Pump
2System Return
3
4System Supply
5Gas Valve
6
Condensate Trap
7
NTC Heating sensor (Supply/
Return)
QTY 2, (1 Shown for
clarity)
8Water Safety Thermostat
9Spark Generator
10 Ignition Electrode
11 Flue Sensor
12 Aerator
13 Coaxial Connector
14 Heat Exchanger Temperature
Sensor
15 Heat Exchanger
16 Burner (not shown)
17 Flame Detection Electrode
18 Air/Gas Blend Manifold
19 Acoustic Silencer
20 Air Purge
21 Venturi
22 Fan
2
1
13
11
7
6
14
9
17
5
22
18
20
10
19
15
21
3
4
8
12
PN 240012363 REV. B [03/29/2019]
GMHB160 Heat Only

10
3 - COMPONENT LISTING
Illustrations are a depiction of the boiler for general location of parts and may vary depending on model.
2
1
17
10
15
12
11
19
22
5
21
25
23
24
14
7
ITEM
NO. GMCB150
1Pump with Air Separator
2Boiler Drain Tap
3System Return
4a DHW Indirect Tank supply
4b Flow Sensor with Water Filter
and Flow Restrictor
5Gas Valve
6a DHW (Hot Water) Outlet
6b NTC DHW Sensor
7
8System Supply
9Condensate Trap
10 3-Way Valve with Motor
11
Water Safety Thermostat
12
NTC Heating sensor (Supply/
Return)
QTY 2, (1 Shown for
clarity)
13 Ignition electrode
14 Spark Generator
15 Flue Sensor
16 Aerator
17 Coaxial Flue Connector
18 Heat Exchanger Temperature
Sensor
19 Heat Exchanger
20 Burner (not shown)
21 Flame Detection Electrode
22 Air/Gas Manifold
23 Acoustic Silencer
24 Fan
25 Venturi
3
13
9
6a8 4a
18
4b
6b
16
PN 240012363 REV. B [03/29/2019]
GMCB150 Combi

11
Illustrations are a depiction of the boiler for general location of parts and may vary depending on model.
3 - COMPONENT LISTING
1
17
10
16
12
11
19
22
5
21
25
23
24
14
7
ITEM
NO. GMCB200
1Pump with Air Separator
2System Return
4a DHW (Cold Water ) Inlet
4b Flow Sensor with Water Filter
and Flow Restrictor
5Gas Valve
6a DHW (Hot Water) Outlet
6b NTC DHW Sensor
7
8System Supply
9Condensate Trap
10 3-Way Valve with Motor
11
Water Safety Thermostat
12
NTC Heating sensor (Supply/
Return)
QTY 2, (1 Shown for
clarity)
13 Ignition electrode
14 Spark Generator
15 Aerator
16 Flue Sensor
17 Coaxial Flue Connector
18 Heat Exchanger Temperature
Sensor
19 Heat Exchanger
20 Burner (not shown)
21 Flame Detection Electrode
22 Air/Gas Manifold
23 Acoustic Silencer
24 Air Purge
25 Venturi
26 Fan
2
13
9
6a
84a
18
4b
6b
26
15
PN 240012363 REV. B [03/29/2019]
GMCB200 Combi

12
4 - LOCATING BOILER
4.1 Boiler Location Considerations
Installation shall conform to requirements of
authority having jurisdiction or in absence of
such requirements:
National Fuel Gas Code, ANSI Z223.1/NFPA 54 .
National Electrical Code, NFPA 70.
• Ambient room temperature always above 32°F (0°C) to
prevent freezing of liquid condensate.
• Approved for installation in closets or alcove provided
it is correctly designed for that purpose and minimum
clearances are met.
• Protect gas ignition system components from water
(dripping, spraying, rain, etc.) during operation and
service (circulator replacement, condensate trap,
control replacement, etc.).
• Access to outdoors to meet minimum and maximum
pipe lengths for combustion air and vent piping. See
section 6.
• Disposal of condensate. See section 6.
• Drainage of water (or water - antifreeze solution)
during boiler service or from safety relief valve
discharge. See section 5.
• Access to system water piping, gas supply, and
electrical service. See sections 5, 7 and 8.
• Clearances to combustible materials and service
clearances. See Table 1 and Figures pg. 13.
• 
capable of supporting the weight of the boiler.
• Boiler installed in a room containing bath or shower
shall be installed so person using bath or shower
cannot touch any electrical switch or boiler control
utilizing line voltage electricity.
• Multiple Boilers can be wall mounted, placed side
by side, or back to back, (common venting is not
permitted).
• Consider service clearances in all installations.
• For Direct Vent installations, air vents are not required
in room boiler is installed in, or when installed in closet
or compartment (direct vent is required).
TABLE 1: BOILER CLEARANCES
Dimension Combustible
Materials (1)
Manufacturer
Recommended
for Service(1)(2)
Top (A)
0" (0 cm) 8-5/8" (2160 mm)
Left Side (B)
1-3/4" (45 mm) 1-3/4" (45 mm)
Right Side (C)
1-3/4" (45 mm) 1-3/4" (45 mm)
Front (D)
1-9/16" (40 mm) 17-3/4"(450mm)
Back (E)
0" (0 cm) 0" (0 cm)
Bottom (F)
0" (0 cm) *9-13/16"
(250 mm)
Combustion Air/
Vent piping
0" (0 cm) 6" (160 mm)
(1) Required distances measured from boiler jacket.
(2) Service, proper operation clearance recommendation.
* Allowance for piping at the bottom of boiler not included.
WARNING
Fire Hazard! Do not install on carpeting. Failure to
follow these instructions could result in death or
serious injury.
!

protection clearances.
PN 240012363 REV. B [03/29/2019]

13
4 - LOCATING BOILER
D
13.58 in /
345.00 mm
B
A
30 in
[763 mm]
125 & 150

[345 mm]
4.2 Service and Combustible Clearances
160 & 200

[571.5 mm]
CLEARANCES REQUIRED FOR
CLOSET INSTALLATION CLEARANCES FOR COMBUSTIBLES
Top View
Back
Closet Installation
0 in /0 mm between Back of Unit and wall
Left Side View
of Boiler
Front View of Boiler
Front View of Boiler
C
F
B C
B
C
D
D
D
SERVICE CLEARANCES
CLEARANCES FOR COMBUSTIBLE MATERIALS
F
A
PN 240012363 REV. B [03/29/2019]

14
4 - LOCATING BOILER
CAUTION
Boiler weight exceeds 100 pounds (45.3 kg). Do not
lift boiler onto wall without assistance.
!
4.3 Wall Mounting
1. Decide position of boiler on the wall allowing for all

2. Mount boiler on wall using wall mounting bracket included
with unit. See Figure 4.1
3. Adjust the position of the boiler verify it is level.
4. 
5. 
the wall to side wall, then along side wall (ensure lines are
parallel and sloped properly towards the boiler, refer to

6. 
• GMHB125 & GMCB150 - 4 " [110 mm] diameter
• GMBH160 & GMCB200 - 5 " [135 mm] diameter
Note Lift boiler using chassis. Do not use front jacket,

may cause damage to the boiler.


piping can be damaged if subjected to excessive
torque.
Note
FIGURE 4-1 WALL MOUNT BRACKET (INCLUDED)
Center brackets. Avoid
overhang on sides of
wall mount bracket.
Use four (4) predrilled
holes for mounting
bracket to wall
PN 240012363 REV. B [03/29/2019]

15
5 - HYDRONIC PIPING
5.1 General
• Primary/Secondary piping required.
• Install piping in accordance with authority having
jurisdiction.
• Support system piping and safety relief valve discharge
piping. Boiler's internal piping and wall mount bracket
can be damaged if subjected to excessive weight.
NOTICE
The intended use of the internal heat exchanger pump
is a boiler loop. Do not use as a primary system pump.
• A micro bubble air elimination device is manufacturer
required.
• Size central heating pump (and domestic hot water
pump, if used) for system requirements only. Internal
heat exchanger pump compensates for pressure drop
through boiler internal piping and heat exchanger.
• 
to boiler.
• If oil is present in system water, use approved
detergent to wash system.
• It is necessary to semi-annually check the water
quality of central heating systems.
• Flush system to remove any solid objects such as metal

• Flush system until water runs clean and piping is free
of sediment.
• 
separately. If purge valves and isolation valves are not
installed, install them to properly clean the system.
Note Boiler rated at 50 psig (345 kPa) maximum
allowable working pressure. Boiler provided with
30 psig (206 kPa) safety relief valve.
WARNING
• Poison hazard. Ethylene glycol is toxic. Do not use
ethylene glycol.
• Never use automotive or standard glycol antifreeze,
even ethylene glycol made for hydronic systems.
• Ethylene glycol can attack gaskets and seals used in
hydronic systems.
• Do not use petroleum based cleaning or sealing
compounds boiler system.
• 
water.
• Use only inhibited propylene glycol solutions

with closed water heating system.
• 
glycol before installing new Boiler.
• Provide user with Material Safety Data Sheet

!
Note When installing safety relief valve it must be
installed in a vertical position with spindle at
top.
WARNING

disconnected from gas supply piping system during
any pressure testing of that system at test pressures in
excess of 1/2 psi (3.40 kPa - 34.47 mbar).
Boiler shall be isolated from the gas supply piping

during any pressure testing of gas supply piping system
at test pressures equal to or less than 1/2 psi (3.5 kPa).
Install boiler so that gas ignition system components
are protected from water (dripping, spraying,rain,
etc.) during appliance operation and service (circulator
replacement, condensate trap, control replacement,
etc.).
!
Note System pressure above 43 psi [2.96 bar] WILL
result in boiler shutting down.
FIGURE 5-1 SAFETY RELIEF VALVE
Safety Relief
Valve
TP Gauge
PN 240012363 REV. B [03/29/2019]

16
Note
• System piping exposed to freezing conditions: Use

manufacturer for use with closed water heating system.
Do not use automotive or ethylene glycol.
• Boiler installed above radiation level (or as required
by authority having jurisdiction). Integral low water
pressure switch is provided in boiler.
• Boiler used in connection with refrigeration system.
Install piping in parallel with boiler, with appropriate
valves to prevent chilled medium from entering boiler.
• System piping connected to heating coils located in air
handling unit exposed to refrigerated air circulation.

to prevent gravity circulation of boiler water during
cooling cycle.
5.2 Special Conditions
Do not expose boiler and condensate piping to
freezing temperatures.
5 - HYDRONIC PIPING
• When purging installations that include standing iron
radiators and systems with manual vents at high
points, start with nearest manual air vent. Open the

procedure, working toward furthest air vent.
• Install a basket strainer if large amounts of sediment is
present. Keep basket clear of sediment build up.
• Manufacturer recommends a water treatment product
be used for sediment removal.
• Install a magnetic dirt separator in the hydronic
system where there are cast iron or steel components,
or where the previous boiler was a cast iron heat


surfaces and accumulate in pump cavities causing

• Ensure piping in the heating system has an oxygen
barrier.
• If using antifreeze solution do not exceed 50% glycol.
PN 240012363 REV. B [03/29/2019]

17
WARNING
Burn and scald hazard. Safety relief valve could
discharge steam or hot water during operation.
Install discharge piping per these instructions.
!
5 - HYDRONIC PIPING
5.3 Safety Relief Valve and Air Vent
• Install safety relief valve. See Figure 5-2.
• Install safety relief valve with spindle in vertical
position.
• 
relief valve.
• Install discharge piping from safety relief valve. Do not
use plastic pipe.
• Use ¾" or larger pipe.
• Use pipe suitable for temperatures of 375°F (191°C) or
greater. Do not use plastic pipe on safety relief valve.
• Individual boiler discharge piping shall be independent
of other discharge piping.
• Size and arrange discharge piping to avoid reducing
safety relief valve relieving capacity below minimum
relief valve capacity stated on rating plate.
• Run pipe as short and straight as possible to location
protecting user from scalding and properly drain piping.
• Install union, if used, close to safety relief valve outlet.
• Install elbow(s), if used, close to safety relief valve
outlet and downstream of union (if used).
• Terminate pipe with plain end (not threaded).
FIGURE 5-2 SAFETY RELIEF VALVE DISCHARGE PIPING
WARNING
Burn and scald hazard. Safety relief valve could
discharge steam or hot water during operation.
Use pipe suitable for temperatures of 375°F (191°C) or
greater. DO NOT use plastic pipe.
!
Check Local
Codes For
Maximum
Distance To Floor
Safety Relief
Valve
Do not use
plastic pipe see
Warning below.
PN 240012363 REV. B [03/29/2019]
TP Gauge

18
5.4 Trim Piping
• Temperature - Pressure Gauge. Install temperature
pressure gauge. See Figures 5-1 and 5-2.
• Some boiler models may have integral drain valve located
inside jacket directly underneath pump. Install provided
external drain valve as required.
5.5 System Piping
• Ensure caps are removed from boiler water connections.
• 
• 
prevention device.
• Single boiler system. See Figure 5-6 for general guidance.
Additional considerations:
• Boiler control does not accommodate central heating
pump. Installer is responsible for integration of

• Boiler control allows domestic hot water
prioritization. Function could be lost if central heating
pump is not directly connected to zone control system.
• Multiple boiler system. Considerations:
• Field sourced control system logic may require
equivalent water temperatures entering each boiler
to properly sequence and adjust system supply
temperature.
WARNING
Burn and scald hazard. Verify all plastic caps are
removed from boiler connections. Failure to follow
these instructions could result in death or serious
injury.
!
• Thoroughly ush all hydronic piping. Flush system
(wash) clean after installing all piping. Debris or cutting
oils, etc., left inside system will reduce heat transfer in






• 
• Connect system valve pipe work to the boiler.
• 
Follow local code with respect to necessary distance to the
 See Figure 5-2.
• Verify all valves are closed.
5 - HYDRONIC PIPING
5.6 External Optional Low Water Cut O
These guidelines are supplied when necessary to install an

level condition in a boiler, as required by the Authority Having
Jurisdiction.
Follow LWCO manufacturer installation instructions for type of
LWCO selected in addition to these instructions.
LWCO shall be 120V/60HZ control and dry contacts sized for
load being connected. Wire control to boiler. See Figure 5-4.
Connect LWCO device to the system ground. Ground in
accordance with the requirements of the authority having
jurisdiction or, in the absence of such requirements, with the
National Electrical Code (NEC) or Canadian Electrical Code
CEC.
• Locate LWCO sensing device in the supply piping, or in

height of boiler. See Figure 5-3, Piping Diagram.
• Position control in HORIZONTAL piping to assure proper
boiler protection (upright or 90° rotation).
• For proper operation, sensing element of the LWCO
control shall be positioned in the tee to sense the main
water stream. Maintain minimum 1/4” spacing from pipe
walls. Element shall NOT contact the rear, or side walls of
the tee. See Figure 5-5.
• Install an air vent using a tee to avoid nuisance
shutdowns.
• Apply small amount of pipe sealant to threaded
connections.
• Arrange piping to prevent water dripping onto boiler.
• 
LWCO sensing device.
• Manufacturer recommends installing an isolation and purge
valve to use during commissioning to ensure the boiler
does not shut down due to over temperature. See Figure
5-3 for details.
• 
installed LWCO.
PN 240012363 REV. B [03/29/2019]

19
FIGURE 5-3 - PIPING DIAGRAM - LWCO LOCATION
5 - HYDRONIC PIPING
Air Vent
Supply
Gas
Boiler
Safety Relief
Valve
Position LWCO Above
Top of Boiler
DO NOT PLACE ISOLATION VALVE
BEFORE TEE OR LWCO.
*To Drain
* Check Local Codes
for Maximum Distance
to Floor.
Arrange piping to prevent
water dripping onto boiler.
Return
Low Water Cuto (LWCO)
Installation if required by the
Authority Having Jurisdiction
(See Figure 5-5 for detail)
Magnetic
Dirt
Separator
Purge Valve
Purge Valve
1
1
Note
PN 240012363 REV. B [03/29/2019]
Note
Illustrations are meant to
show system piping concept
only. Installer is responsible
for all equipment and detailing
required by authority having
jurisdiction.
Note

20
NO
NO
YES
FIGURE 5-5 - LOW WATER CUTOFF - DETAIL
5 - HYDRONIC PIPING

Electrical Conduit
J-Box
120 V/60 HZ
Conduit or Power
Supply cord
(Polarized)
L1
N
G
GND
L1
N
GND
BLK
WHT
120 V/60 HZ Socket
(Polarized) 120 V/60 HZ
Cord Set From Boiler
N.O
FIGURE 5-4 - LWCO WIRING DIAGRAM
PN 240012363 REV. B [03/29/2019]