UTICA BOILERS UBSSC-299 Instruction manual

WALL MOUNTED
GAS BOILER
INSTALLATION, OPERATION &
MAINTENANCE MANUAL
Models
UBSSC-050
UBSSC-075
UBSSC-100
UBSSC-150
UBSSC-200
UBSSC-299
050/075/100
SIZE SHOWN
Manufactured by:
ECR International Inc.
2201 Dwyer Avenue, Utica, NY 13501
Tel. [phone]
www.ecrinternational.com
PN 240011320 REV. G [10/01/2021]

2
VERIFY CONTENTS RECEIVED
* Boiler provided with 30 psig (206 kpa) safety relief valve. Field source safety relief valve if system pressure greater than 25
psig.
** Boiler provided with 75 psig temperature pressure gauge. Field source temperature pressure gauge if system pressure
greater than 60 psig.
Fully Assembled Boiler
(50-100 size shown)
Metal Wall Bracket
w/ Lag Bolt, 3/8" x 3" Hex
(4 ea)
*Safety Relief Valve
w/ 3/4" Tee, 3/4" Nipple,
3/4" x 1/4" Elbow
and Air Vent
**Temperature
Pressure Gauge
w/ 3/4" x 1/4" Bushing,
3/4" Nipple, 1¼ x 5½ 4"
Tee,
Used for electrical wire
knockouts
Used for packaging holes on
back of boiler
Used for packaging holes on
back of boiler
Drain Valve, 3/4", 3/4"
Tee, 3/4" Tee
Bushing 7/8" OD, Heyco
(2 ea)
Stopper, Rubber 5/16" (2
ea) Plastic Plug (2 ea)
Used for measuring outside
temperature
11" x 17" Page for critical
installation issues. Includes essential documents.
Outdoor Sensor Critical Installation
Instruction Document Package
PN 240011320 Rev. G 10/01/2021]

3
TABLE OF CONTENTS
1 - Important Safety Information.........................6
2 - Introduction....................................................7
3 - Component Listing ..........................................8
4 - Locating Boiler ..............................................12
5 - Hydronic Piping.............................................14
5.2 Special Conditions.......................................14
5.3 Safety Relief Valve And Air Vent....................15
5.4 Trim Piping.................................................16
5.5 System Piping ............................................16
6 - Combustion Air And Vent Piping....................23
6.2 Removal Of Existing Boiler From Common Vent
System.........................................................23
6.3 Materials ..................................................23
6.4 Pipe Installation..........................................24
6.5 Termination................................................24
6.6 Venting Congurations.................................25
6.7 Side Venting Terminal Requirements..............30
6.8 Multiple Boiler Venting Installation ................32
6.9 Condensate Piping ......................................33
7 - Gas Supply Piping .........................................34
8 - Electrical Connections ...................................36
8.3 Line Voltage Connections .............................36
8.4 External Connections...................................36
9 - Start Up Procedure........................................38
9.6 Perform CSD-1 Compliance Test.......................40
9.7 Complete Start Up Procedure ...........................41
10 - Operating Instructions ................................45
11 - General Maintenance And Cleaning .............46
12 - Ratings And Capacities................................49
13 - Trouble Shooting.........................................50
14 - Wiring Diagram ...........................................67
15 - Glossary ......................................................71
Appendix A - Control Module .............................. 73
1.1 Introduction ...............................................73
1.2 Operation ..................................................73
1.3 Status Indication ........................................73
1.4 Sequence of Operation ................................74
1.5 User Menu .................................................76
PN 240011320 Rev. G 10/01/2021]

4
Table 1: Physical Data
Models 050/075/100 150/200 299
Width (A) 20" (508mm) 23" (584mm)
Height (B) 31" (787mm) 42" (1067mm)
Depth (C) 14-¾" (375mm) 16.0" (406mm) 18.4" (467mm)
Bracket (D) 27.7" (704mm) 38.7" (983mm)
Height (E) 32" (813mm) 43" (1092mm)
Water
Connections
Size (F) 1-1/4" NPT 1-1/4" NPT
Location (G) 2" (51mm) 2" (51mm) 3" (51mm)
Location (H) 5" (127mm) 3" (76mm) 2.6" (66mm)
Location (I) 3-½" (89mm) 4-½ (112mm) 4-¾" (114mm)
Gas
Connection
Location (J) 4-⁷/₈(124mm) 7-¾ " (197mm)
Size (K) 1/2" NPT 3/4" NPT
Condensate Drain Connection (L) 3/4" NPT 3/4" NPT
Weight
Shipping 111 lb (50 kg) ~182 lb (83 kg) ~225 lb (102 kg)
Unit 91 lb (41 kg) ~157 lb (71kg) ~195 lb (89 kg)
Vent Connector 2" (51mm) 3" (76mm)
PHYSICAL DATA
PN 240011320 Rev. G 10/01/2021]

5
Dimensions
Condensate Drain Connection (L)
Return Water (F)
Gas Connection (K)
Vent Connector
Combustion Air
Safety Relief Valve
Connection (¾ NPT)
A
B
E
Front View Rear View
D
Wall Bracket
Top View 50-200
Bottom View
Dimensions
50-100 MBH
Bottom View
Connection
Identication 150-299 MBH
Supply Water (F)
IH
G
C
J
PHYSICAL DATA
Condensate Drain Connection (L)
Return Water (F)
Gas Connection (K)
Bottom View
Connection
Identication 50-100 MBH
Supply Water (F)
Bottom View
Dimensions
150-200 MBH
IH
C
J
Vent Connector
Combustion Air
Safety Relief Valve
Connection (¾ NPT)
Top View 299
Bottom View
Dimensions
299 MBH
I
C
G
J
G
H
PN 240011320 Rev. G 10/01/2021]

6
1 - IMPORTANT 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.
Boiler installation shall be completed by qualied agency. See
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
CAUTION
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 gas supplier’s instructions.
• If you cannot reach your gas supplier, call the re
department.
!!
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.
!!
PN 240011320 Rev. G 10/01/2021]

7
Information and specications outlined in this manual in eect at the
time of printing of this manual. reserves the right to
discontinue, change specications or system design at any time without
notice and without incurring any obligation, whatsoever.
2 - INTRODUCTION
2.4 Designated Use
• Hot water heating boiler.
• Indoor installation.
• Closet or alcove installation.
• Direct vent boiler.
• For use with natural gas or liqueed petroleum gases
(LP/propane).
2.5 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).
• Exceed 150 psig (1.03 MPa) maximum allowable working
pressure.
• Exceed 195°F (90.5°C) system design temperature.
2.6 Operational Features
• Modulating: 20-100%.
• Integral Dual Limit.
• Integral Low Water Cuto (with test button).
• Outdoor Temperature Reset.
• Integral Multiple Boiler Control.
• Heat exchanger over heat protection.
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.
Additional manual reset low water cuto may be required.
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:
Installation by licensed plumber or gas tter.
PN 240011320 Rev. G 10/01/2021]

8
3.1 Component Listing - Refer to diagrams on
following pages.
1. User Interface Displays information regarding boiler
condition. Allows adjustment of boiler operating
parameters. NOTE: Does not replace thermostat used to
control central heating space.
2. Combustion Air Inlet (2"/3") See section 6.
3. Return Water From Heating System (In) Connection
supplied at bottom of boiler. See section 5.
4. Low Voltage Terminal StripLow Voltage Terminal Strip ConnectionConnection of all low voltage
wiring, including thermostat.
5. Igniter
6. Flame Sensor
7. Sight Glass permits observation of burner ame.
8. Burner (see page 43)
9. Heat Exchanger
10. Condensate Collector
11. Return Water Temperature Sensor
12. Drain Valve (see page 16)
13. Internal Primary Loop Ball Valve
14. Supply Water Outlet to Heating System (Out)
Connections supplied for connecting from bottom of
boiler. See section 5.
15. Vent Temperature Sensor
16. Condensate Drain Boiler produces a liquid
(condensate) as a by-product of combustion. Condensate
must be piped to appropriate drain. See section 6.
17. Heat Exchanger PumpHeat Exchanger Pump
18. Gas Shuto ValveGas Shuto Valve Fuel supply isolation during servicing.Fuel supply isolation during servicing.
See section 7See section 7
19. Combustion Air BlowerCombustion Air Blower Delivers proper quantity ofDelivers proper quantity of
combustion air, receives fuel from gas valve, mixes aircombustion air, receives fuel from gas valve, mixes air
and fuel sending mixture to burner for combustion.and fuel sending mixture to burner for combustion.
20. Gas (Control) ValveGas (Control) Valve DeliversDelivers proper quantity of fuel toproper quantity of fuel to
Combustion Air Blower. See section 7.Combustion Air Blower. See section 7.
21. Supply Water Temperature Sensor and High LimitSupply Water Temperature Sensor and High Limit
SwitchSwitch
22. Low Water CutoffLow Water Cutoff Senses inadequate quantity ofSenses inadequate quantity of
water. Turns o boiler before damage can occur.water. Turns o boiler before damage can occur.
23. Safety Relief Valve Factory supplied, Field installed. See
section 5.
24. High Voltage Junction Box For connection of 120V
components. See section 88.
25. Vent Connector See section 6.
26. Gas ConnectionGas Connection See section 7.See section 7.
27. Wall Hanging Support Bracket (see page 13) Integral
to boiler. Allows wall mounting when used with
supplied wall mounting bracket. See section 4.
28. Air Vent
29. Boiler Control ModuleBoiler Control Module
30. Transformer Supplies 24V power to low water cuto.
31. Flue Air Mixture Pressure Test Port - Not available on all
models.
32. Combustion Analysis Test Port
33. Internal Pump Relay - Not available on all models.
34. Heat Exchanger Surface Temperature Switch
35. ASME Plate
3 - COMPONENT LISTING
PN 240011320 Rev. G 10/01/2021]

9
FIGURE 3-1 Boiler Components (Viewed from Back of Boiler)
Vent Connector
Combustion Air Inlet
Safety Relief ValveSafety Relief Valve
Air VentAir Vent
Wall Mount Support BracketWall Mount Support Bracket
3 - COMPONENT LISTING
FIGURE 3-2 Jacket Removal -Viewed from Bottom of
Boiler (50-100 MBH shown)
Jacket LatchJacket Latch
Lift latch to dis-engageLift latch to dis-engage
Bottom of Boiler
FIGURE 3-3 Jacket Removal -Viewed from Left Side of
Boiler (50-100 MBH shown)
Dis-engage latch liftDis-engage latch lift
jacket up and o jacket up and o
jacket supportjacket support
Jacket Support (Lip)Jacket Support (Lip)
Jacket LatchJacket Latch
Note
PN 240011320 Rev. G 10/01/2021]

10 PN 240011320 Rev. G 10/01/2021]
FIGURE 3-4 Boiler Components 50/75/100 MBH (View from Front of Boiler) As seen on front cover
3 - COMPONENT LISTING
User InterfaceUser Interface
Behind User Interface
See Section 5 For Piping Instructions
Note
Gas Shuto ValveGas Shuto Valve
(Shown In Open Position)
Vent Connector
Combustion Air BlowerCombustion Air Blower
Gas (Control) ValveGas (Control) Valve
Low Water CutoLow Water Cuto
Air VentAir Vent
Combustion Air Inlet
Heat Exchanger PumpHeat Exchanger Pump
Condensate Trap
Return Water FromReturn Water From
Heating System (In)Heating System (In)
Supply Water To HeatingSupply Water To Heating
System (Out)System (Out)
Low Voltage Terminal StripLow Voltage Terminal Strip
Vent Temperature Sensor
Gas ConnectionGas Connection
Combustion Analysis Test PortCombustion Analysis Test Port
High Voltage Junction BoxHigh Voltage Junction Box
Heat ExchangerHeat Exchanger
Boiler Control Module
Fuse And Holder
IgniterIgniter
Flame Sensor
Sight GlassSight Glass
Flue Air Mixture PressureFlue Air Mixture Pressure
Test PortTest Port
Condensate DrainCondensate Drain
TransformerTransformer
Return Water TemperatureReturn Water Temperature
SensorSensor
Internal Primary Loop Ball ValveInternal Primary Loop Ball Valve
Heat Exchanger SurfaceHeat Exchanger Surface
Temperature SwitchTemperature Switch
ASMEASME PlatePlate
Supply Water Temperature
Sensor & High Limit Switch
Safety Relief ValveSafety Relief Valve
Low Water CutoLow Water Cuto
Condensate CollectorCondensate Collector

11 PN 240011320 Rev. G 10/01/2021]
FIGURE 3-55 Boiler Components 299 MBH (View from Front of Boiler)
3 - COMPONENT LISTING
Gas Shuto ValveGas Shuto Valve
(Shown In Open Position)(Shown In Open Position)
Vent ConnectorVent Connector
Gas (Control) ValveGas (Control) Valve
Supply WaterSupply Water
Temperature Sensor &Temperature Sensor &
High Limit SwitchHigh Limit Switch
Safety Relief ValveSafety Relief Valve
Combustion Air InletCombustion Air Inlet
Heat Exchanger PumpHeat Exchanger Pump
Return Water FromReturn Water From
Heating System (In)Heating System (In)
Supply Water To HeatingSupply Water To Heating
System (Out)System (Out)
Low Voltage Terminal StripLow Voltage Terminal Strip
Combustion Analysis TestCombustion Analysis Test
PortPort
Gas ConnectionGas Connection
High Voltage JunctionHigh Voltage Junction
BoxBox
Heat ExchangerHeat Exchanger
Boiler Control ModuleBoiler Control Module
Fuse and HolderFuse and Holder
Flame SensorFlame Sensor
Condensate DrainCondensate Drain
TransformerTransformer
User InterfaceUser Interface
Internal Primary LoopInternal Primary Loop
Ball ValveBall Valve
(Behind Control)(Behind Control)
Blower VenturiBlower Venturi
Heat Exchanger SurfaceHeat Exchanger Surface
Temperature SwitchTemperature Switch
Internal Pump RelayInternal Pump Relay
Sight Glass & IgniterSight Glass & Igniter
Vent Temperature SensorVent Temperature Sensor
Return TemperatureReturn Temperature
SensorSensor
(Behind User Interface)(Behind User Interface)
Asme PlateAsme Plate
Air VentAir Vent
Low Water CutoLow Water Cuto
Condensate CollectorCondensate Collector
Note See Section 5 For Piping Instructions

12
4 - LOCATING BOILER
FIGURE 4-1 Clearance to Combustible Materials
4.1 Boiler Location Considerations
• Ambient room temperature always above 32°F (0°C) to
prevent freezing of liquid condensate.
• Approved for installation in closets.
• Protect gas ignition system components from water
(dripping, spraying, rain, etc.) during operation and
service (circulator replacement, condensate trap, control
replacement, etc.).
• Wall mount only.
• 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 2 and gure 4-1.
• Multiple Boilers can be wall mounted, placed side by
side, or back to back.
TABLE 2: BOILER CLEARANCES
Dimension Combustible
Materials (1) Service(1)(2)
Model 050/075/100/150/200/299
Top (A) 0" (0 cm) 14" (36 cm)
Left Side (B)) 0" (0 cm) 0" (0 cm)
Right Side (C) 0" (0 cm) 0" (0 cm)
Front (D) 0" (0 cm) 6" (16 cm)
Back (E)
0" (0 cm) 0" (0 cm)
Bottom (F)
0" (0 cm) 12" (32 cm)
Combustion Air/Vent
piping
0" (0 cm) 6" (16 cm)
Hot Water Piping See local code 6" (16 cm)
(1) Required distances measured from boiler jacket.
(2) Service, proper operation clearance recommendation.
A
E
ED
A
CB
A
FLOOR FLOOR
FFF
F
Boiler Front View Boiler Left Side View
PN 240011320 Rev. G 10/01/2021]

13
4 - LOCATING BOILER
CAUTION
Boiler weight exceeds 75 pounds (34 kg). Do not lift
boiler onto wall without assistance.
!!
4 Slots for attaching4 Slots for attaching
Wall Mount Bracket toWall Mount Bracket to
StudsStuds
Center brackets. Avoid overhang on sides of wallCenter brackets. Avoid overhang on sides of wall
mount bracket.mount bracket.
FIGURE 4-3 Low Water Cuto Orientation
5° ~ 15°
FactoryFactory
Default 10°Default 10°
WARNING
Fire, explosion hazard. Mount boiler vertically or
slightly tilted backward to insure proper function of
low water cuto. Failure to follow these instructions
could result in death or serious injury.
!
4.2 Pre-pipe supply and return water connections with factory
ttings before wall mounting.
4.3 Wall Mounting
Mount boiler on wall using wall mounting bracket included
with unit.
• Structure must be capable of supporting boiler weight
plus 60 lbs (28 kg). See Table , page 4.
• Wall mount bracket has 4 slots allowing mounting on
two (2) wall studs spaced at 11½" to 16½" on center.
See gure 4-2.
• Boiler includes (4) 3/8" x 3" lag screws and (4)
washers for attaching wall mount bracket to wood
studs. Field source appropriate fasteners for other wall
constructions (masonry, concrete).
• Attach wall mount bracket level on wall.
• Boiler must engage with wall mount bracket.
• Avoid overhang on sides of wall mount bracket. Verify
boiler bracket is centered on wall bracket. See gure
4-2.
• When mounting boiler onto wall insert two plastic
stoppers and two plastic plugs to packaging holes on
back of boiler. See parts listed on page 2.
• Mount boiler vertically or slightly tilted backward to
insure the low water cuto functions properly. See
gure 4-3 for low water cuto orientation.
Note
Note
Lift boiler using chassis. Using front jacket, vent
piping, water or gas ttings to lift boiler may cause
damage to the boiler.
Use two (2) wrenches when tightening and tting to
pipe boiler's threaded ttings. Boiler's internal piping
can be damaged if subjected to excessive torque.
Note
FIGURE 4-2 Wall Mount Bracket Engaged with
Bracket on Boiler
PN 240011320 Rev. G 10/01/2021]

14
5 - HYDRONIC PIPING
5.1 General
• 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.
• 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.
• Thoroughly clean and ush system before connecting to
boiler.
• If oil is present in system water, use approved detergent
to wash system.
• Flush system to remove any solid objects such as metal
chips, bers, or Teon tape, etc.
5.2 Special Conditions
Note
• System piping exposed to freezing conditions: Use
inhibited propylene glycol solutions certied by uid
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 cuto
provided in boiler. See pages 10 & 11.
• 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.
Install ow control valves or other automatic means to
prevent gravity circulation of boiler water during cooling
cycle.
FIGURE 5-1 Safety Relief Valve & Air Vent (Viewed
from front of boiler)
Safety ReliefSafety Relief
ValveValve
3/4" x 4 NPT3/4" x 4 NPT
NippleNipple
3/4" x 1/4"3/4" x 1/4"
NPT 90°NPT 90°
ElbowElbow
3/4"F x M x3/4"F x M x
F NPT TeeF NPT Tee
Air VentAir Vent
Note Boiler rated at 150 psig (1.03 MPa) maximum
allowable working pressure. Boiler provided with
30 psig (206 kPa) safety relief valve. Field source
safety relief valve for system pressures greater
than 25 psig. Temperature Pressure Gauge
satisfactory for 60 psig operation. Field source
temperature pressure gauge for system pressures
greater than 60 psig.
Note Position Air Vent and Safety Relief Valve to provide
space for discharge piping.
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.
• Use only inhibited propylene glycol solutions
certied by uid manufacturer as acceptable for
use with closed water heating system.
• Thoroughly clean and ush any system that used
glycol before installing new Boiler.
• Provide user with Material Safety Data Sheet
(MSDS) on uid used.
!
Do not expose boiler and condensate piping to
freezing temperatures.
PN 240011320 Rev. G 10/01/2021]

15
WARNING
Burn and scald hazard. Safety relief valve could
discharge steam or hot water during operation.
Install discharge piping per these instructions.
!
FIGURE 5-2 Safety Relief Valve Discharge Piping
Safety Relief Valve
5 - HYDRONIC PIPING
5.3 Safety Relief Valve and Air Vent
• Install safety relief valve and air vent using pipe ttings
provided with boiler. See gure 5-1
• Install safety relief valve with spindle in vertical position.
• Do not install shuto valve between boiler and safety
relief valve.
• Install discharge piping from safety relief valve. See
gure 5-2.
• Use ¾" or larger pipe.
• Use pipe suitable for temperatures of 375°F (191°C) or
greater.
• 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).
Check Local Codes ForCheck Local Codes For
Maximum Distance ToMaximum Distance To
FloorFloor
[50-100 Size Shown]
PN 240011320 Rev. G 10/01/2021]

16
5.4 Trim Piping
• Temperature - Pressure Gauge. Install temperature
pressure gauge using nipple, tee and bushing provided with
boiler. See gure 5-3.
• Drain Valve. Install drain valve using nipple, tee and
bushing provided with boiler. See gure 5-3.
5.5 System Piping
• See Table 3 for basic system piping congurations.
• Systems with automatic ll valves require back ow
prevention device.
• Single boiler system. See gures 5-5, 5-6, 5-7A, & B for
general guidance. Additional considerations:
• Boiler control is designed for single central heating
pump. Installer responsible for integration of
multiple central heating pumps.
• Boiler control allows domestic hot water
prioritization. Function could be lost if central heating
pump not directly connected to control system.
• Multiple boiler system. See gure 5-8A, B & C for general
guidance. Additional considerations:
• Control system requires equivalent water
temperatures entering each boiler to properly sequence
and adjust system supply temperature.
• Install multi boiler sensor kit. See "Parts, Kits &
Optional Accessories" manual for part number.
• Heating system with existing primary loop, close internal
primary loop ball valve.
• Heating system without existing primary loop, leave internal
primary loop ball valve open to use internal primary loop.
FIGURE 5-3 Temperature Pressure Gauge and Drain
Valve Installations
Temperature
Pressure Gauge
shown at System
Supply Connection
Drain Valve shown
at System Return
Connection to
Boiler
Gas Supply
5 - HYDRONIC PIPING
PN 240011320 Rev. G 10/01/2021]

17
Piping Legend
FIGURE 5-4 System Piping
System
Return
System
Supply
Safety Relief Valve
WALL
MOUNTED
ONLY
Table 3 - System Piping Congurations
Single Boiler
Two Pipe Zoned System With Zone Valves gure 5-5
With Zone Pumps gure 5-6
Primary/Secondary Pumping Closed External Primary Loop gure 5-7A
Open External Primary Loop gure 5-7B
Multiple Boilers
Two Pipe Zoned System With Zone Valves gure 5-8A
With Zone Pumps Not Shown
Primary/Secondary Pumping
Closed External Primary Loop gure 5-8B
Open External Primary Loop gure 5-8C
5 - HYDRONIC PIPING
Note
Illustrations are meant to show system piping
concept only. Installer responsible for all
equipment and detailing required by authority
having jurisdiction.
Check Local
Codes For
Maximum
Distance To
Floor
PN 240011320 Rev. G 10/01/2021]

18
FIGURE 5-5 Single Boiler Two-Pipe Zoned System With Zone Valves
FIGURE 5-6 Single Boiler Two-Pipe Zoned System With Zone Pumps
DHW
Pump
5 - HYDRONIC PIPING
3/8"/10mm Open
End Wrench may
be required to
turn valve
Heat exchanger
ball valve open (as
shipped)
CH/System
Pump
Heat exchanger
ball valve open (as
shipped)
DHW
Pump
Zone
Pump
3/8"/10mm Open
End Wrench may
be required to
turn valve
PN 240011320 Rev. G 10/01/2021]

19
FIGURE 5-7A Single Boiler Using Primary/Secondary Pumping With Closed External Primary Loop
FIGURE 5-7B Single Boiler Using Primary/Secondary Pumping With Open External Primary Loop
CH/System
Pump
12"(305mm) Maximum
separation
12"(305mm)
Maximum
separation
5 - HYDRONIC PIPING
Heating system
with existing
primary loop.
Internal primary
loop ball valves
closed
Existing closely spaced tees
in primary system loop
Limit length
to
5' (1.6m)
3/8"/10mm Open
End Wrench may
be required to
turn valve
12"(305mm) Maximum
separation
12"(305mm)
Maximum
separation
Existing closely spaced tees
in primary system loop
Limit length
to
5' (1.6m)
3/8"/10mm Open
End Wrench may
be required to
turn valve
CH/System
Pump
Internal primary
loop ball valves
open. Heating
system without
existing primary
loop.
PN 240011320 Rev. G 10/01/2021]

20
5 - HYDRONIC PIPING
PN 240011320 Rev. G 10/01/2021]
(See Multiple Boiler Guide)
FIGURE 5-8A Multiple Boiler Using Primary Secondary Two Pipe Zoned System With Zone Valves
Up to 16
boilers
DHW
Pump
CH/System
Pump 12"/305mm Maximum Separation
System
Temperature
Sensor
Size common piping
per maximum heat
capacity of entire
system
All internal
primary loop ball
valves closed
Limit
length to
5' (1.6m)
3/8"/10mm Open
End Wrench may
be required to turn
valve