HELIX VX-050 Instruction manual

WALL MOUNTED
GAS BOILER
INSTALLATION, OPERATION &
MAINTENANCE MANUAL
An ISO 9001-2008 Certied Company P/N# 240010618, Rev. B [08/2014]
Models
VX-050
VX-075
VX-100
VX-150
VX-200
Manufactured by:
ECR International, Inc.
2201 Dwyer Avenue, Utica NY 13501
web site: www.ecrinternational.com

2
VERIFY CONTENTS RECEIVED
Description
Item No. Illustration
Fully Assembled Boiler 1
Metal Wall Bracket 2
Lag Bolt, 3/8" x 3" Hex (4 ea) 3
*Safety Relief Valve 4
Condensate Trap
Height 12.45" [316mm] 5
**Temperature Pressure Gauge 6
Bushing 3/4" x 1/4" 7
3/4" FNPT Adapter 8
3/4" Tee (Same as No. 10) 9
3/4" Tee 10
3/4" FNPT Adapter 11
Drain Valve, 3/4" 12
1/2" Gas Shutoff Valve
(shown in open position) 13
Bushing 7/8" OD, Heyco (2 ea) 14 Used for electrical wire knockouts.
Stopper, Rubber 5/16" (2 ea) 15 Used for packaging holes on back of boiler.
Plastic Plug (2 ea) 16 Used for packaging holes on back of boiler.
Outdoor Sensor 17 Used for measuring outside temperature.
Critical Installation Instruction 18 11" x 17" Page for critical installation issues.
Document Package 19 Includes essential documents.
4
2
3
5
6
8
12
11
7
10
* 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.
SIZE
SHOWN
050/075/100
1
9
13

3
OVERALL DIMENSIONS
Table 1 : Physical Data
Models 050/075/100 150/200
Width (A) 20" (508mm) 23" (584mm)
Height - Unit only (B) 27.75" (705mm) 37.75" (959mm)
Depth (C) 14.75" (375mm) 16.3" (414mm)
Bracket (D) 24.41" (620mm) 35.6" (904mm)
Height unit w/ Piping (E) 30.75" (781mm) 40.75" (104cm)
Height unit w/vent (L) 31" (787mm) 41.8" (106cm)
Height unit from vent w/piping
supply & return (M) 33.94" (862mm}
44.75" (114cm)
Water
Connections
Size (F) 3/4" Type L Copper 1" Type L Copper
Location (G) 2.22" (56.4mm) 2" (51mm)
Location (H) 2.33" (59mm) 3" (76mm)
Location (I) 9.32" (237mm) 11" (279mm)
Gas
Connection
Location (J) 3.06" (77.7mm) 4.6" (117mm)
Size (K) 1/2" NPT 3/4" NPT
Condensate Drain Connection (I) 3/4" NPT 3/4" NPT
Weight Shipping 135 lb (61 kg) ~200 lb (91kg)
Unit 75 lb (34kg) ~127 lb (58kg)
Vent Connector 2" (51mm) 3" (76mm)
LEFT SIDE
OF BOILER
(D)
Wall Hanging
Bracket
(D) (A)
(B)
Vent Connector Combustion Air
Safety Relief
Valve
Connection
(¾ NPT)
(E)
(G)
(C)
(J)
(H) (I)
Gas Connection
W i r e
Knockouts
Supply Water
to Heating
System
Return Water
from Heating
System
Condensate
Drain
(L)
(M)
BOTTOM OF BOILER
BOTTOM OF BOILER
TOP OF BOILER
FRONT OF BOILER RIGHT SIDE
OF BOILER
BACK OF BOILER

4
1 - Introduction...............................................................................................................................5
2 - Important Safety Information....................................................................................................6
3 - Component Listing .....................................................................................................................7
4 - Locating Boiler ......................................................................................................................... 11
5 - Hydronic Piping........................................................................................................................ 13
5.2 Special Conditions ................................................................................................................. 13
5.3 Safety Relief Valve and Air Vent .............................................................................................. 13
5.4 Trim Piping ........................................................................................................................... 14
5.5 System Piping....................................................................................................................... 14
6 - Combustion Air And Vent Piping...............................................................................................21
6.2 Removal of Existing Boiler From Common Vent System 21
6.3 Venting Materials ................................................................................................................. 21
6.4 Vent Pipe Installation ............................................................................................................. 22
6.5 Vent Termination .................................................................................................................. 22
6.7 Venting Congurations ........................................................................................................... 23
6.8 Side Venting Terminal Requirements of : .................................................................................. 28
6.9 Multiple Boiler Venting Installation ........................................................................................... 30
6.10 Condensate Piping ............................................................................................................... 30
7 - Gas Supply Piping ....................................................................................................................31
8 - Electrical Connections ..............................................................................................................33
8.3 Line Voltage Connections ....................................................................................................... 33
8.4 External Connections ............................................................................................................. 33
9 - Start Up Procedure................................................................................................................... 35
9.6 Perform CSD-1 Compliance Test ..................................................................................................... 39
9.7 Complete Start Up Procedure ......................................................................................................... 40
10 - Operating Instructions ...........................................................................................................41
11 - General Maintenance And Cleaning ........................................................................................42
12 - Ratings And Capacities...........................................................................................................44
13 - Trouble Shooting.................................................................................................................... 45
13 - Trouble Shooting (Temperature Resistance Chart)............................................................62
14 - Wiring Diagram ......................................................................................................................63
15 - Glossary .................................................................................................................................67
APPENDIX A - CONTROL MODULE....................................................................................................69
1.1 Introduction ........................................................................................................................ 69
1.2 Operation ........................................................................................................................... 69
1.3 Status Indication ................................................................................................................. 69
1.4 Sequence of Operation ......................................................................................................... 70
1.5 User Menu .......................................................................................................................... 72
OPTIONAL USER INTERFACE RELOCATION......................................................................................82
PRIMARY LOOP EQUIVALENT LENGTH CALCULATIONS & PUMP SELECTION...............................83-86
TABLE OF CONTENTS

5
1.1 Designated Use
• Hot water heating boiler.
• Indoor installation.
• Closet or alcove installation.
• Direct vent or single vent pipe boiler.
• For use with natural gas or liqueed petroleum gases
(LP/propane).
1.2 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.
1.3 Operational Features
• Modulating: 20-100%.
• Integral Dual Limit.
• Connection provided for required eld sourced low water
cutoff (LWCO).
• Outdoor Temperature Reset.
• Integral Multiple Boiler Control.
• Heat exchanger over heat protection.
• Alternate mounting of User Interface
Information and specications outlined in this manual in effect at the
time of printing of this manual. ECR International reserves the right to
discontinue, change specications or system design at any time without
notice and without incurring any obligation, whatsoever.
Check our website frequently for updates: www.ecrinternational.com
1 - INTRODUCTION

6
NOTICE
Used to address practices not related to personal
injury.
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.
2.2 Become familiar with symbols identifying
potential hazards.
2.1 General
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.
!
2.3 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.
• Canada
• Natural Gas and Propane Installation Code,
CAN/CSA B149.1.
• Canadian Electrical Code, Part I, Safety Standard
for Electrical Installations, CSA C22.1
2.4 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 cutoff may be required.
2.5 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.
2 - IMPORTANT SAFETY INFORMATION

7
3.1 Component Listing - Refer to diagrams on
following pages.
1. Gas Shutoff Valve (Field Installed) Fuel supply
isolation during servicing. Factory supplied, Field installed.
See section 7.
2. Vent Connector See section 6.
3. Combustion Air Inlet (2"/3") See section 6.
4. Igniter
5. Flame Sensor
6. Sight Glass Permits observation of burner ame.
7. Flue Air Mixture Pressure Test Port - Not available
on all models.
8. User Interface Displays information regarding boiler
condition. Allows adjustment of boiler operating
parameters. NOTE: Does not replace thermostat used
to control central heating space.
9. Boiler Control Module
10. Heat Exchanger
11. ASME Plate
12. Low Voltage Terminal Strip Connection of all low
voltage wiring, including thermostat.
13. Return Water Temperature Sensor
14. Return Water From Heating System (In) and
Drain Valve Connection supplied at bottom of boiler.
See section 5.
15. Condensate Drain Boiler produces a liquid
(condensate) as a by-product of combustion. (see page
14)
16. Condensate Trap (Field Installed) Condensate must
be piped to appropriate drain. See section 6.
17. Jacket Panel Latch
18. Supply Water Outlet to Heating System (Out)
Connections supplied for connecting from bottom of
boiler. See section 5.
19. Temperature Pressure Gauge (Field Installed)
20. High Voltage Junction Box For connection of 120V
components. See section 8.
21. Flue Collector
22. Vent Temperature Sensor
23. Combustion Analysis Test Port
24. Gas (Control) Valve Delivers proper quantity of fuel
to Combustion Air Blower. See section 7.
25. Combustion Air Blower Delivers proper quantity of
combustion air, receives fuel from gas valve, mixes air
and fuel sending mixture to burner for combustion.
26. Heat Exchanger Surface Temperature Switch
27. Supply Water Temperature Sensor and High Limit
Switch
28. Safety Relief Valve Factory supplied, Field installed.
See section 5.
29. Pump Relay
30. Burner not shown (see page 39)
31. Wall Hanging Support Bracket not shown (see page
12) Integral to boiler. Allows wall mounting when used
with supplied wall mounting bracket. See section 4.
3 - COMPONENT LISTING

8
FIGURE 3-1 Boiler Components (Viewed from Back of Boiler)
(25) VENT CONNECTOR
N O T E :
See Section 5-3
For Safety Relief
Valve Piping
Instructions
(2) COMBUSTION
AIR INLET (23) SAFETY RELIEF VALVE
(27) WALL MOUNT
SUPPORT BRACKET
3 - COMPONENT LISTING
050/075/100/150/200
SIZE SHOWN
GAS CONNECTION
FIGURE 3-2 Jacket Removal (Viewed from Bottom of
Boiler
Jacket Latch - Lift
latch to dis-engage
Bottom of Boiler
FIGURE 3-3 Jacket Removal (Viewed from Left Side
of Boiler
Disengage latch and
lift jacket up and off
jacket support
Jacket Support (Lip)
Jacket Latch

9
3 - COMPONENT LISTING
FIGURE 3-4 Boiler Components 50/75/100 MBH (View from Front of Boiler) As seen on front cover
(2) VENT CONNECTOR
(25) COMBUSTION
AIR
BLOWER
(24) GAS (CONTROL)
VALVE
(28) SAFETY RELIEF
VALVE
(3) COMBUSTION
AIR INLET
N O T E :
See Section 5
For Piping
Instructions
(21) FLUE
COLLECTOR
(14) RETURN WATER
FROM HEATING
SYSTEM (IN)
(18) SUPPLY WATER TO
HEATING SYSTEM (OUT)
(12) LOW VOLTAGE
TERMINAL STRIP
(22) VENT
TEMPERATURE
SENSOR
(1) GAS (CONNECTION)
SHUT OFF VALVE
(23) COMBUSTION
ANALYSIS TEST
PORT
(20) HIGH VOLTAGE
JUNCTION BOX
(10) HEAT
EXCHANGER
(9) BOILER
CONTROL
MODULE
Fuse and
Holder
(4) IGNITER
(5) FLAME
SENSOR
(6) SIGHT GLASS
(7)AIR FLUE
MIXTURE
PRESSURE
TEST PORT
(15) CONDENSATE
DRAIN
(8) USER
INTERFACE
(13) RETURN WATER
TEMPERATURE
SENSOR
(11) ASME
PLATE
(27) SUPPLY WATER
TEMPERATURE SENSOR
& HIGH LIMIT SWITCH
(17) Jacket Latch
(26) HEAT
EXCHANGER SURFACE
TEMPERATURE SWITCH
BRACKET
(19) TEMPERATURE/PRESSURE
GAUGE
(16) CONDENSATE
TRAP
(29) Pump Relay

10
FIGURE 3-5 Boiler Components 150-200 MBH (View from Front of Boiler)
3 - COMPONENT LISTING
(2) VENT CONNECTOR
(24) GAS (CONTROL)
VALVE
(27) SUPPLY
WATER
TEMPERATURE
SENSOR & HIGH
LIMIT SWITCH
(28) SAFETY RELIEF VALVE
(3) COMBUSTION
AIR INLET
N O T E :
See Section 5
For Piping
Instructions
(21) FLUE
COLLECTOR
(14) RETURN WATER
FROM HEATING
SYSTEM (IN)
(18) SUPPLY WATER TO
HEATING SYSTEM (OUT)
(12) LOW VOLTAGE
TERMINAL STRIP
(1) ) GAS (CONNECTION)
SHUT OFF VALVE
(20) HIGH VOLTAGE
JUNCTION BOX
(10) HEAT
EXCHANGER
(9) BOILER CONTROL
MODULE
Fuse and Holder
(5) FLAME SENSOR
(15) CONDENSATE
DRAIN
(8) USER INTERFACE
(25) COMBUSTION
AIR
BLOWER
(26) HEAT
EXCHANGER SURFACE
TEMPERATURE
SWITCH
(6) SIGHT GLASS
(22) VENT TEMPERATURE
SENSOR
(13) RETURN
TEMPERATURE
SENSOR
(4) IGNITER
(23) COMBUSTION
ANALYSIS TEST
PORT
(17) Jacket
Latch
(11) ASME
PLATE
(16) CONDENSATE
TRAP
(19) TEMPERATURE/
PRESSURE GAUGE
(29) PUMP RELAY

11
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, optional oor stand available.
• Determine alternate User Interface mounting location
if desired. See page 81 - Optional User Interface
Relocation.
• 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
050/075/100/
150/200
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
C
B
A
FLOOR
FLOOR
FF
4 - LOCATING BOILER
FRONT OF BOILER
LEFT SIDE
OF BOILER
A
E
E
D
F
F

12
FIGURE 4-2 Wall Mount Bracket Engaged with
Bracket on Boiler (50-100 size shown)
CAUTION
Boiler weight exceeds 75 pounds (34 kg). Do not
lift boiler onto wall without assistance.
!
NOTICE
Lift boiler using chassis. Using front jacket, vent
piping, water or gas ttings to lift boiler may cause
damage to the boiler.
4 - LOCATING BOILER
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 1, page 2.
• 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.
WARNING
Fire, explosion hazard. Mount boiler vertically or
slightly tilted backward to insure proper function of
low water cutoff. Failure to follow these instructions
could result in death or serious injury.
• 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, number 15
and 16.
!
4 Slots for attaching
Wall Mount Bracket
to Studs
Center brackets. Avoid
overhang on sides of
wall mount bracket.

13
5.1 General
• Install piping in accordance with authority having jurisdiction.
NOTICE
Use two (2) wrenches when tightening boiler's
tting and pipes. Boiler's internal piping can be
damaged if subjected to excessive torque.
• 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.
• 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
• 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 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.
5.3 Safety Relief Valve and Air Vent
NOTICE
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.
• Install safety relief valve. See gure 5-1
• Install safety relief valve with spindle in vertical position.
• Do not install shutoff 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.
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.
!
NOTICE
Do not expose boiler and condensate piping to
freezing temperatures.
FIGURE 5-1 Safety Relief Valve (Viewed from rear of
boiler)
Safety Relief
Valve
Position Safety Relief Valve to provide
space for discharge piping.
5 - HYDRONIC PIPING

14
• 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).
5.4 Trim Piping
• Temperature - Pressure Gauge. Install temperature
pressure gauge using adapter, tee and bushing provided
with boiler. See gure 5-3.
• Protect chassis grommets from heat damage.
• Drain Valve. Install drain valve using, tee and adapter
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 5-4, 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 gures 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.
FIGURE 5-3 Temperature Pressure Gauge and Drain
Valve Installations
Temperature Pressure
Gauge shown at
System Supply
Connection
Check Local Codes
For Maximum
Distance To Floor
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
Drain Valve shown
at System Return
Connection to Boiler
Safety Relief Valve
5 - HYDRONIC PIPING

15
Piping Legend
FIGURE 5-4 System Piping
NOTICE
Illustrations are meant to show system piping
concept only. Installer responsible for all
equipment and detailing required by authority
having jurisdiction.
System
Return
System
Supply
Safety Relief Valve
WALL
MOUNTED
ONLY
Pipe to
condensate
drain
Table 3 - System Piping Congurations
Single Boiler
P r i m a r y / S e c o n d a r y
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
P r i m a r y / S e c o n d a r y
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

16
FIGURE 5-5 Single Boiler Primary/Secondary Two-Pipe Zoned System With Zone Valves
FIGURE 5-6 Single Boiler Primary/Secondary Two-Pipe Zoned System With Zone Pumps
DHW
Pump
CH/System
Pump
DHW
Pump
Zone
Pump
5 - HYDRONIC PIPING

17
CH/System
Pump
12"(305mm) Maximum
separation
12"(305mm)
Maximum
separation
Existing closely spaced tees
in primary system loop
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
Existing closely spaced tees
in primary system loop
Limit length
to
5' (1.6m)
12"(305mm)
Maximum
separation
Limit length
to
5' (1.6m)
5 - HYDRONIC PIPING

18
FIGURE 5-8A Multiple Boiler Primary/Secondary Two Pipe Zoned System With Zone Valves - (See Multiple Boiler
Guide)
5 - HYDRONIC PIPING
Up to 16
boilers
DHW
Pump
(See Multiple Boiler Guide)
CH/System
Pump 12"/305mm Maximum Separation
S y s t e m
Temperature
Sensor
Size common piping
per maximum heat
capacity of entire
system
Limit
length to
5' (1.6m)

19
FIGURE 5-8B Multiple Boilers Using Primary/Secondary Pumping with Closed External Primary Loop
5 - HYDRONIC PIPING
Existing closely spaced tees
in primary system loop
12"/305mm
Maximum
Separation
Up to 16
boilers
CH/System
Pump
12"/305mm Maximum Separation
S y s t e m
Temperature
Sensor
Size common piping
per maximum heat
capacity of entire
system
Limit
length to
5' (1.6m)

20
5-8C Multiple Boilers Using Primary/Secondary Pumping with Open External Primary Loop
Existing closely spaced tees
in primary system loop
12"/305mm
Maximum
Separation
CH/System
Pump
12"/305mm Maximum Separation
S y s t e m
Temperature
Sensor
Size common piping
per maximum heat
capacity of entire
system
Limit
length to
5' (1.6m)
5 - HYDRONIC PIPING
Up to 16
boilers