Westinghouse WBMC**500 User manual

Installation
Start-Up
Maintenance
Parts
Warranty
WBMC**500 / WBMC**850 Models*
*“NG” Denotes Natural Gas Operation
“LP” Denotes Propane Gas Operation
“HL” Denotes Installed High and Low Gas Pressure
Switches
This manual must only be used by a qualied installer / service technician. Read all instructions in this manual before
installing. Perform steps in the given order. Failure to do so could result in substantial property damage, severe
personal injury, or death.
Westinghouse reserves the right to make product changes or updates without notice and will not be held liable for
typographical errors in literature.
NOTE TO CONSUMER: PLEASE KEEP ALL INSTRUCTIONS FOR FUTURE REFERENCE.
WHL-033 Rev. 1.29.16
Improper installation, adjustment, alteration, service, or maintenance could void product warranty and cause
property damage, severe personal injury, or death.
This Manual For Use With Boilers Manufactured After
August 13, 2013
Heat Exchanger Bears the ASME “H” Stamp
Commercial
Gas-Fired Boilers

WHL-033 Rev. 1.29.16
2
IF THE INFORMATION IN THIS MANUAL IS NOT FOLLOWED EXACTLY, A FIRE OR EXPLOSION MAY RESULT, CAUSING
PROPERTY DAMAGE, PERSONAL INJURY, OR LOSS OF LIFE. DO NOT STORE GASOLINE OR OTHER FLAMMABLE
VAPORS AND LIQUIDS IN THE VICINITY OF THIS OR ANY OTHER APPLIANCE.
WHAT TO DO IFYOU 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 re department. Installation and service must be provided by a qualied
installer, service agency, or the gas supplier.

WHL-033 Rev. 1.29.16
3
The following dened terms are used throughout this manual
to bring attention to the presence of hazards of various risk
levels or to important product information.
DANGER indicates an imminently hazardous situation
which, if not avoided, will result in serious personal injury or
death.
WARNING indicates a potentially hazardous situation
which, if not avoided, could result in personal injury or death.
CAUTION indicates a potentially hazardous situation which,
if not avoided, may result in moderate or minor personal
injury.
CAUTION used without the safety alert symbol indicates
a potentially hazardous situation which, if not avoided, may
result in property damage.
NOTICE is used to address practices not related to personal
injury.
Foreword
This manual is intended to be used in conjunction with other
literature provided with the boiler. This includes all related
control information. It is important that this manual, all other
documents included in this system, and additional publications
including the Code for the Installation of Heat Producing
Appliances and National Fuel Gas Code - ANSI Z223.1 (latest
versions), be reviewed
in their entirety before
beginning any work.
Installation should be
made in accordance
with the regulations
of the Authority
Having Jurisdiction,
local code authorities,
and utility companies
which pertain to this
type of water heating
equipment.
Authority Having
Jurisdiction (AHJ) – The
AHJ may be a federal,
state, local government,
or individual such as a
re chief, re marshal,
chief of a re prevention
bureau, labor
department or health
department, building
ocial or electrical
inspector, or others
For the Installer
This boiler must be installed by qualied and licensed personnel.
The installer should be guided by the instructions furnished with
the boiler, and by local codes and utility company requirements.
In the absence of local codes, preference should be given to the
National Fuel Gas Code - ANSI Z223.1, latest version.
Installations Must Comply With:
Local, state, provincial, and national codes, laws, regulations,
and ordinances.
The latest version of the National Fuel Gas Code, ANSI Z223.1,
from American Gas Association Laboratories, 8501 East Pleasant
Valley Road, Cleveland, OH 44131.
In Canada - CGA No. B149 (latest version), from Canadian Gas
Association Laboratories, 55 Scarsdale Road, Don Mills, Ontario,
Canada M3B 2R3. Also, Canadian Electrical Code, C 22.1, from
Canadian Standards Association, 5060 Spectrum Way, Suite
100, Mississauga, Ontario, Canada L4W 5N6.
Code for the Installation of Heat Producing Appliances (latest
version) from American Insurance Association, 85 John Street,
New York, NY 11038.
The latest version of the National Electrical Code, NFPA No. 70.
NOTE: The gas manifold and controls met safe lighting and
other performance criteria when undergoing tests specied in
ANSI Z21.13 - latest edition.
having statutory authority. In some circumstances, the property
owner or his/her agent assumes the role, and at government
installations, the commanding ocer or departmental ocial
may be the AHJ.
NOTE: Westinghouse reserves the right to modify product
technical specications and components without prior notice.

WHL-033 Rev. 1.29.16
4
Table of Contents
Part 1 - General Safety Information 5
A. Improper Combustion 6
B. Gas 6
C. When Servicing the Boiler 6
D. Boiler Water 6
E. Freeze Protection 6
Part 2 - Before You Start 6
A. What’s in the Box 6
B. How the Boiler Operates 6
C. Optional Equipment 7
Part 3 - Prepare the Boiler 7
A. Locating the Boiler 8
B. Flooring 9
C. Leveling 9
D. Clearances for Service Access 9
E. Residential Garage Installation 10
F. Exhaust Vent and Intake Pipe 10
1. Direct Vent of Exhaust and Intake 10
2. Indoor Combustion Air in Conned or Unconned Space 10
G. Prevent Combustion Air Contamination 11
H. Removing a Boiler from a Common Vent System 11
I. Water Chemistry Requirements* 12
Part 4 - Piping 14
A. General Plumbing Information 14
B. Relief Valve 14
C. Backow Preventer 14
D. Expansion Tank 14
E. Circulators 15
F. Hydronic Piping with Circulators, Zone Valves, and Multiple
Boilers 15
G. Circulator Sizing 16
H. Check / Control Water Chemistry 17
I. Plumbing 18
J. Fill and Purge Heating System 18
K. Freeze Protection Fluids 18
L. Zoning with Zone Valves 19
M. Zoning with Circulators 19
N. Multiple Boilers 19
O. Applications* 20
The CSD-1 ASME Code, Section CW-400 requires that hot
water heating and supply boilers have a) a UL 353 temperature
control device, b) at least one (1) temperature-actuated control
to shut o the fuel supply when system water reaches a preset
operating temperature, c) a high temperature limit control that
prevents the water temperature from exceeding the maximum
allowable temperature by causing a safety shutdown and
lockout, and d) its own sensing element and operating switch.
The temperature control system integrated into the 926
control provided with this heating appliance complies with
the requirements of CSD-1 Section CW-400 as a temperature
operation control. The control monitors the temperature
dierence between the inlet and the outlet sensor, which is
aected by boiler water ow. If this temperature dierence
exceeds 55°F (typically because of low water ow or very low
heat load), the control will reduce the maximum fan speed.
If the temperature dierence exceeds 60°F, the control will
eectively sense there is little or no water ow or heat load and
shut the boiler down. The controller will restart automatically
once the temperature dierence has dropped below 55°F and
the minimum o time (anti-cycle time) has expired. In addition,
if the control senses that the outlet water temperature has
reached 210°F, the boiler is put into a hard lockout and requires
manual reset to restart.
The hydronic supply and return connections of these
products are for installation in closed loop systems ONLY!
Use of this product in any manner other than described in this
manual may result in premature product failure, substantial
property damage, severe personal injury, or death. Damage or
failure of this product (or the system in which it is installed) due
to unauthorized use IS NOT COVERED BY WARRANTY.
IMPORTANT
In accordance with Section 325 (f) (3) of the Energy Policy
and Conservation Act,Westinghouse has provided this boiler
with multiple features designed to save energy by reducing
the boiler water temperature as heating load decreases.
These features include:
• A modulating combustion system that adjusts ring
rate based on heat demand.
• Adjustment of boiler set point based on inferred heat
load as determined by an outdoor sensor. The outdoor
sensor is supplied by Westinghouse with this boiler.
• This boiler does not include a standing pilot.
• This boiler is designed and shipped to assure the
highest eciency operation possible. Such high
eciency is achieved by limiting heating circuit water
temperature to 140°F when there is no anticipated
heat load, based upon the outdoor sensor and the
Outdoor Reset Curve (sensor response curve) in the
boiler software.
• This feature may be over-ridden as described below in
specic installations:
• The boiler control is equipped with an outdoor sensor
override for use with building management systems
or in cascaded systems (for systems with total input of
300,000 BTU/hr or greater).
See statement below for an important notice on the use of
the override.
IMPORTANT
In accordance with Section 325 (f) (3) of the Energy Policy and
Conservation Act, this boiler is equipped with a feature that
saves energy by reducing the boiler water temperature as
the heating load decreases. This feature is equipped with an
override which is provided primarily to permit the use of an
external energy management system that serves the same
function. THIS OVERRIDE MUST NOT BE USED UNLESS AT
LEAST ONE OF THE FOLLOWING CONDITIONS IS TRUE:
• An external energy management system is installed
that reduces the boiler water temperature as the
heating load decreases.
• This boiler is not used for space heating.
• This boiler is part of a modular or multiple boiler system
having a total input of 300,000 BTU/hr or greater.
• This boiler is equipped with a tankless coil.

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5
Part 5 - Venting and Condensate Removal 22
A. General 22
B. Approved Materials for Exhaust Vent and Intake Pipe 23
C. Additional Requirements for Installation in Canada 23
D. Exhaust Vent and Intake Pipe Location 24
E. Exhaust Vent and Intake Pipe Sizing 25
F. Longer Vent Runs 25
G. Exhaust Vent and Intake Pipe Installation 25
H. Applications 26
1. Direct Vent Installation of Exhaust and Intake 26
2. Room and Indoor Combustion Ventilation Requirements
29
I. Condensate Removal System 30
Part 6 - Wiring 31
A. Installation Must Comply With 31
B. Field Wiring Terminations 31
C. Field Wiring 31
D. Line Voltage Wiring for Standard Boiler 32
E. Alarm Connections 32
F. Low Voltage Connections for Standard Boiler 32
G. Thermostat 32
H. Outdoor Sensor 32
I. Indirect Sensor 32
J. Optional 0-10 Volt Building Control Signal 33
K. Optional High Gas Pressure Switch 33
L. Optional Low Gas Pressure Switch 33
M. Optional Flow Switch 33
N. Optional UL353 Low Water Cut-O Interface Kit 33
O. Wiring of Cascade System Communication Bus 34
P. Cascade Master Pump and Sensor Wiring 34
Q. Cascade Follower Pump and Sensor Wiring 35
Part 7 - Gas Connections 37
A. Gas Piping 37
B. Gas Table 38
C. Check Inlet Gas Pressure 38
D. Boiler Gas Valve 39
Part 8 - Start-Up Preparation 40
A. Check / Control Water Chemistry 40
B. Check for Gas Leaks 40
C. Freeze Protection (When Used) 40
D. Fill and Test Water System 40
E. Purge Air from Water System 41
F. Check Thermostat Circuit(s) 41
G. Condensate Removal 41
H. Final Checks Before Starting Boiler 42
I. Setting Up a Single Boiler 42
J. Setting Up a Cascaded System 42
K. Lockout Condition 42
L. Cascade System Programming 43
Part 9 - Start-Up Procedure 43
A. Control Overview 43
B. Navigation of the Display 43
C. Operating Instructions 44
D. Programming Boiler Settings 44
E. Programming the System Setting 45
F. System Setting Program Navigation 45
G. Resetting the Maintenance Schedule 47
Part 10 - Start-Up Procedures for the Installer 48
A. Boiler Control Status Menu 48
B. Cascade Menu 49
C. Boiler Test Mode 50
Part 11 - Troubleshooting 51
A. Boiler Error and Fault Codes 51
B. Boiler Error 51
C. Boiler Fault 51
D. User Interface Display 52
Part 12 - Maintenance 57
A. Procedures 57
B. Combustion Chamber Coil Cleaning Instructions 57
C. Cleaning Water Side of Heat Exchanger 58
Part 13 - Installation Checklist 63
Part 14 - Maintenance Report 63
Limited Warranty 67
Maintenance Notes 69
Customer Installation Record Form 70
Part 1 - General Safety Information
This boiler is approved for indoor installations only and is not
intended for use as a pool heater. Clearance to combustible
materials: 0” top, bottom, sides, and back. Left side has all
boiler mechanical connections. Boiler must have room for
service: 24” front is minimum recommended service clearance.
(A combustible door or removable panel is acceptable front
clearance.) This boiler has been approved for closet installation
and installation on combustible ooring. Do not install directly on
carpeting. Install the boiler in a location where temperature and
pressure relief valve discharge or a leak will not result in damage
to the surrounding area. If such a location is not available, install
an auxiliary catch pan. Use only Category IV vent systems.
Installer - Read all instructions in this manual before installing.
Perform steps in the given order.
User - This manual is for use only by a qualied heating installer /
service technician. Have this boiler serviced / inspected annually
by a qualied service technician.
FAILURE TO ADHERE TO THE GUIDELINES ON THIS PAGE
CAN RESULT IN SUBSTANTIAL PROPERTY DAMAGE,
SEVERE PERSONAL INJURY, OR DEATH.
NOTE: If the boiler is exposed to the following, do not operate.
Immediately call a qualied service technician.
1. Fire
2. Damage
3. Water
Failure to follow this information could result in property
damage, severe personal injury, or death.
DO NOT USE THIS BOILER IF ANY PART HAS BEEN
SUBMERGED IN WATER. Immediately call a qualied
service technician. The boiler MUST BE replaced if it has been
submerged. Attempting to operate a boiler that has been
submerged could create numerous harmful conditions, such as
a potential gas leakage causing a re and/or explosion, or the
release of mold, bacteria, or other harmful particulates into
the air. Operating a previously submerged boiler could result in
property damage, severe personal injury, or death.
NOTE: Boiler damage due to ood or submersion is considered
an Act of God, and IS NOT covered under product warranty.
Altering any Westinghouse boiler with parts not manufactured
by Westinghouse WILL INSTANTLY VOID the boiler warranty
and could result in property damage, personal injury, or death.

WHL-033 Rev. 1.29.16
6
NOTE: Obey all local codes. Obtain all applicable permits before
installing the boiler.
NOTE: Install all system components and piping in such a
manner that does not reduce the performance of any re rated
assembly.
Do not use this boiler for anything other than its intended
purpose (as described in this manual). Doing so could result in
property damage and WILL VOID product warranty.
High heat sources (sources generating heat 100oF / 37oC or
greater, such as stove pipes, space heaters, etc.) may damage
plastic components of the boiler as well as plastic vent pipe
materials. Such damages ARE NOT covered by warranty. It is
recommended to keep a minimum clearance of 8” from high
heat sources. Observe heat source manufacturer instructions,
as well as local, state, provincial, and national codes, laws,
regulations and ordinances when installing this boiler and
related components near high heat sources.
A. Improper Combustion
Do not obstruct the ow of combustion and ventilating air.
Adequate air is necessary for safe operation. Failure to keep the
exhaust vent and combustion air intake clear of ice, snow, or
other debris could result in property damage, serious personal
injury, or death.
B. Gas
Should overheating or gas supply fail to shut o, turn o the
manual gas control valve to the boiler.
C. When Servicing the Boiler
To avoid electric shock, disconnect electrical supply before
performing maintenance.
NOTE: When inquiring about service or troubleshooting,
reference the model and serial numbers from the boiler rating
label.
To avoid severe burns, allow boiler and associated equipment to
cool before servicing.
Be sure to disconnect electrical power before opening boiler
cabinet or performing service. Failure to do so could result in
electrical shock, property damage, serious personal injury, or
death.
Due to low water content of the boiler, improperly sizing
the boiler in regard to potable water heating load will result
in excessive boiler cycling and accelerated component
failure. Westinghouse DOES NOT warrant failures caused by
improperly sized boiler applications. DO NOT oversize the
boiler to the system. Modular boiler installations greatly reduce
the likelihood of boiler oversizing.
D. Boiler Water
• If you have an old system with cast iron radiators,
thoroughly ush the system (without boiler connected)
to remove sediment. The high-eciency heat exchanger
can be damaged by build-up or corrosion due to
sediment. Westinghouse recommends a suction
strainer in this type of system.
• Do not use petroleum-based cleaning or sealing
compounds in boiler system. Gaskets and seals in
the system may be damaged, possibly resulting in
substantial property damage.
• Do not use “homemade cures” or “boiler patent
medicines”. Substantial property damage, damage to
boiler, and/or serious personal injury may result.
• Continual fresh make-up water will reduce boiler life.
Mineral buildup in the heat exchanger reduces heat
transfer, overheats the stainless steel heat exchanger,
and causes failure. Addition of oxygen from make-
up water can cause internal corrosion in system
components. Leaks in the boiler or piping must be
repaired at once.
NOTE: DO NOT add cold make up water to the system when
the boiler is hot. Thermal shock can potentially cause cracks
in the heat exchanger. Such damage IS NOT covered by
warranty.
NEVER use any toxic chemical, including automotive,
standard glycol antifreeze, or ethylene glycol made for
hydronic (non-potable) systems. These chemicals can
attack gaskets and seals in water systems, are poisonous if
consumed, and can cause personal injury or death.
UNCRATING THE BOILER - Any claims for damage or
shortage in shipment must be led immediately against the
transportation company by the consignee.
Part 2 - Before You Start
Failure of the boiler due to freeze related damage IS NOT
covered by product warranty.
E. Freeze Protection
NOTE: Consider piping and installation when determining
boiler location.
Remove all sides of the shipping crate of the boiler.
Components included with the boiler:
• Temperature and Pressure Gauge
• Outdoor Sensor
• Three (3) Stainless Steel Screens
• Installation Manual and Warranty
• User’s Information Manual
• CSD-1 Form
• H-3 Data Sheet
A. What’s in the Box
B. How the Boiler Operates
Condensing technology intelligently delivers highly ecient
hydronic heating while maximizing eciency by measuring
data from the heating system. Outlined below are the features
of the system and how they operate:

WHL-033 Rev. 1.29.16
7
Stainless Steel Heat Exchanger
The highly ecient stainless steel heat exchanger is designed
to use the cold water return from the system and extract the
last bit of heat before it is exhausted.
Modulating Combustion System
The combustion system modulates the output of the burner
during operation to match system demand and achieve
the control set point while in operation. The set point can
change by internal or external signals to enhance the overall
performance of the system.
Control
The integrated control system monitors the system and
regulates fan speed to control boiler output. This allows the
boiler to deliver only the amount of heat energy required
and nothing more. The system can be further enhanced by
installing an indirect water heater to provide domestic hot
water.
The control can regulate the output of multiple boilers
through its cascade system function. The cascade system is
capable of connecting up to eight boilers together in such a
way that they function as one boiler system. This allows for
greater turn down ratios and provides systematic control of
the multiple boilers in an installation to minimize downtime
and maximize eciency.
The cascade system works by establishing one boiler as the
master and the other connected boilers as followers. The
master boiler requires a sensor to provide feedback on set
point temperature in order to adjust heating input from the
connected boilers. Each cascaded boiler will have its own
pump to provide maximum ow and control heat exchanger
ow rate.
NOTE: When using a system sensor, pipe insulation must be
wrapped around it to improve temperature measurement
accuracy and increase system eciency.
Text Display and Operational LED Light Indicators
The display allows the user to change system parameters and
monitor system outputs.
Gas Valve
Senses suction from the blower, allowing gas to ow only if
powered and combustion air is owing.
Integrated Venturi (500 Models) or Swirl Plate (850 Models)
Controls air and gas ow into the burner.
Burner
The high grade stainless steel burner uses premixed air and
gas to provide a wide range of ring rates.
Spark Ignition
The burner is ignited by applying high voltage through the
system spark electrode. The spark from the electrode ignites
mixed gas o of the burner.
Supply Water Temperature Sensor
This sensor monitors the boiler outlet water temperature
(System Supply). The control adjusts boiler ring rate so the
supply temperature will match the boiler set point.
Return Water Temperature Sensor
This sensor monitors boiler return water temperature (System
Return).
Temperature and Pressure Gauge
Allows the user to monitor system temperature and pressure.
Electrical eld connections with terminal strips
The electrical cover allows easy access to the clearly marked
line voltage and low voltage terminal strips to facilitate wiring
the boiler.
Condensate Collection System
This boiler is a high eciency appliance and will produce
condensate. The condensate collection system has a oat switch
which monitors condensate level and prevents condensate from
backing up into the combustion system. Inside the collection
system is a built in trap which seals the combustion system from
the connected drain. This condensate should be neutralized to
avoid damage to the drainage system or piping.
Flow Protection
The optional ow switch is designed to protect the boiler
during low ow conditions. The boiler control also monitors
ow through the heat exchanger by monitoring the return and
supply sensors and will shut down the burner before overheating
occurs.
Outdoor Sensor
The control adjusts unit set point based on the outdoor
temperature measured by this sensor to provide greater
eciency.
System Sensor (Optional)
This sensor is designed to be used in a cascade system. The
system pipe sensor measures the temperature of return water
and communicates with the control system to modulate the
ring rate of the connected boilers.
NOTE: When using a system sensor, pipe insulation must be
wrapped around it to improve temperature measurement
accuracy and increase overall system eciency.
0-10 Volt Input
Allows the installer to connect a BMS (Building Management
System) to control the boiler.
Indirect Tank Sensor (optional)
Monitors storage tank temperature.
C. Optional Equipment
Optional equipment available from Westinghouse (and Part #):
• System Sensor (7250P-324)
• Indirect Tank Sensor (7250P-325)
• 4” Stainless Steel Vent Termination Kit (V2000)
• 6” Stainless Steel Vent Termination Kit (V3000)
• High and Low Gas Pressure Switch Kit with Manual Reset
(7350P-600)
• UL 353 Compliant Low Water Cut-O Interface Kit with
Manual Reset (7350P-601)
• Alarm System (to monitor any failure) (7350P-602)
• PC Connection Kit (7250P-320)
• Condensate Neutralizer (7350P-611)
• Caster Kit (7350p-604)
• Stacking Kit (7350P-603)
• Flow Switch Kit (7350P-605)
Part 3 - Prepare the Boiler
Remove all sides of the shipping crate to allow the boiler to
be moved into its installation location. Pick the boiler up by
the lifting rings to avoid damage to the boiler enclosure. Use
either solid 3/4” diameter black iron pipe or lifting straps to lift
the boiler o its shipping crate. The boiler is heavy. At least two
individuals are needed to properly handle the boiler. The boiler
is also equipped with leveling feet that can be used to level the
boiler properly on an uneven location surface. If surface ooring

WHL-033 Rev. 1.29.16
8
Figure 1 - Lifting the Boiler
COLDWEATHER HANDLING - If the boiler has been stored in a
very cold location (BELOW 0oF) before installation, handle with
care until the components come to room temperature. Failure
to do so could result in damage to the boiler.
Carefully consider installation when determining boiler location.
Please read the entire manual before attempting installation.
Failure to properly take factors such as boiler venting, piping,
condensate removal, and wiring into account before installation
could result in wasted time, money, and possible property
damage and personal injury.
This boiler is certied for indoor use only. DO NOT INSTALL
OUTDOORS. Outdoor installations ARE NOT covered by
warranty. Failure to install the boiler indoors could result in
property damage, severe personal injury, or death.
A. Locating the Boiler
is rough, take care when moving the boiler into position, as
catching the leveling feet could damage the boiler.
Incorrect ambient conditions can lead to damage to the
heating system and put safe operation at risk. Ensure that the
installation location adheres to the information included in this
manual. Failure to do so could result in property damage, serious
personal injury, or death. Failure of boiler or components due
to incorrect operating conditions IS NOT covered by product
warranty.
1. Installation Area (Mechanical Room) Operating Conditions
• Ensure ambient temperatures are higher than 32oF / 0oC
and lower than 104oF / 40oC
• Prevent the air from becoming contaminated by the
products, places, and conditions listed in this manual
• Avoid continuously high levels of humidity
• Never close existing ventilation openings
• Ensure a minimum 1” clearance around hot water and
exhaust vent pipes
• NOTE: To prevent condensing in the fan, it is
recommended to avoid prolonged exposure to
temperatures below 45oF
This boiler has a condensate disposal system that may
freeze if exposed to sustained temperatures below 32oF.
Precautions should be taken to protect the condensate trap
and drain lines from sustained freezing conditions. Failure
to take precautions could result in property damage, severe
personal injury, or death.
2. Check for nearby connections to:
• System water piping
• Venting connections
• Gas supply piping
• Electrical power
• Condensate drain
3. Check area around boiler. Remove any combustible
materials, gasoline, and other ammable liquids.
Failure to keep the boiler area clear and free of combustible
materials, liquids, and vapors can result in substantial
property damage, severe personal injury, or death.
Locate the boiler where any leakage from the relief valve,
related piping, tank, or connections will not result in damage
to surrounding areas or lower oors of the building. The boiler
should be located near a oor drain or installed in a drain pan.
Leakage damages ARE NOT covered by warranty.
The service life of the boiler’s exposed metallic surfaces, such
as the casing, as well as internal surfaces, such as the heat
exchanger, are directly inuenced by proximity to damp and
salty marine environments. In such areas higher concentration
levels of chlorides from sea spray coupled with relative
humidity can lead to degradation of boiler components.
In these environments, boilers must not be installed using
direct vent systems which draw outdoor air for combustion.
Such boilers must be installed using room air for combustion.
Indoor air will have a much lower relative humidity, and hence
potential corrosion will be minimized.

WHL-033 Rev. 1.29.16
9
High heat sources (generating heat 100oF / 37oC or greater,
such as boiler ue pipes, space heaters, etc.) may damage
plastic components of the boiler as well as plastic vent pipe
materials. Such damages ARE NOT covered by warranty. It is
recommended to keep a minimum clearance of 8” from high
heat sources. Observe heat source manufacturer instructions,
as well as local, state, provincial, and national codes, laws,
regulations, and ordinances when installing this boiler and
related components near high heat sources.
Failure of the boiler or components due to incorrect operating
conditions IS NOT covered by product warranty.
4. Gas control system components must be protected from
dripping water during operation and service.
5. If the boiler is to replace an existing boiler, check for and
correct any existing system problems, such as:
• System leaks
• Location that could cause the system and boiler to
freeze and leak
• Incorrectly sized expansion tank
6. Clean and ush system when reinstalling a boiler.
NOTE: When installing in a zero clearance location, it may
not be possible to read or view some product labeling. It is
recommended to make note of the boiler model and serial
number.
Use extreme care not to drop the boiler or cause bodily injury
while lifting the boiler.
Gas conversion should be performed BEFORE the boiler is
installed. Carefully follow the gas conversion instructions
when performing the conversion.
Failure to follow these instructions could result in property
damage, severe personal injury, or death.
This boiler is approved for installation on combustible
ooring, but must never be installed on carpeting. Installing
this boiler on carpeting could result in re, property damage,
severe personal injury, or death.
B. Flooring
Assure that the oor and structure of the installation location
are sucient to support the full installed weight of the
boiler, including water content of the heat exchanger and
related piping. Failure to ensure the oor and structure of the
installation location are structurally sound before installation
of the boiler can result in structural failure, substantial
property damage, severe personal injury, or death.
C. Leveling
In order for the condensate to properly ow out of the
collection system, the area where you locate the boiler must
be level. Location must also fully support the weight of the
lled boiler.
Figure 2 - Correct and Incorrect Leveling
D. Clearances for Service Access
NOTE: If you do not provide the minimum clearances shown in
Figure 3 it might not be possible to service the boiler without
removing it from the space.
NOTE: A combustible door or removable panel is acceptable
front clearance.
The space must be provided with combustion / ventilation air
openings correctly sized for all other appliances located in the
same space as the boiler. The boiler cover must be securely
fastened to prevent the boiler from drawing air from the boiler
room. This is particularly important if the boiler is in a room with
other appliances. Failure to comply with the above warnings
could result in substantial property damage, severe personal
injury, or death.
All boilers eventually leak. It is recommended to install a catch
pan beneath the boiler. This catch pan should be sized with a
maximum depth of 2”, and a minimum diameter 2” greater than
the diameter of the boiler. The catch pan should empty into
an open drain line. This drain line should be 3/4” ID minimum,
piped to an open drain. Failure to follow these instructions could
result in property damage. Such damages ARE NOT covered by
product warranty.
This boiler must be installed upright in the vertical position as
described in this manual. DO NOT attempt to install this boiler
in any other orientation. Doing so will result in improper boiler
operation and property damage, and could result in serious
personal injury or death.

WHL-033 Rev. 1.29.16
10
E. Residential Garage Installation
Precautions
If the boiler is located in a residential garage, per ANSI Z223.1:
• Install the boiler burner and ignition devices a minimum
of 18” above the oor of the garage. This will ensure the
burner and ignition devices are well o the oor.
• When raising the boiler ensure the entire bottom and
fully lled weight of the boiler are fully supported.
• Locate or protect the boiler so it cannot be damaged by
a moving vehicle.
Figure 3 - Recommended Service Clearances
Check with your AHJ for requirements when installing the
boiler in a garage. Failure to properly take factors such as boiler
venting, piping, condensate removal, and wiring into account
before installation could result in wasted time, money, and
possible property damage, personal injury, or death.
F. Exhaust Vent and Intake Pipe
The boiler is rated ANSI Z21.13 Category IV (pressurized vent,
likely to form condensate in the vent) and requires a special vent
system designed for pressurized venting.
NOTE: The venting options described here (and further
detailed in the Venting section, this manual) are the lone
venting options approved for this boiler. Failure to vent the
boiler in accordance with the provided venting instructions
will void the warranty.
Failure to vent the boiler properly will result in serious personal
injury or death.
Do not attempt to vent this boiler by any means other than
those described in this manual. Doing so will void the warranty
and may result in severe personal injury or death.
The exhaust discharged by this boiler may be very hot. Avoid
touching or other direct contact with the exhaust gases of the
vent termination assembly. Doing so could result in severe
personal injury or death.
Vents must be properly supported. Boiler exhaust and intake
connections are not designed to carry heavy weight. Vent
support brackets must be within 1’ of the boiler and the
balance at 4’ intervals. Boiler must be readily accessible for
visual inspection for rst 3’ from the boiler. Failure to properly
support vents could result in property damage, severe
personal injury, or death.
1. Direct Vent of Exhaust and Intake
If installing a direct vent option, combustion air must be
drawn from the outdoors directly into the boiler intake and
exhaust must terminate outdoors. There are three basic direct
vent options detailed in this manual: 1. Side Wall Venting, 2.
Roof Venting, and 3. Unbalanced Venting.
Be sure to locate the boiler such that the exhaust vent and
intake piping can be routed through the building and properly
terminated. Dierent vent terminals can be used to simplify
and eliminate multiple penetrations in the building structure
(see Optional Equipment in Venting Section). The exhaust
vent and intake piping lengths, routing, and termination
methods must all comply with the methods and limits given
in the Venting Section, this manual.
When installing a combustion air intake from outdoors, care
must be taken to utilize uncontaminated combustion air. To
prevent combustion air contamination, see Table 1.
2. Indoor Combustion Air in Conned or Unconned Space
This boiler requires fresh, uncontaminated air for safe
operation and must be installed in a mechanical room where
there is adequate combustion and ventilating air. NOTE: To
prevent combustion air contamination, see Table 1.
Combustion air from the indoor space can be used if the space
has adequate area or when air is provided through a duct
or louver to supply sucient combustion air based on the
boiler input. Never obstruct the supply of combustion air to
the boiler. If the boiler is installed in areas where indoor air
is contaminated (see Table 1) it is imperative that the boiler
be installed as direct vent so that all combustion air is taken
directly from the outdoors into the boiler intake connection.
Unconned space is space with volume greater than 50

WHL-033 Rev. 1.29.16
11
cubic feet per 1,000 BTU/hr (4.8 cubic meters per kW) of the
total input rating of all fuel-burning appliances installed in
that space. Rooms connected directly to this space through
openings not furnished with doors are considered part of the
space. See Venting Section for details.
Conned space is space with volume less than 50 cubic feet
per 1,000 BTU/hr (4.8 cubic meters per kW) of the total input
rating of all fuel-burning appliances installed in that space.
Rooms connected directly to this space through openings not
furnished with doors are considered part of the space.
When drawing combustion air from inside a conventionally
constructed building to a conned space, such space should
be provided with two permanent openings: one located 6”
(15 cm) below the space ceiling, the other 6” (15cm) above
the space oor. Each opening should have a free area of one
square inch per 1,000 BTU/hr (22cm2/kW) of the total input of
all appliances in the space, but not less than 100 square inches
(645cm2).
If the conned space is within a building of tight construction,
air for combustion must be obtained from the outdoors as
outlined in the Venting section of this manual.
When drawing combustion air from the outside into the
mechanical room, care must be taken to provide adequate
freeze protection.
Failure to provide an adequate supply of fresh combustion
air can cause poisonous ue gases to enter the living space,
resulting in severe personal injury or death. To prevent
combustion air contamination, see Table 1.
G. Prevent Combustion Air Contamination
Install intake air piping for the boiler as described in the
Venting Section, this manual. Do not terminate exhaust in
locations that can allow contamination of intake air.
Ensure that the intake air will not contain any of the
contaminants in Table 1. Contaminated air will damage the
boiler, resulting in possible substantial property damage,
severe personal injury, or death. For example, do not pipe
intake air near a swimming pool or laundry facilities. These
areas always contain contaminants.
Products to Avoid Areas Likely to Have
Contaminants
Spray cans containing
uorocarbons
Dry cleaning / laundry areas and
establishments
Permanent wave solutions Swimming pools
Chlorinated waxes / cleaners Metal fabrication plants
Chlorine-based swimming pool
chemicals Beauty shops
Calcium chloride used for thawing Refrigeration repair shops
Sodium chloride used for water
softening Photo processing plants
Refrigerant leaks Auto body shops
Paint or varnish removers Plastic manufacturing plants
Hydrochloric or Muriatic acid Furniture renishing areas and
establishments
Cements and glues New building construction
Antistatic fabric softeners used in
clothes dryers Remodeling areas
Chlorine-type bleaches, laundry
detergents, and cleaning solvents Garages and workshops
Adhesives used to fasten building
products
Table 1 - Products and Areas Likely to Have Contaminants
NOTE: DAMAGE TO THE BOILER CAUSED BY EXPOSURE
TO CORROSIVE VAPORS IS NOT COVERED BY WARRANTY.
(Refer to the limited warranty for complete terms and
conditions.)
H. Removing a Boiler from a Common Vent System
Failure to follow all instructions can result in ue gas spillage
and carbon monoxide emissions, causing severe personal injury
or death.
Do not install the boiler into a common vent with any other
appliance. This will cause ue gas spillage or appliance
malfunction, resulting in possible substantial property damage,
severe personal injury, or death.
When removing an existing boiler, follow the steps below.
1. Seal any unused openings in the common venting system.
2. Visually inspect the venting system for proper size and
horizontal pitch to determine if there is blockage, leakage,
corrosion, or other deciencies that could cause an unsafe
condition.
3. If practical, close all building doors, windows, and doors
between the space in which the boiler remains connected to
the common venting system and other spaces in the building.
Turn on clothes dryers and any appliances not connected to
the common venting system. Turn on any exhaust fans, such as
range hoods and bathroom exhausts, at maximum speed. Do
not operate a summer exhaust fan. Close all replace dampers.
4. Place in operation the appliance being inspected. Follow the
lighting instructions. Adjust the thermostat so the appliance will
operate continuously.
5. Test for spillage at the draft hood relief opening after 5
minutes of main burner operation. Use the ame of a match or

WHL-033 Rev. 1.29.16
12
candle or smoke from a cigarette.
6. After it has been determined that each appliance remaining
connected to the common venting system properly vents
when tested as outlined, return doors, windows, exhaust fans,
replace dampers, and any other gas burning appliances to their
previous condition of use.
7. Any improper operation of the common venting system
should be corrected to conform to the National Fuel Gas Code,
ANSI Z223.1. When resizing any portion of the common venting
system, the system should approach the minimum size as
determined using the appropriate tables in Appendix G of ANSI
Z223.1.
Figure 4 - CO Warning Label
I. Water Chemistry Requirements*
Chemical imbalance of the water supply may aect eciency
and cause severe damage to the boiler and associated
equipment. Westinghouse recommends having water quality
professionally analyzed to determine whether it is necessary to
install a water softener. It is important that the water chemistry
on both the domestic hot water and central heating sides are
checked before installing the boiler, as water quality will aect
the reliability of the system. In addition, operating temperatures
above 140oF will cause the boiler to operate continuously,
accelerating the build-up of lime scale and possibly shortening
the service life of the boiler. Failure of a boiler due to lime scale
build-up, low pH, or other chemical imbalance IS NOT covered
by the warranty.
• Sodium less than 20 mGL
• Water pH between 6.0 and 8.0
• Maintain water pH between 6.0 and 8.0. Check with
litmus paper or have it chemically analyzed by water
treatment company.
• If the pH diers from above, consult local water
treatment for treatment needed.
• Hardness less than 7 grains
• Consult local water treatment companies for unusually
hard water areas (above 7 grains hardness).
• Chlorine concentration less than 100 ppm
• Using chlorinated fresh water should be acceptable
as levels are typically less than 5 ppm.
• Do not connect the boiler to directly heat swimming
pool or spa water.
• Do not ll boiler or operate with water containing
chlorine in excess of 100 ppm.
*NOTE: It is recommended to clean the heat exchanger at
least once a year to prevent lime scale buildup. To clean the
heat exchanger, follow the maintenance procedure in this
manual.
Hardness: Less than 7 grains
Chloride levels: Less than 100 ppm
pH levels: 6 - 8
TDS: Less than 2000 ppm
Sodium: Less than 20 mGL

WHL-033 Rev. 1.29.16
13
Figure 5 - Boiler Dimensions - NOTE: All Dimensions Are Approximate - VWH in Model Number Denotes Volume Water Heater Model

WHL-033 Rev. 1.29.16
14
Part 4 - Piping
Failure to follow the instructions in this section WILL VOID the
warranty and may result in property damage, severe personal
injury, or death.
Dielectric unions or galvanized steel ttings must not be used
in a system with this boiler. Doing so WILL VOID the warranty.
Use only copper, brass, or stainless steel ttings. Teon thread
sealant must be used on all connections.
DO NOT pipe this boiler with black iron, galvanized steel, steel,
or lead pipe. Doing so will result in premature product failure
and property damage, and WILL VOID the warranty.
A. General Plumbing Information
Use two wrenches when tightening water piping at boiler. Use
one wrench to prevent the boiler return or supply line from
turning. Failure to prevent piping connections from turning
could cause damage to boiler components.
The building piping system must meet or exceed the the piping
requirements in this manual.
NOTE: The addition of a high temperature limiting device is
important if the boiler is to be connected to a domestic hot
water system.
Plumbing of this product should only be done by a qualied,
licensed plumber in accordance with all local plumbing codes.
The boiler may be connected to an indirect water heater to
supply domestic hot water. Westinghouse oers indirect water
heaters in either stainless steel or glass-lined construction.
The control module uses temperature sensors to provide both
high limit protection and modulating temperature control. The
control module also provides low water protection by sensing
the water level in the heat exchanger. Some codes/jurisdictions
may require additional external controls..
B. Relief Valve
To avoid water damage or scalding due to relief valve operation:
• Discharge line must be connected to relief valve outlet
and run to a safe place of disposal. Terminate the
discharge line in a manner that will prevent possibility of
severe burns or property damage should the relief valve
discharge.
• Discharge line must be as short as possible and the same
size as the valve discharge connection throughout its
entire length.
• Discharge line must pitch downward from the valve
and terminate at least 6” above the oor drain, making
discharge clearly visible.
• The discharge line shall terminate plain, not threaded,
with a material serviceable for temperatures of 375oF or
greater.
• Do not pipe discharge to any location where freezing
Connect discharge piping to a safe disposal location by following
these guidelines.
RE-INSPECTION OF T&P RELIEF VALVES: T&P valves
should be inspected AT LEAST ONCE EVERY THREE
YEARS, and replaced if necessary, by a licensed plumbing
contractor or qualied service technician to ensure that the
product has not been aected by corrosive water conditions
and to ensure that the valve and discharge line have not been
altered or tampered with illegally. Certain naturally occuring
conditions may corrode the valve and its components over
time, rendering the valve inoperative. Such conditions can
only be detected if the valve and its components are physically
removed and inspected. Do not attempt to conduct an
inspection on your own. Contact your plumbing contractor
for a re-inspection to assure continued safety.
Do not thread a cap or plug into the relief valve or relief
valve line under any circumstances! Explosion and property
damage, serious injury, or death may result.
FAILURE TO RE-INSPECT THE T&P VALVE AS DIRECTED
COULD RESULT IN UNSAFE TEMPERATURE AND/OR
PRESSURE BUILD-UP WHICH CAN RESULT IN PROPERTY
DAMAGE, SERIOUS PERSONAL INJURY, OR DEATH.
could occur.
• No valve may be installed between the relief valve and
boiler or in the discharge line. Do not plug or place any
obstruction in the discharge line.
• Test the operation of the relief valve after lling and
pressurizing the system by lifting the lever. Make sure
the valve discharges freely. If the valve fails to operate
correctly, immediately replace with a new properly
rated relief valve.
• Test T&P valve at least once annually to ensure the
waterway is clear. If valve does not operate, turn the
boiler “o” and call a plumber immediately.
• Take care whenever operating relief valve to avoid
scalding injury or property damage.
FAILURE TO COMPLY WITH THE ABOVE GUIDELINES
COULD RESULT IN FAILURE OF RELIEF VALVE OPERATION,
RESULTING IN POSSIBILITY OF SUBSTANTIAL PROPERTY
DAMAGE, SEVERE PERSONAL INJURY, OR DEATH.
C. Backow Preventer
Use a backow preventer specically designed for hydronic
boiler installations. This valve should be installed on the cold
water ll supply line per local codes.
All piping methods in this manual use primary / secondary
connections to the boiler loop. This is to avoid the possibility
of inadequate ow through the boiler. For other piping
methods, consult your local Westinghouse representative or
refer to Applications in this manual.
D. Expansion Tank
Expansion Tank and Make-Up Water
1. Ensure that the expansion tank is sized to correctly handle
boiler and system water volume and temperature.

WHL-033 Rev. 1.29.16
15
Undersized expansion tanks cause system water to be lost
from the relief valve, causing make-up water to be added.
Eventual boiler failure can result due to excessive make-
up water addition. SUCH FAILURE IS NOT COVERED BY
WARRANTY.
2. The expansion tank must be located as shown in
Applications, this manual, or following recognized design
methods. See expansion tank manufacturer’s instructions for
details. Always install an expansion tank designed for potable
water systems.
3. Connect the expansion tank to the air separator only if the
separator is on the suction side of the circulator. Always install
the system ll connection at the same point as the expansion
tank connection to the system.
4. Most chilled water systems are piped using a closed type
expansion tank.
Diaphragm (or Bladder) ExpansionTank
Always install an automatic air vent on top of the air separator
to remove residual air from the system.
Expansion tanks must be sized according to total system
volume. This includes all length of pipe, all xtures, boilers,
etc. Failure to properly size for system expansion could result
in wasted time, money, possible property damage, serious
injury, or death.
Expansion Tank Sizing*
Model Heat Exchanger Volume (Gallons)
500 4.2
850 5.8
Table 2 - *Add Required Storage Tank Gallon Size to Heat
Exchanger Volume - 119 and 175 Gallon Tanks Available
DO NOT install automatic air vents on closed type expansion
tank systems. Air must remain in the system and return to the
tank to provide an air cushion. An automatic air vent would
cause air to leave the system, resulting in improper operation
of the expansion tank.
E. Circulators
SIZING SPACE HEAT SYSTEM PIPING
1. In all diagrams, the space heating system is isolated from
the boiler loop by the primary/secondary connection.
2. Size the piping and components in the space heating system
using recognized design methods.
DO NOT use the boiler circulator in any location other than
the ones shown in this manual. The boiler circulator location
is selected to ensure adequate ow through the boiler.
Failure to comply with this caution could result in unreliable
performance and nuisance shutdowns from insucient ow.
F. Hydronic Piping with Circulators, Zone Valves, and
Multiple Boilers
The boiler is designed to function in a closed loop hydronic
system. The included temperature and pressure gauge allows
the user to monitor system pressure and outlet temperature
from the boiler. It is important to note that the boiler has a
minimal amount of pressure drop that must be calculated
when sizing the circulators. Each boiler installation must have
an air elimination device that will remove air from the system.
Install the boiler so the gas ignition system components
are protected from water (dripping, spraying, etc.). Allow
clearance for basic service of the boiler circulator, valves, and
other components. Observe minimum 1” clearance around all
uninsulated hot water pipes when openings around pipes are
not protected by non-combustible materials.
On a boiler installed above radiation level, some states and
local codes require a low water cut o device. This is provided
standard on the boiler. Check with local codes for additional
requirements. If the boiler supplies hot water to heating coils in
air handler units, ow control valves or other devices must be
installed to prevent gravity circulation of boiler water in the coils
during the cooling cycle. Chilled water medium must be piped in
parallel with the boiler.
Freeze protection for new or existing systems must use glycol
specically formulated for this purpose. This glycol must include
inhibitors that will prevent it from attacking metallic system
components. Make certain that the system uid is checked for
the correct glycol concentration and inhibitor level. The system
should be tested at least once a year and as recommended by
the producer of the glycol solution. Allowance should be made
for the expansion of the glycol solution in the system piping.
Example: 50% by volume glycol solution expands 4.8% in
volume for the temperature increase from 32oF to 180oF, while
water expands 3% over the same temperature rise.
Never use dielectric unions or galvanized steel ttings when
connecting to a stainless steel storage tank or boiler. Failure to
follow this instruction can lead to premature failure of the boiler
system. Such failures ARE NOT covered by warranty.
The boiler should not be operated as a potable hot water heater.
The boiler should not be used as a direct hot water heating
device.

WHL-033 Rev. 1.29.16
16
Minimum Boiler Flow Rates
Model Minimum Flow (GPM)
500 33
850 54
Table 3 - Minimum Flow Rates
Table 4 - Heat Exchanger Pressure Drop
The chart below represents various system design temperature rise through the boiler along with respective ows and friction
loss. This is provided to aid in circulator selection.
System Temperature Rise Chart
20°Δt 25°Δt 30°Δt
Model Friction Ft Flow Rate (GPM) Friction Ft Flow Rate (GPM) Friction Ft Flow Rate (GPM)
500 19’ 50 11’ 40 8’ 33
850 35’ 85 26’ 65 18’ 54
Table 5 - Temperature Rise, Friction Ft and Flow Rate
In addition, the boiler heat exchanger has a minimum total water volume that must be taken into account when sizing the
circulator. Minimum boiler ow rates are listed in the table below.
The boiler heat exchanger does have a pressure drop which must be considered in system design. Refer to the graph in Table 4
for pressure drop through the boiler heat exchanger.
G. Circulator Sizing

WHL-033 Rev. 1.29.16
17
Table 6 - Multiple Boiler Manifold Piping
The chart below represents the combined ow rates and pipe sizes when using multiple boilers to design the manifold system for
the primary circuit. To size, simply add up the number of boilers and the required ow rates for the system design temperature.
Example: (5) 500 boilers with a design of 30oF temperature rise with each boiler having an individual ow rate of 33 GPM. To
correctly size the manifold feeding these boilers, you would need a pipe size of 4”.
NOTE: Boiler failure due to improper water chemistry is not
covered by warranty.
Water Chemistry*
• Sodium less than 20 mGL
• Water pH between 6.0 and 8.0
• Maintain water pH between 6.0 and 8.0. Check with
litmus paper or have it chemically analyzed by water
treatment company.
• If the pH diers from above, consult local water
treatment for treatment needed.
• Hardness less than 7 grains
• Consult local water treatment companies for
unusually hard water areas (above 7 grains hardness).
• Chlorine concentration less than 100 ppm
• Using chlorinated fresh water should be acceptable
as levels are typically less than 5 ppm.
• Do not connect the boiler to directly heat swimming
pool or spa water.
• Do not ll boiler or operate with water containing
chlorine in excess of 100 ppm.
*NOTE: It is recommended to clean the heat exchanger at
least once a year to prevent lime scale buildup. To clean the
heat exchanger, follow the maintenance procedure in this
manual.
H. Check / Control Water Chemistry Hardness: Less than 7 grains
Chloride levels: Less than 100 ppm
pH levels: 6 - 8
TDS: Less than 2000 ppm
Sodium: Less than 20 mGL
Clean system to remove sediment*
1. You must thoroughly ush the system (without boiler
connected) to remove sediment. The high-eciency heat
exchanger can be damaged by buildup or corrosion due to
sediment.
2. For zoned systems, ush each zone separately through a
purge valve. (If purge valves and isolation valves are not already
installed, install them to properly clean the system.)
3. Flush system until water runs clean and you are sure piping is
free of sediment.
*NOTE: It is recommended you clean heat exchanger at
least once a year to prevent lime scale buildup. Follow the
maintenance procedure to clean the heat exchanger in the
Maintenance Section of this manual.
Test/replace freeze protection uid
1. For systems using freeze protection uids, follow uid
manufacturer’s instructions to verify inhibitor level and that
other uid characteristics are satisfactory.
2. Freeze protection uid must be replaced periodically due to
degradation of inhibitors over time. Follow all uid manufacturer
instructions.

WHL-033 Rev. 1.29.16
18
J. Fill and Purge Heating System
• Attach the hose to balance and purge hose connector
or drain valve and run hose to nearest drain.
• Close the other side of the balance and purge valve or
the shut o valve after the drain.
• Open rst zone balance and purge or drain valve to let
water ow out the hose. If zone valves are used, open
the valves one at a time manually. (NOTE: You should
check the valve manufacturer’s instructions prior to
opening valves manually, so as not to damage the
valves.)
• Manually operate ll valve regulator. When water runs
out of the hose, you will see a steady stream of water
(without bubbles). Close balance and purge valve or
drain to stop the water from owing. Disconnect the
hose and connect it to next zone to be purged.
• Repeat this procedure for additional zones (one at a
time).
For installation that incorporates standing iron radiation and
systems with manual vents at the high points, follow previous
section and, starting with the nearest manual air vent, open
until water ows out. Then close vent. Repeat procedure,
working your way toward the furthest air vent. It may be
necessary to install a basket strainer in an older system where
larger amounts of sediment may be present. Annual cleaning
of the strainer may be necessary.
Upon completion, make sure that the ll valve is in the
automatic position and each zone balance and purge or shut
o is in an open position and zone valves are positioned for
automatic operation.
K. Freeze Protection Fluids
Use only inhibited glycol solutions which are specially
formulated for hydronic systems. Ethylene glycol is toxic and
can attack gaskets and seals used in hydronic systems. Glycol
mixtures should not exceed 50%.
1. Glycol in hydronic applications is specially formulated
for this purpose, and includes inhibitors that prevent the
glycol from attacking metallic system components. Make
certain that the system uid is checked for the correct glycol
concentration and inhibitor level.
2. The glycol solution should be tested at least once a year and
as recommended by the glycol manufacturer.
3. Anti-freeze solutions expand more than water. For
example: A 50% by volume solution expands 4.8% in volume
for a temperature increase from 32oF to 180oF, while water
increases 3% over the same temperature rise. Allowances
must be made for this expansion in the system design.
4. A 30% mixture of glycol will result in a BTU output loss of
15% with a 5% increase in head against the system circulator.
5. A 50% mixture of glycol will result in a BTU output loss of
30% with a 50% increase in head against the system circulator.
Basic steps are listed below that will guide the installation of the
boiler.
1. Connect the system return marked “Boiler Return”.
2. Connect the system supply marked “Boiler Supply”.
3. Install purge and balance valve or shut o valve and drain on
system return to purge air out of each zone.
4. Install a back ow preventer on the cold feed make-up water
line.
5. Install a pressure reducing valve on the cold feed make-
up water line (15 PSI nominal on the system return). Check
temperature and pressure gauge when operating. It should read
a minimum pressure of 12 PSI.
6. Install a circulator as shown in piping details (this section).
Make sure the circulator is properly sized for the system and
friction loss.
7. Install an expansion tank on the system supply. Consult
the tank manufacturer’s instructions for specic information
relating to expansion tank installation. Size the expansion tank
for the required system volume and capacity.
8. Install an air elimination device on the system supply.
9. Install a drain valve at the lowest point of the system. NOTE:
The boiler cannot be drained completely of water without
purging the unit with an air pressure of 15 PSI.
10. The relief valve is installed at the factory. A pipe discharge
line should be installed to discharge 6” above the drain in the
event of pressure relief. The pipe size must be the same size as
the relief valve outlet. NEVER BLOCK THE OUTLET OF THE
SAFETY RELIEF VALVE.
I. Plumbing
This boiler should not be operated as a potable hot water heater.
It should not be used as a direct hot water heating device.
Piping Components
Heating System Piping
System piping MUST be sized per technical pipe requirements
listed in Tables 6 and 7. Reducing pipe size can restrict ow rate
through the boiler, causing inadvertent short cycling and poor
system performance.
Check Valves
Field supplied. Check valves are recommended for installation
as shown in Applications.
Isolation Valves
Field supplied. Full port ball valves are required. Failure to use
full port ball valves could result in a restricted ow rate through
the boiler.
Anti-Scald Mixing Valve
Field supplied. An anti-scald mixing valve is recommended when
storing domestic hot water above 115°F.
Unions
Field supplied. Recommended for unit serviceability. DO
NOT USE DIELECTRIC UNIONS! ONLY BRASS, COPPER, OR
STAINLESS STEEL.
Pressure Relief Valve
Factory supplied on boiler. The pressure relief valve is sized to
ASME specications. Storage tank may require additional relief
valves depending on local codes.
Minimum Pipe Size
All Models 2” NPT
Table 7 - Minimum Pipe Size

WHL-033 Rev. 1.29.16
19
It is highly recommended that you carefully follow the glycol
manufacturer’s recommended concentrations, expansion
requirements, and maintenance recommendations (pH
additive breakdown, inhibitor reduction, etc.). Carefully
gure the additional friction loss in the system as well as the
reduction in heat transfer coecients.
L. Zoning with Zone Valves
1. When zoning with zone valves, connect the boiler to the
system as shown in Applications. The primary/secondary
piping shown ensures the boiler loop will have sucient ow.
It also avoids applying the high head of the boiler circulator to
the zone valves.
2. Connect DHW (domestic hot water) piping to indirect
storage water heater as shown in Applications.
M. Zoning with Circulators
1. When using circulator zoning, connect the boiler to the
system as shown in Applications. NOTE: The boiler circulator
cannot be used for a zone. It must only supply the boiler loop.
2. Install a separate circulator for each zone.
3. Connect DHW (domestic hot water) piping to indirect
storage water heater as shown in Applications.
N. Multiple Boilers
1. Connect multiple boilers as shown in Applications.
2. All piping shown is reverse return to assure balanced ow
throughout the connected boilers.
3. Each connected boiler must have its own circulator pump to
assure adequate ow.
4. Connect DHW (domestic hot water) piping to indirect
storage water heater as shown in Applications.
5. The system ow (secondary loop) must be greater than the
boiler’s primary loop ow.
Water temperature above 140oF requires the circulator
pump to run continuously and water hardness between 5
and 7 grains. Hardness above 7 grains will damage the heat
exchanger and shorten the service life of the boiler.

WHL-033 Rev. 1.29.16
20
O. Applications*
*NOTE: Systems shown are
primary/secondary piping
systems. These recommended
systems have a primary (boiler)
loop, and secondary circuits for
heating. The primary loop and
secondary circuits have separate
circulators. The use of other near
boiler piping congurations could
result in improper ow rates,
leading to inadvertent boiler high
limit shutdowns and poor system
performance.
NOTE: In piping applications
utilizing a single zone, it is
recommended that the installer
use ow / check valves with
weighted seats at or near the
appliance to prevent gravity
circulation.
FIGURE NOTES:
1. This drawing is meant to
demonstrate system piping concept
only.
2. A mixing valve is recommended if
the DHW temperature is set above
the factory setting of 119oF.
3. Install a minimum of 12 diameters
of straight pipe upstream of all
circulators.
4. Install a minimum of 6 diameters of
straight pipe up and downstream of
all closely spaced tees.
5. Piping shown is Primary/Secondary.
6. The minimum pipe size for
connecting an Westinghouse indirect
red water heater is 1”.
7. The minimum pipe size for
connecting a boiler is 2”.
8. System ow (Secondary Loop)
must be greater than the boiler’s
Primary Loop ow.
9. Installations must comply with all
local codes.
10. In Massachusetts, a vacuum relief
valve must be installed on the cold
water line per 248 CMR.
11. See Multiple Boiler Manifold
Piping chart, this manual, when
sizing and installing a multiple boiler
system.
The piping will not support the weight of the circulators. Refer to the circulator manufacturer’s instructions to properly support
the circulator. Failure to comply with these instructions could result in property damage, severe personal injury, or death.
An ASSE 1017 thermostatic mixing valve is recommended on all indirect water heaters if the hot water temperature leaving the
heater is above 119oF. Failure to do so could result in substantial property damage, serious injury, or death.
Figure 6 - Single Boiler Space Heating with Indirect Priority
Figure 7 - Cascaded Boilers with Indirect Priority on One