Williamson-Thermoflo GWC 2 Series Guide

Part number 550-142-804/1021
User’s Information
Manual
GWC
Series 2
Gas-Fired Water Boilers
If the information in this manual is not followed
exactly, a re or explosion may result, causing
property damage, personal injury or loss of life.
Do not store or use gasoline or other flammable va-
pors and liquids in the vicinity of this or any other appliance.
— WHAT TO DO IF YOU SMELL GAS —
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any telephone
in your building.
• Immediately call your gas supplier from a neighbor’s telephone.
Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the re department.
Installation & service must be performed by a qualied installer,
service technician or the gas supplier.

Part number 550-142-804/1021
2

e following dened terms are used throughout this manual to bring attention to the presence of hazards of various risk levels
or to important information concerning the life of the product.
Indicates presence of hazards that
will cause severe personal injury,
death or substantial property
damage.
Indicates presence of hazards that
can cause severe personal injury,
death or substantial property
damage.
Indicates presence of hazards that
will or can cause minor personal
injury or property damage.
Indicates special instructions
on installation, operation or
maintenance that are important but
not related to personal injury or
property damage.
e Boiler manual is for use only by a qualied heating installer/
service technician. Refer only to this User’s Information Manual for
your reference. Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal injury (exposure
to hazardous materials) or loss of life. Installation and service must be
performed by a qualied installer, service agency or the gas supplier
(who must read and follow the supplied instructions before install-
ing, servicing, or removing this boiler. is boiler contains materials
that have been identied as carcinogenic, or possibly carcinogenic,
to humans).
When calling or writing
about the boiler— Please
have the boiler model
number from the boiler
rating label and the CP
number from the label
located on the top of the
boiler next to the air inlet
connection.


How to use this
manual . . . To . . . Read/use . . . Page . . .
Learn
precautions  3
Prevent air
contamination
Laundry room or pool — make sure boiler air is
piped to boiler per manual.
Read list of air contaminants you must avoid. Have
boiler air piped in if you can’t avoid.
4
Maintain
boiler
Set up a plan for maintaining the boiler using
the schedule included in this manual.
Schedule an annual start-up by a qualied
service technician before every heating season.
5
Locate boiler
components How the boiler works and illustration. 10
Start — or —
Shutdown
boiler
Follow the Operating instruction sheet details to
start or shutdown your boiler. 12
Troubleshoot
common
problems
Use the common problems/solutions table to
resolve typical heating system/boiler problems. 13
GWC User’s Information Manual

Part number 550-142-804/1021 3

User — Have this boiler serviced/inspected by
a qualied service technician, at least annually.
Failure to adhere to the guidelines on this page
can result in severe personal injury, death or
substantial property damage.
Boiler service and maintenance —
• To avoid electric shock, disconnect all electrical supplies
to the boiler before performing maintenance if wiring will
be exposed.
• To avoid severe burns, allow boiler to cool before perform-
ing maintenance.
• You must maintain the boiler as outlined in this manual
and have the boiler started up and serviced at least an-
nually by a qualied service technician to ensure boiler/
system reliability.
Boiler operation —
• Do not block ow of combustion or ventilation air to
boiler. is boiler is equipped with a control which will
automatically shut down the boiler should air or vent be
blocked. If vent or air blockage is easily accessible and
removable, remove it. e boiler should attempt to restart
within an hour. (If blockage is not obvious or cannot
be removed, have the boiler and system checked by a
qualied service technician.)
• Do not allow contaminated air to enter the boiler room (or
air inlet pipe if direct vented). See page4 for details.
• Should overheating occur or gas supply fail to shut o, do
not turn o or disconnect electrical supply to boiler. Instead,
shut o the gas supply at a location external to the appliance.
• Do not use this boiler if any part has been under water.
Immediately call a qualied service technician to inspect
the boiler and to replace any part of the control system and
any gas control that has been under water.
• 󰀨,
DO NOT turn o or disconnect electrical supply to circula-
tor. Instead, shut o the gas supply at a location external to
the appliance.
Combustion air —
• DO NOT install combustion air intake where there is a
risk of combustion air contamination.
Carbon monoxide detector —
• For Direct Exhaust units, a carbon monoxide detector is
required in the boiler room. e carbon monoxide detector
must be wired on the same electrical circuit as the boiler.
• For Direct Vent units, a carbon monoxide detector that is
wired on the same electrical circuit as the boiler is strongly
recommended.
Boiler water —
• Have boiler water chemistry checked at least annually by a
qualied service technician.
• DO NOT use petroleum-based cleaning or sealing com-
pounds in boiler system. Gaskets and seals in the system may
be damaged. is can result in substantial property damage.
• DO NOT use “homemade cures” or “boiler patent medi-
cines”. Serious damage to boiler, personnel and/or property
may result.
• Leaks in boiler or piping must be repaired at once to
prevent make-up water. Use this boiler ONLY in a closed-
loop system. Continual fresh make-up water will reduce
boiler life. Mineral buildup in heat exchangers reduces
heat transfer, overheats the materials, and causes failure.
Addition of oxygen carried in by make-up water can cause
internal corrosion.
• Do not add cold water to hot boiler. ermal shock can
cause boiler heat exchanger to crack.

• NEVER use automotive or standard glycol antifreeze. Use
only freeze-protection uids made for hydronic systems.
Follow all guidelines given by the antifreeze manufacturer.
oroughly clean and ush any replacement boiler system
that has used glycol before installing the new boiler.
Frozen Water Damage Hazard
Residences or buildings that are unattended in severely cold
weather, boiler system components failures, power outages, or
other electrical system failures could result in frozen plumbing
and water damage in a matter of hours. For your protection, take
preventative actions such as having a security system installed
that operates during power outages, senses low temperature, and
initiates an eective action. Consult with your boiler contractor
or a home security agency.
If any part of a boiler, burner or its con-
trols has been sprayed with or submerged
under water, either partially or fully, DO
NOT attempt to operate the boiler until the
boiler has been either replaced or com-
pletely repaired, inspected, and you are
sure that the boiler and all components
are in good condition and fully reliable.
Otherwise, by operating this boiler, you will
cause a re or explosion hazard, and an electrical
shock hazard, leading to serious injury, death, or
substantial property damage. See the instructions
at right.
Saltwater Damage — e exposure of boiler components to
saltwater can have both immediate and long-term eects. While
the immediate eects of saltwater damage are similar to those
of freshwater (shorting out of electrical components, washing
out of critical lubricants, etc.), the salt and other contaminants
le behind can lead to longer term issues aer the water is gone
due to the conductive and corrosive nature of the salt residue.
erefore, Weil-McLain equipment contaminated with saltwater
or polluted water will no longer be covered under warranty and
should be replaced.
Electrical Damage — If any electrical component or
wiring came into contact with water, or was suspected to have
come into contact with water, replace the boiler with a new
Weil-McLain boiler.
GWC User’s Information Manual

Part number 550-142-804/1021
4

Common household and hobby products oen contain
uorine or chlorine compounds. When these chemicals
pass through the boiler, they can form strong acids in
the vent system or boiler. e acid can eat through the
vent or boiler wall, causing serious damage and present-
ing a possible threat of ue gas spillage into the building.
Please read the information below. If the contaminating
chemicals will be present, have your installer pipe the
boiler air from outside per the Boiler manual.
If the boiler is installed in any area
likely to cause contamination, or if
products which would contaminate the
air cannot be removed, you must pipe
combustion air to the boiler air intake.
Contaminated combustion air will dam-
age the boiler and vent system, resulting
in possible severe personal injury, death
or substantial property damage.
Do not operate a GWC boiler in a laun-
dry room or pool facility, for example,
without using ducted outside air. ese
areas will always contain contaminants.

Ensure that the combustion air will not contain any of
the contaminants in Figure 1.
Combustion air supply openings or intake terminations
must NOT be near a swimming pool, for example.
Avoid areas subject to exhaust fumes from laundry facili-
ties. ese areas will always contain contaminants.
Figure 1 Corrosive contaminants and sources
Products to avoid
Spray cans containing chloro/uorocarbons
Permanent wave solutions
Chlorinated waxes/cleaners
Chlorine-based swimming pool chemicals
Calcium chloride used for thawing
Sodium chloride used for water softening
Refrigerant leaks
Paint or varnish removers
Hydrochloric acid/muriatic acid
Cements and glues
Antistatic fabric softeners used in clothes dryers
Chlorine-type bleaches, detergents, and cleaning solvents found in
household laundry rooms
Adhesives used to fasten building products and other similar products
Excessive dust and dirt
Areas likely to have contaminants
Dry cleaning/laundry areas and establishments
Swimming pools
Metal fabrication plants
Beauty shops
Refrigeration repair shops
Photo processing plants
Auto body shops
Plastic manufacturing plants
Furniture renishing areas and establishments
New building construction

GWC User’s Information Manual

Part number 550-142-804/1021 5
Figure 2 Service and maintenance schedules

Service technician
(see Boiler Manual for instructions)
Owner maintenance
(see following pages for instructions)
Annual start-up


Daily
• Check boiler area
• Check air openings
• Check pressure gauge
Monthly
• Check boiler interior piping
• Check venting system
• Check air vents
• Check condensate drain system
• Check relief valve
Periodically
• Test low water cuto󰀨 (if used)
• Clean vent termination/air intake
screens
Every 6 months • Oil blower motor
• Operate relief valve
End of season • Shut down procedure
GWC User’s Information Manual

Part number 550-142-804/1021
6
DAILY





To prevent potential of severe personal injury, death or substantial property
damage, eliminate all materials discussed below from the boiler vicinity. If con-
taminants are found:
Remove products immediately from the area. If they have been there for an ex-
tended period, call a qualied service technician to inspect the boiler and vent
system for possible damage from acid corrosion.
If products cannot be removed, immediately call a qualied service technician to
install an outside combustion air source for the boiler (if not already installed).
1. Combustible/ammable materials — Do not store combustible materials, gasoline or any
other ammable vapors or liquids near the boiler. Remove immediately if found.
2. Air contaminants — Products containing chlorine or uorine, if allowed to contaminate
the boiler intake air, will cause acidic condensate in the vent and boiler. is will cause
signicant damage to the vent and/or boiler if allowed to continue. Read the list of potential
materials listed on page 4 of this manual. If any of these products are in the room from
which the boiler takes its combustion air, they must be removed immediately or the boiler
combustion air must be supplied from outside. See WARNING above.

1. Verify that combustion and ventilation air openings to the boiler room and/or building are
open and unobstructed.
2. Verify that boiler vent discharge and air intake are clean and free of obstructions. Remove
any debris on the air intake or ue exhaust openings.

1. Make sure the pressure reading on the boiler pressure/temperature gauge does not exceed
24 psig. Higher pressure may indicate a problem with the expansion tank.
2. Contact a qualied service technician if problem persists.
e boiler should be inspected and started annually, at the beginning of the heat-
ing season, only by a qualied service technician. In addition, the maintenance
and care of the boiler designated on page 5 and explained on the following pages
must be performed to assure maximum boiler eciency and reliability. Failure
to service and maintain the boiler and system could result in equipment failure,
causing possible severe personal injury, death or substantial property damage.
e following information provides detailed instructions for completing the
maintenance items listed in the maintenance schedule, page 5. In addition to
this maintenance, the boiler must be serviced and started up at the beginning of
each heating season by a qualied service technician.

GWC User’s Information Manual

Part number 550-142-804/1021 7



1. Remove boiler jacket top.
2. Visually inspect for leaks around internal piping, circulators, relief valve and other ttings.
Immediately call a qualied service technician to repair any leaks.
Have leaks xed at once by a qualied service technician. Continual fresh makeup
water will reduce boiler life. Minerals can build up in sections, reducing heat
transfer, overheating cast iron, and causing section failure.
Do not use petroleum-based cleaning or sealing compounds in boiler system.
Severe damage to boiler and system components can occur, resulting in possible
severe personal injury, death or substantial property damage.

1. Visually inspect the ue gas vent piping for any signs of blockage, leakage or deterioration
of the piping. Notify your qualied service technician at once if you nd any problem.
Failure to inspect the vent system as noted above and have them repaired by
a qualied service technician can result in vent system failure, causing severe
personal injury or death.


1. See Figure3.
2. Remove the cap from any automatic air vent in the system and check operation by depress-
ing valve “B” slightly with the tip of a screwdriver.
3. If the air vent valve appears to be working freely and not leaking, replace cap “A”, twisting
all the way on.
4. Loosen cap “A” one turn to allow vent to operate.
5. Have vent replaced if it does not operate correctly.
Figure 3 Automatic air vent
85036
A
B
(continued)
GWC User’s Information Manual

Part number 550-142-804/1021
8


1. NOTICE — To improve clarity, this
illustration of the condensate trap is
shown with no air inlet pipe attached.
If your boiler has an air pipe connected
here, DO NOT tamper with it. e trap
is also shown as itemon page11.
2. Inspect the condensate P-trap (item1 in
the illustration at right). If the trap does
not contain water, turn o the boiler
ON/OFF switch and call your boiler
service technician immediately.
3. Item 2 in the illustration is the drain
tubing to the condensate pump. Inspect
this tubing or piping, making sure it is
in good condition and not obstructed.
If the condensate trap is dry or the condensate line is damaged or obstructed,
there is a risk of ue gas ow into the building. e boiler must not be operated
and must be inspected and serviced only by a qualied service technician. Failure
to comply with this directive could result in the possibility of severe personal
injury, death or substantial property damage.

1. Inspect the boiler relief valve and the relief valve discharge pipe for signs of weeping or
leakage.
2. If the relief valve oen weeps, the expansion tank may not be working properly. Immediately
contact your qualied service technician to inspect the boiler and system.

1. If the system is equipped with a low water cuto, test the low water cuto periodically
during the heating season, following the low water cuto manufacturer’s instructions.

1. Remove all lint and debris from both the boiler air intake screen and the ue discharge
screen.
2. e boiler control module will sense blockage of the air intake or ue and lockout if the
blockage is excessive. It will signal the failure by ashing the appropriate indicator lights
on the control board.
3. If removing the debris does not allow the boiler to operate correctly aerwards, contact
your qualied service technician to inspect the boiler and vent/air systems.


PERIODIC

(continued)
GWC User’s Information Manual

Part number 550-142-804/1021 9

1. Before proceeding, verify that the relief valve outlet has been piped to a safe place of dis-
charge, avoiding any possibility of scalding from hot water.
To avoid water damage or scalding due to valve operation, a metal discharge
line must be connected to relief valve outlet and run to a safe place of disposal.
is discharge line must be installed by a qualied heating installer or service
technician in accordance with the instructions in the GWC Boiler Manual. e
discharge line must be terminated so as to eliminate possibility of severe burns
should the valve discharge.
2. Read the boiler pressure/temperature gauge to make sure the system is pressurized.
3. Li the relief valve top lever slightly, allowing water to relieve through the valve and dis-
charge piping.
4. If water ows freely, release the lever and allow the valve to seat. Watch the end of the relief
valve discharge pipe to ensure that the valve does not weep aer the line has had time to
drain. If the valve weeps, li the seat again to attempt to clean the valve seat. If the valve
continues to weep aerwards, contact your qualied service technician to inspect the valve
and system.
5. If water does not ow from the valve when you li the lever completely, the valve or discharge
line may be blocked. Immediately shutdown the boiler, following the lighting instructions
on the inside jacket top. Call your qualied service technician to inspect the boiler and
system.

1. Follow “TO TURN OFF GAS TO APPLIANCE” on the Operating instruction on the inside
of the jacket top panel. You will also nd these instructions on page12 of this manual.
2. Do not drain system unless exposure to freezing temperatures will occur.
3. Do not drain the system if it is lled with an antifreeze solution.
4. Do not shut down boilers used for domestic water heating. ey must operate year-round.

1. Remove the jacket top panel to access the blower
motor.
2. Use only Anderol465. DO NOT use household
universal oils.
Use only Anderol 465 to lubricate the
blower motor. Do not use common uni-
versal household oils.
3. See Figure4
4. Place a few drops of oil in each of the two oiler cups
on the side of the blower motor.
Figure 4 Blower motor
EVERY





(continued)
GWC User’s Information Manual

Part number 550-142-804/1021
10
LEGEND
a Supply to system, 1”NPT
b Return from system, 1”NPT
c Combustion air inlet tting —
3”PVC connection
d Flue outlet — 3”PVC connection
e Gas valve — negative pressure
regulated gas control
f Pressure/temperature gauge
g Flueway inspection port cover
h Sensor hose trap
i Manual air vent
j Relief valve
k ermal switch — a device that
shuts boiler o if ue tempera-
ture exceeds its setpoint
l Condensate trap line — shipped
loose with boiler, eld installed
This boiler uses a negative-pressure-
regulated gas valve, set for an outlet
pressure approximately –0.20” water
column.
DO NOT set the outlet pressure higher
than factory setting.
1 Integrated boiler control
e integrated boiler control (IBC) responds to signals from the room thermostat, air
pressure switch, inlet water sensor, boiler water temperature sensor and boiler limit circuit
to operate the circulators, gas valve, igniter and blower. When a room thermostat calls
for heat, the IBC starts the system circulator and blower.
e IBC runs the blower to purge the boiler ue passages, then turns on the igniter and
lets it warm up.
Aer igniter warm-up, the IBC opens the gas valve, turns the igniter o, and checks for
ame. e ame must come on within 4 seconds or the IBC will shut down and try the
full cycle again.
When the room thermostat is satised, the IBC turns o the boiler components and
waits for the next heat call.
e IBC indicator lights show normal sequence when the lights are on steady. When a
problem occurs, the IBC ashes combinations of lights which indicate the most likely
reason for the problem.
While attempting to satisfy the heat demand, the control module monitors the boiler
temperature changes via the temperature sensors and determines whether or not the
available hot water will satisfy the demand, only running the circulator. If additional
heat is needed, the sequence continues. When DHW (if used) calls for heat, sequence
above is bypassed.
2 Transformer
e control transformer reduces line voltage to 24 volts for the gas valve and limit circuit.
3 Blower
e blower pulls in air and mixes it with gas from the gas valve. e blower forces this
mixture into the burner for combustion inside the boiler chamber.
4 Recuperator
e recuperator is a stainless steel heat exchanger that increases boiler eciency by ex-
tracting additional heat from the ue gases. Return water passes through the recuperator
before entering the boiler.
5Water temperature sensor
e water temperature sensor provides a signal to the control module to turn
o the gas valve if the temperature in the boiler goes above its setting. (e
circulator will continue to run as long as there is a call for heat.)
6 System circulator
e system circulator circulates water through the external (system) piping. e ow
rate of the circulator is controlled by the IBC, depending on the temperature of the water
entering the boiler sections. Pump must remain on boiler — do not remove.
7 Bypass circulator
e IBC operates the bypass circulator to mix hot water from the boiler outlet with
colder return water from the system as needed to prevent condensation of ue gases in
the cast iron heat exchanger.
When the water returning to the boiler is below 140°F, the IBC regulates the bypass
circulator and system circulator ow rates to raise the return water temperature up to
140°F before it enters the cast iron sections. By balancing these ow rates, the IBC can
protect against condensation even if return water is as low as 60°F.
Pump must remain on boiler — do not remove.
8 Air pressure switch
e air pressure switch signals the IBC, telling the control whether air is moving through
the blower.
9 Return water temperature sensor
e water temperature sensor monitors the temperature of the water entering the boiler
sections. e sensor sends this information to the IBC. e IBC determines how much
to adjust the circulator ow rates to provide at least 140°F water to the cast iron heat
exchanger.

GWC User’s Information Manual

Part number 550-142-804/1021 11
GWC Series 2 Water Boiler
GWC User’s Information Manual

Part number 550-142-804/1021
12
Figure 5 Operating instructions

Before attempting to start the boiler, check the boiler pressure temperature gauge. If boiler and system are full of
water and properly pressurized, the gauge should read at least 12 psig on most systems. Operating the boiler without
proper water content will damage boiler and controls and could result in severe personal injury, death or substantial
property damage.
GWC User’s Information Manual

Part number 550-142-804/1021 13

  
Rapid cycling — boiler turns
󰀨
Thermostat installed where drafts
or heat a󰀨ect reading
Locate thermostat on inner wall away from
heat sources or cool drafts.
Heat anticipator in thermostat
adjusted incorrectly
Adjust thermostat per manufacturer’s
instructions.
Incorrect boiler temperature
setting
Set boiler temperature according to system
needs. Maximum setting is 200°F. Increase
boiler temperature setting to decrease
cycling.
Insu󰀩cient water ow through
boiler
Check all valves to and from boiler. Return
to proper setting.
Conrm circulator size.

through relief valve
Expansion tank sized too small Call qualied service technician to check
expansion tank operation and size.
Flooded expansion tank Call qualied service technician to check
expansion tank operation.
Inoperative limit control Call qualied service technician to replace
limit control.

makeup water
Leaks in boiler or piping Have qualied service technician repair
leaks at once to avoid constant use of
makeup water. Makeup water can cause
mineral deposits which, in turn, can
cause boiler section failure. Do not use
petroleum-base stop-leak compounds.
Black water condition Oxygen corrosion due to leaks in
boiler and piping
Have qualied service technician repair
at once. Keep pH of water between 7.0 to
8.5.
Large temperature swings in
living space
Incorrect Economy setting Adjust Economy setting on boiler control.
GWC User’s Information Manual

Part number 550-142-804/1021
14
(continued)
  
Popping or percolating noise
heard in boiler
Mineral deposits in sections due
to constant use of makeup water
Call qualied service technician to de-
lime boiler, if necessary. In some cases,
deposits will be too heavy to remove with
de-liming procedures.
Have qualied service technician repair
leaks to eliminate need for constant
makeup water.
Incorrect pH of boiler water Call qualied service technician to check
pH level and correct. pH should be
maintained between 7.0 to 8.5.
Insu󰀩cient water ow through
boiler
Check all valves to and from boiler. Return
to proper setting.
Conrm circulator size.

outlet or vent starter tee —

Contaminated combustion air
supply — See page 4 in this
manual.
Remove any contaminating products. See
page 4 in this manual.
Provide outside air for combustion. Have
qualied service technician pipe-up kit.
Condensation of combustion
gases in boiler sections
Have qualied service technician check
operation of mixing system. Repair/
replace if necessary.
Some radiators or baseboard
units do not heat or are
noisy
Air in system Bleed air from system through air vents in
radiators or baseboard units.
Low system pressure Fill to correct pressure.
Check for leaks in boiler or piping. Have
qualied service technician repair at once.
Boiler temperature set too low Adjust boiler temperature to higher setting.
GWC User’s Information Manual

Part number 550-142-804/1021 15

GWC User’s Information Manual

Part number 550-142-804/1021
GWC User’s Information Manual