Weil-McLain GOLD CGa User manual

Part No. 550-101-009/0107
This manual must only be used by a qualified heating installer/service technician. Before installing, read all
instructions, including this manual, the burner manual and any related supplements. Perform steps in the order
given. Failure to comply could result in severe personal injury, death or substantial property damage.
GOLD CGa
• Installation
• Startup
Boiler Manual • Maintenance
• Parts
Gas-Fired Water Boilers

GOLD CGa Gas-Fired Water Boiler — Boiler Manual
2Part Number 550-101-009/0107
How it works . . .
①Control module
The control module (used on spark-ignited pilot boilers) responds to signals from the room thermostat and
boiler limit circuit to operate the boiler circulator, pilot burner, gas valve and vent damper. When room thermostat
calls for heat, the control module starts the system circulator and activates the vent damper (causing it to drive
open).
When the vent damper has opened completely, the control module opens the pilot valve and activates pilot igni-
tion spark.
The control module allows up to 15 seconds to establish pilot flame. If flame is not sensed within 15 seconds, the
control module will turn off the gas valve, flash the Flame light, and immediately start a new cycle. This will con-
tinue indefinitely until pilot flame is established or power is interrupted. Once pilot flame is proven, the control
module opens the gas valve to allow main burner flame.
When the room thermostat is satisfied, the control module turns off the gas valve and deactivates the vent damper
(causing it to close).
The control module indicator lights show normal sequence when the lights are on steady. When a problem oc-
curs, the control module flashes combinations of lights to indicate the most likely reason for the problem. See
page 52 for details.
Standing pilot boilers (controls not shown) use the pilot thermocouple to prove flame. If the thermocouple
is satisfied, the gas valve and vent damper will open on a call for heat and close afterwards.
②Transformer
The control transformer reduces line voltage to 24 volts for the gas valve and limit circuit.
③Draft hood
The draft hood provides a minimum draft for the boiler, assuring adequate air for combustion if installed in ac-
cordance with manual and not modified in any way.
④Spill switch
The spill switch will shut down the boiler (requiring manual reset of the switch reset button) if the vent system
becomes blocked.
⑤Water temperature limit switch
The water temperature limit switch turns off the gas valve if the temperature in the boiler goes above its setting.
(The circulator will continue to run as long as there is a call for heat.)
⑥Boiler circulator
The boiler circulator circulates water through the external (system) piping. The circulator is shipped loose, and can
be mounted on either the boiler supply or return piping. The factory-installed circulator wiring harness provides
ample length for either location. NOTE — The control module provides a pump exercising routine. If the boiler
is not operated for 30 days, the control module will power the circulator for 30 seconds, then turn off.
⑦Vent damper
The vent damper closes during off cycles to reduce heat loss from the house up the vent.
a supply to system
b return from system
c flue outlet
d burner manifold
e gas valve
f pressure/temperature gauge
g relief valve
h air vent connection
i flame rollout switch
j burner orifice
k pilot burner, typical
l stainless steel burners
m cast iron boiler sections
n flue collector
o junction box
Other boiler components:

Part Number 550-101-009/0107 3
GOLD CGa Gas-Fired Water Boiler — Boiler Manual
GOLD CGa Gas-Fired Water Boiler

GOLD CGa Gas-Fired Water Boiler — Boiler Manual
4Part Number 550-101-009/0107
Contents
Hazard definitions
The following defined 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 dam-
age.
Indicates special instructions on installation, operation or maintenance that are important but
not related to personal injury or property damage.
How is works .................................................... 2-3
Hazard definitions ............................................... 4
Please read before proceeding ............................ 5
1 Prepare boiler location ...................................6–11
2 Prepare boiler............................................... 12-15
3 Water piping ................................................. 16-25
4 Gas piping ......................................................... 26
5 Field wiring ....................................................... 27
6 Start-up ........................................................ 28-32
7 Check-out procedure......................................... 33
8 Operation – standing pilot boilers................. 34-36
9 Operation – spark-ignited pilot boilers.......... 37-43
10 Service and maintenance ............................. 44-49
11 Troubleshooting:
Standing pilot boilers ............................. 49-50, 51
Spark-ignited pilot boilers .................49-50, 51-59
12 Replacement parts ....................................... 60-65
13 Dimensions and ratings ................................ 66-67

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GOLD CGa Gas-Fired Water Boiler — Boiler Manual
Failure to adhere to the guidelines on this page can result in severe personal injury, death
or substantial property damage.
Please read before proceeding
• Continual fresh makeup water will reduce
boiler life. Mineral buildup in sections re-
duces heat transfer, overheats cast iron, and
causes section failure. Addition of oxygen
and other gases can cause internal corrosion.
Leaks in boiler or piping must be repaired
at once to prevent makeup water.
• Do not add cold water to hot boiler. Thermal
shock can cause sections to crack.
Glycol — potential fire hazard —
All glycol is flammable when exposed to high
temperatures. If glycol is allowed to accumulate
in or around the boiler or any other potential
ignition source, a fire can develop. In order to
prevent potential severe personal injury, death
or substantial property damage from fire and/or
structural damage:
• Never store glycol of any kind near the boiler
or any potential ignition source.
• Monitor and inspect the system and boiler
regularly for leakage. Repair any leaks im-
mediately to prevent possible accumulation
of glycol.
• Never use automotive antifreeze or ethylene
glycol in the system. Using these glycols can
lead to hazardous leakage of glycol in the
boiler system.
When servicing boiler —
• To avoid electric shock, disconnect electrical supply
before performing maintenance.
• To avoid severe burns, allow boiler to cool before
performing maintenance.
Boiler operation —
• Do not block flow of combustion or ventilation air
to boiler.
• Should overheating occur or gas supply fail to shut
off, do not turn off or disconnect electrical supply to
circulator. Instead, shut off 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 qualified service techni-
cian to inspect the boiler and to replace any part of
the control system and any gas control that has been
under water.
Boiler water —
• Do not use petroleum-based cleaning or sealing
compounds in boiler system.Water seal deterioration
will occur, causing leakage between sections. This 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.
Installer
Read all instructions before in-
stalling. Follow all instructions in
proper order to prevent personal
injury or death.
• Consider piping and installation when determining
boiler location.
• Any claims for damage or shortage in shipment
must be filed immediately against the transportation
company by the consignee.
User
• This manual is for use only by your qualified
heating installer/service technician.
• Please refer to the User’s Information Manual for
your reference.
• We recommend regular service by a qualified
service technician, at least annually.
When calling or writing about the boiler— Please have the boiler model number from the
boiler rating label and the CP number from the boiler jacket. You may list the CP number in
the space provided on the Installation and service certificate found on page 33.
The boiler contains ceramic fiber and fiberglass materials. Use care when handling these
materials per instructions on page 68 of this manual. Failure to comply could result in severe
personal injury.

GOLD CGa Gas-Fired Water Boiler — Boiler Manual
6Part Number 550-101-009/0107
Prepare boiler location — codes & checklist
1a
Installations must follow these codes:
• Local, state, provincial, and national codes, laws, regulations and ordinances.
• National Fuel Gas Code, ANSI Z223.1–latest edition.
• Standard for Controls and Safety Devices for Automatically Fired Boilers, ANSI/
ASME CSD-1, when required.
• National Electrical Code.
• For Canada only: B149.1 or B149.2 Installation Code, CSA C22.1 Canadian
Electrical Code Part 1 and any local codes.
The CGa boiler gas manifold and controls met safe lighting and
other performance criteria when boiler underwent tests specified
in ANSI Z21.13–latest edition.
Before locating the boiler,
check the following:
• Check for nearby connection to:
• System water piping
• Venting connections
• Gas supply piping
• Electrical power
• Check area around boiler. Remove any combustible materials, gasoline and
other flammable liquids, or other contaminants.
Failure to keep boiler area clear and free of combustible mate-
rials, gasoline and other flammable liquids and vapors can
result in severe personal injury, death or substantial property
damage.
• Boiler must be installed so that gas control system components are protected
from dripping or spraying water or rain during operation or service.
• If new boiler will replace existing boiler, check for and correct system problems,
such as:
1. System leaks causing oxygen corrosion or section cracks from hard water
deposits.
2. Incorrectly-sized expansion tank.
3. Lack of antifreeze in boiler water causing system and boiler to freeze and
leak.

Part Number 550-101-009/0107 7
GOLD CGa Gas-Fired Water Boiler — Boiler Manual
Prepare boiler location — clearances
1b
Figure 1b Required MINIMUM clearances
Figure 1a
Recommended
service
clearances
(see WARNING
below)
Recommended SERVICE clearances
(Fig. 1a)
1. Provide clearances for cleaning and servicing the boiler and for
access to controls and components. See Figure 1a for recommen-
dations.
2. Provide at least screwdriver clearance to jacket front panel screws
for removal of front panel for inspection and minor service. If
unable to provide at least screwdriver clearance, install unions and
Required MINIMUM clearances (Fig. 1b)
Never install the boiler in a space with clear-
ances less than the minimum clearances shown
in Figure 1b. Failure to comply can result in severe
personal injury, death or substantial property dam-
age and reduced boiler life.
1. Hot water pipes: at least ¹⁄₂ inch from combustible material.
2. Single-wall vent pipe: at least 6 inches from combustible mate-
rial.
3. Type B double-wall metal vent pipe: refer to vent manufacturer’s
recommendation for clearances to combustible material.
If any clearance is less than in Figure 1a,
provide openings for combustion and
ventilation air located on the wall or door
opposite the boiler FRONT (see Figure 1b).
These openings must be located as shown in Figure 1b to provide
proper air flow around the boiler. The free area of each opening
(after deducting for louvers) must be at least one square inch
per 1,000 Btuh of boiler input. If the building is of unusually
tight construction (see page 11 for definition), the air openings
must connect directly to outside or the building must have air
openings to the outside as specified on page 11.
If clearances are equal to or greater than Figure 1a, see pages 10
and 11 for location and sizing of combustion air openings.
Failure to comply can result in severe personal injury, death or
substantial property damage and reduced boiler life.
Flooring
The CGa boiler is approved for installation on combustible
flooring, but must never be installed on carpeting.
Do not install boiler on carpeting even
if foundation is used. Fire can result,
causing severe personal injury, death
or substantial property damage.
Foundation
1. Provide a solid brick or minimum 2-inch thick concrete
foundation pad if any of the following is true:
• floor can become flooded.
• the boiler mounting area is not level.
2. Minimum dimensions are 25” length by:
Residential garage installations
Take the following special precautions when installing the
boiler in a residential garage. If the boiler is located in a
residential garage, per ANSI Z223.1:
• Mount the boiler a minimum of 18 inches above the
floor of the garage to assure the burner and ignition
devices will be no less than 18 inches above the floor.
• Locate or protect the boiler so it cannot be damaged
by a moving vehicle.
Minimum foundation width:
CGa-25/3 12" CGa-6 21"
CGa-4 15" CGa-7 24"
CGa-5 18" CGa-8 27"

GOLD CGa Gas-Fired Water Boiler — Boiler Manual
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Prepare boiler location — vent system
1c
Failure to follow all instructions can result in flue gas spillage and carbon monoxide emissions, causing severe
personal injury or death.
When removing boiler from an
existing common vent system:
At the time of removal of an existing boiler, the following
steps shall be followed with each appliance remaining
connected to the common venting system placed in op-
eration,while the other appliances remaining connected
to the common venting system are not in operation.
a. Seal any unused openings in the common venting
system.
b. Visually inspect the venting system for proper
size and horizontal pitch and determine there is no
blockage or restriction, leakage, corrosion or other
deficiencies which could cause an unsafe condi-
tion.
c. Test vent system — Insofar as is practical, close all
building doors and windows and all doors between
the space in which the appliances remaining con-
nected to the common venting system are located
and other spaces of the building. Turn on clothes
dryers and any appliance not connected to the com-
mon venting system.Turn on any exhaust fans,such
as range hoods and bathroom exhausts, so they will
operate at maximum speed. Do not operate a sum-
mer exhaust fan. Close fireplace dampers.
d. Place in operation the appliance being inspected.
Follow the lighting/operating instructions. Adjust
thermostat so appliance will operate continuously.
e. Test for spillage at draft hood relief opening after
5 minutes of main burner operation. Use the flame
of a match or candle.
f. After it has been determined that each appliance
remaining connected to the common venting system
properly vents when tested as outlined above,return
doors, windows, exhaust fans, fireplace dampers,
and any other gas-burning appliance to their previ-
ous conditions of use.
Any improper operation of common venting system
should be corrected so the installation conforms with
the National Fuel Gas Code,ANSI Z223.1-latest edition.
Correct by resizing to approach the minimum size as
determined using the appropriate tables in Part 11 of
that code. Canadian installations must comply with
B149.1 or B149.2 Installation Code.
Chimney or vent require-
ments
1. Venting must be installed according to Part 7, Vent-
ing of Equipment, of National Fuel Gas Code, ANSI
Z223.1-latest edition and applicable building codes.
Canadian installations must comply with B149.1 or
B149.2 Installation Codes.
2. See Ratings table on page 67 for minimum chimney
or vent sizes. A chimney or vent without a listed
cap should extend at least 3 feet above the highest
point where it passes through a roof of a building
and at least 2 feet higher than any portion of a
building within a horizontal distance of 10 feet.
A chimney or vent must not extend less than the
distances stated above.
3. A lined chimney is preferred and must be used when
required by local, state, provincial and national
codes, laws, regulations and ordinances.Vitreous tile
linings with joints that prevent retention of moisture
and linings made of noncorrosive materials are best.
Advice for flue connections and chimney linings can
be obtained from local gas utility. Type B double-
wall metal vent pipe or single-wall vent pipe may
be used as a liner.
4. Cold masonry chimneys, also known as outside
chimneys, typically have one or more walls ex-
posed to outside air. When any atmospheric gas-
fired boiler with automatic vent damper is vented
through this type of chimney, the potential exists for
condensation to occur. Condensation can damage
a masonry chimney. Weil-McLain recommends the
following to prevent possible damage.
a. Line chimney with corrosion-resistant metal
liner such as AL29-4C® single-wall stainless
steel or B-vent. Size liner per National Fuel
Gas Code ANSI Z223.1-latest edition.
b. Provide drain trap to remove any condensate.
5. Where two or more gas appliances vent into a
common chimney or vent, equivalent area should
be at least equal to area of vent outlet on largest
appliance plus 50 percent of vent outlet area on
additional appliance.
Do not alter boiler draft hood or place any obstruction or non-approved vent damper in breeching or vent system.
CSA certification will become void. Flue gas spillage and carbon monoxide emissions will occur causing severe
personal injury or death.
Inspect existing chimney before installing boiler. Failure to clean or replace perforated pipe or tile lining will cause
severe personal injury or death.

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GOLD CGa Gas-Fired Water Boiler — Boiler Manual
Prepare boiler location — air contamination
Table 1 Corrosive contaminants and likely locations
1d
Please review the following information on potential
combustion air contamination problems.
Refer to Table 1 for products and areas which may cause
contaminated combustion air.
To prevent potential of severe personal injury or death, check for products or areas listed
below before installing boiler. If any of these contaminants are found:
• remove contaminants permanently
— OR —
• isolate boiler and provide outside combustion air. See national, provincial or local codes
for further information.
Products to avoid Areas likely to have contaminants
Spray cans containing chloro/fluorocarbons 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 acid/muriatic acid Furniture refinishing areas and establishments
Cements and glues New building construction
Antistatic fabric softeners used in clothes dryers Remodeling areas
Chlorine-type bleaches, detergents, and cleaning
solvents found in household laundry rooms Garages with workshops
Adhesives used to fasten building products and
other similar products
Buildings under construction (where air is
contaminated with particulates)
Airborne particulates (drywall dust, fiberglass
particles, road or gravel dust, lint, etc.)

GOLD CGa Gas-Fired Water Boiler — Boiler Manual
10 Part Number 550-101-009/0107
Figure 5 Air from outdoors — horizontal ducts
Figure 4 Air from outdoors — vertical ducts
Figure 2 Air openings to interior spaces
Figure 3 Air directly through outside wall
Air opening options
Two openings — Air supply from inside the building ✷
1. If the building is of unusually tight construction (see definition, next
page), the building must also be provided with air openings directly
to the outside, sized and located per Figure 3, Figure 4 or Figure 5.
2. Buildings of typical construction should provide adequate combustion
air from natural infiltration, so additional air openings to the building
are not required.
3. See Figure 2. Provide two openings through the interior wall, within
12 inches of the ceiling and the floor, sized per Figure 2.
Two openings — Air supply directly from outside ✷
1. Air openings must be directly through an outside wall, or into a space
that connects directly to the outside (such as a ventilated attic or crawl
space, for example).
2. See Figure 3 — Openings directly through an outside wall — provide
two openings within 12 inches of the ceiling and the floor, sized per
Figure 3.
3. See Figure 4 — Air supplied through vertical ducts — provide two
openings terminated within 12 inches of the ceiling and the floor, sized
per Figure 4.
4. See Figure 5 — Air supplied through horizontal ducts — provide
two openings within 12 inches of the floor and the ceiling, sized per
Figure 5.
Prepare boiler location — air openings
1e
Air openings must be provided
Combustion air and ventilation openings must comply the National Fuel
Gas Code ANSI Z223.1-latest edition, or applicable local building codes.
Canadian installations must comply with B149.1 or B149.2 Installation
Codes.
Provide adequate combustion and ventilation air to
assure proper combustion and reduce the risk of severe
personal injury, death or substantial property damage
caused by flue gas spillage and carbon monoxide
emissions.
Combustion air opening location and sizing
requirements depend on the clearances around
the boiler. Check the boiler placement compared to
Figure 1a, page 7.
If all clearances are at least equal to Figure 1a,
page 7, apply the sizing and placement of openings
given on pages 10 and 11.
If ANY clearance is less than Figure 1a, page 7,
you must provide air openings sized and located as
shown in Figure 1b,page 7. DO NOT apply the sizing
and location information shown on page 10 or 11.
✷
✷
✷
✷
✷

Part Number 550-101-009/0107 11
GOLD CGa Gas-Fired Water Boiler — Boiler Manual
Unusually tight construction
Unusually tight construction means (per ANSI Z223.1)
buildings in which:
a. Walls and ceilings exposed to the outside atmo-
sphere have a continuous water vapor retarder with
a rating of 1 perm or less with openings gasketed,
and . . .
b. Weather-stripping has been added on openable
windows and doors, and . . .
c. Caulking or sealants are applied to areas such as
joints around windows and door frames, between
sole plates and floors, between wall-ceiling joints,
between wall panels, at penetrations for plumbing,
electrical, and gas lines, and in other openings.
For such construction cases, if appliances use inside air
for combustion,provide air openings into the building
from outside. Size and locate these openings per the
appropriate case in Figure 3, 4 or 5 on page 10.
Motorized air dampers
If the air openings are fitted with motorized dampers,
electrically interlock the damper to:
• Prevent the boiler from firing if the damper is not
fully open.
• Shut the boiler down should the damper close dur-
ing boiler operation.
To accomplish this interlock, wire an isolated contact
(proving the damper open) in series with the thermo-
stat input to the boiler. The boiler will not start if this
contact is open, and will shut down should it open
during operation.
Exhaust fans and air movers
The appliance space must never be under a negative
pressure, even if the appliance(s) are installed as direct
vent. Always provide air openings sized not only to the
dimensions required for the firing rate of all appli-
ances, but also to handle the air movement rate of the
exhaust fans or air movers using air from the building
or space.
Single air opening option ✷
A single combustion air opening can be used in lieu of the two-opening
options on page 10, provided:
Clearances from boiler to walls
• The boiler must have clearances of at least those shown in Figure 1a,
page 7.
Opening must be directly to outside
• The opening must connect directly to the outdoors or to a space that
communicates directly to the outdoors (not to an interior space).
• The air can be provided through a direct opening or through a horizontal
or vertical duct.
Opening placement
• The top of the air opening must be within 12 inches of the ceiling.
Opening size
• The free area of the opening must be at least equal to the sum of the
area of all equipment vent connectors in the space, and . . .
• The free area of the opening must be at least 1 square inch per 3,000
Btu/hr input rating of all equipment located in the space.
FREE AREA of openings — the minimum areas
given in this manual are free area (equals the area,
length times width of opening, after deduction for
louver obstruction).
Use the free area information provided by the louver manufacturer.
When this information is not available, assume:
• Wood louvers — assume free area is 20% of total; so the actual area
of each opening with wood louvers would be 5 times the required
free area.
• Metal louvers — assume free area is 60% of actual area; so, for wood
louvers, the actual area of each opening must be 1.67 times the
required free area.
Exception for large spaces ✷
No combustion air openings are needed when the boiler (and other ap-
pliances) are installed in a space with a volume at least 50 cubic feet per
1,000 Btuh of all installed appliances, provided:
• the building must not have unusually tight construction (see defini-
tion, this page)
• all clearances around the boiler must must be no less than shown in
Figure 1a, page 7.
To determine if the space is large enough to qualify:
• Add the total input of all appliances in MBH (1,000’s of Btuh).
• Multiply this number times 50 to determine minimum room volume.
• Example: For a total input of 100 MBH (100,000 Btuh), minimum
volume is 50 x 100 = 5,000 cubic feet. At a ceiling height of 8 feet, the
space must have at least 5,000 ÷ 8 = 625 square feet (25 feet x 25 feet,
for instance).

GOLD CGa Gas-Fired Water Boiler — Boiler Manual
12 Part Number 550-101-009/0107
Prepare boiler — placement and setup
2a
Inspect orifices and burners
1. Remove front jacket door. Remove base access panel
(See Figure 32, item 4, page 62).
2. Check for correctly-sized manifold orifices. See
Table 2 below for sizing.(The orifice size is stamped
on the orifice spud barrel.)
Place boiler/crate near
position
1. Leave boiler in crate and on pallet until installa-
tion site is ready.
2. Move entire crate and pallet next to selected loca-
tion.
3. Remove crate. Leave boiler on pallet.
4. Remove boiler from pallet as follows:
a. Tilt left side of boiler up and place a board under
left legs.
b. Tilt boiler the other way and place a board under
right legs.
c. Slide boiler backwards off pallet and into posi-
tion.
Do not drop boiler or bump jacket
on floor or pallet. Damage to boiler
can result.
5. Check level.
a. Shim legs, if necessary.
b. Do not alter legs.
Orifice replacement procedure
(when required)
1. Remove access panel.
2. On gas manifold,mark location of main burner with
attached pilot assembly.
3. Remove main burner with attached pilot assembly
from manifold. Remove all remaining burners.
4. Remove and discard all main burner orifices in gas
manifold.
5. Apply a small amount of pipe dope to each of the
new orifices and install in the manifold. Make sure
the orifices are aligned correctly, not cross-threaded
in the manifold tappings.
Use only pipe dope compatible with
propane gas, even if boiler is to be
operated on natural gas. Failure to
comply could result in severe per-
sonal injury, death or substantial
property damage.
6. Reinstall main burner with attached pilot assembly
at location marked on gas manifold. Reinstall all
remaining burners.
7. Follow check-out procedure, Section 7, page 33.
Table 2 Manifold orifice sizing
Correctly-sized manifold orifices
must be used. Failure to do so will
result in severe personal injury,
death or substantial property dam-
age.
3. Level and straighten burners.
Burners must be properly seated in
slots in burner rest with their open-
ings face up. Main burner orifices
must inject down center of burner.
Failure to properly seat burners
will result in severe personal injury,
death or substantial property dam-
age.
4. Reinstall access panel.
Do not operate boiler without ac-
cess panel secured in place. Failure
to comply could cause momentary
flame rollout on ignition of main
flame, resulting in possible fire or
personal injury hazard.
Location Natural gas
U. S.
0-2,000 ft over 2,000 ft
2.00 mm (Note 1)
Canada 0-2,000 ft 2,000-4,500
2.00 mm 1.90 mm
Location Propane gas
U. S.
0-2,000 ft over 2,000 ft
1.30 mm (Note 1)
Canada 0-2,000 ft 2,000-4,500
1.30 mm 1.20 mm
Note 1: For elevations above 2,000 feet, contact your
local Weil-McLain sales office for details.

Part Number 550-101-009/0107 13
GOLD CGa Gas-Fired Water Boiler — Boiler Manual
Prepare boiler — pressure test
Hydrostatic pressure test
Pressure test boiler before attaching water or gas piping
or electrical supply (except as noted below).
Prepare boiler for test
1. Remove the shipping nipple (from CGa supply
tapping) and remove the boiler relief valve. Tempo-
rarily plug the relief valve tapping with a ¾” NPT
pipe plug.
2. Remove 1¼” nipple, reducing tee and drain valve
from accessory bag. Install in boiler return con-
nection as shown on page 3 or in Figure 34, item
3, page 64. Install circulator on either the return or
supply.
3. Remove 1¼” nipple, 1¼” tee, bushing and pres-
sure/temperature gauge from accessory bag. Pipe
to boiler supply connection as shown in Figure 34,
page 64. (Use pipe dope sparingly.)
4. Connect a hose to boiler drain valve, the other end
connected to a fresh water supply. Make sure hose
can also be used to drain boiler after test.
5. Connect a nipple and shutoff valve to system supply
connection on the 1¼” tee. This valve will be used
to bleed air during the fill. (Valve and nipple are
not included with boiler.)
6. Connect a nipple and shutoff valve to system
return connection (at circulator flange if circula-
tor installed on return). This valve will be used to
bleed air during the fill. (Valve and nipple are not
included with boiler.)
Fill and pressure test
1. Open the shutoff valves you installed on supply and
return connections.
2. Slowly open boiler drain valve and fresh water sup-
ply to fill boiler with water.
3. When water flows from shutoff valves, close boiler
drain valve.
Drain and remove fittings
1. Disconnect fill water hose from water source.
2. Drain boiler at drain valve or out hose, whichever
provides best access to drain. Remove hose after
draining if used to drain boiler.
3. Remove nipples and valves unless they will remain
for use in the system piping.
4. Remove plug from relief valve tapping. See Section 3
to replace relief valve.
Do not use petroleum-based clean-
ing or sealing compounds in boiler
system. Severe damage to boiler
will occur, resulting in substantial
property damage.
Leaks must be repaired at once.
Failure to do so can damage boiler,
resulting in substantial property
damage.
2b
4. Close shutoff valves.
5. Slowly reopen boiler drain valve until test pressure
of not more than 45 psi is reached on the pressure/
temperature gauge.
6. Test at no more than 45 psi for no more than 10
minutes.
Do not leave boiler unattended.
A cold water fill could expand and
cause excessive pressure, resulting
in severe personal injury, death or
substantial property damage.
7. Make sure constant gauge pressure has been main-
tained throughout test. Check for leaks. Repair if
found.

GOLD CGa Gas-Fired Water Boiler — Boiler Manual
14 Part Number 550-101-009/0107
Prepare boiler — draft hood & spill switch
Draft hood installation
1. Orient draft hood with spill switch mounting holes to front of boiler
as shown in Figure 7.
2. Secure draft hood to outlet at top of boiler with sheet metal screws.
3. Bottom of draft hood or “skirt” must have clearance dimension above
jacket top panel as indicated on draft hood.
Do not alter boiler draft hood or place any obstruction or
non-approved vent damper in breeching or vent system.
CSA certification will become void.Flue gas spillage and
carbon monoxide emissions will occur causing severe
personal injury or death.
Spill switch installation
1. Fasten spill switch to draft hood as shown in Figure 6
and Figure 7.
2. See Wiring diagram to connect wires:
a. Standing pilot boiler — see page 34.
b. Spark-ignited pilot boiler —
see pages 38 and 39.
Improper orientation of spill switch
may cause boiler to shut down. The
loss of heat can result in significant
damage due to freezing.
Prepare boiler — install vent piping
1. Connect from draft hood or vent damper outlet to chimney or vent
with same size vent connector.
2. Where possible, vertical venting to the outside from the draft hood or
vent damper outlet will offer best performance.
3. Where horizontal vent connector is used, slope upward at least ¼” per
lineal foot toward chimney or vent and support with hangers to prevent
sagging.
4. Breeching must not be connected to any portion of a mechanical draft
system that can operate under positive pressure.
Figure 7 Spill switch with wire harnessFigure 6 Install spill switch
2c
2d
Long horizontal vent connector,
excessive number of elbow or
tees, or other obstructions that
restrict the flow of combustion
gases should be avoided. Severe
personal injury, death or sub-
stantial property damage could
result.

Part Number 550-101-009/0107 15
GOLD CGa Gas-Fired Water Boiler — Boiler Manual
Prepare boiler — vent damper installation
4. Read and apply the harness plug warning label
(shown above) so that it is visible after installa-
tion.
5. Plug damper harness receptacle into damper harness
plug.
Bypassing (jumpering) vent damper
will cause flue products such as
carbon monoxide to escape into
the house. This will cause severe
personal injury or death.
After boiler has operated once, if ei-
ther end of harness is disconnected,
the system safety shutdown will oc-
cur. The boiler will not operate until
harness is reconnected.
Effikal or Field Controls damper
—Damper hold open switch must
be in Automatic Operation position
for system to operate properly.
Figure 8 Vent damper assemblies
These systems are used on gas-fired boilers with vent
dampers as shipped from factory. Boiler will not operate
without vent damper installed.
Only vent dampers listed in the Replacement parts list
on page 61 are certified for use with CGa boilers. Any
other vent damper installed could cause severe personal
injury or death.
Installation
1. Install vent damper horizontally or vertically as
shown in vent damper manufacturer’s instructions.
Vent damper must be installed so that it serves only
one boiler and so damper blade indicator is visible
to the user. See Figure 8.
2. Screws or rivets used to secure the vent damper to
the draft hood must not interfere with rotation of
the damper blade.
3. Install damper harness between damper actuator
and knockout in jacket top panel. Use strain relief
connectors and locknuts to secure both ends of
damper harness.
Keep wiring harness clear of all hot
surfaces.
2e
Damper blade
Standing pilot ignition systems— Refer to vent
manufacturer’s instructions to install plug (shipped
with damper) in damper hole. For standing pilot boil-
ers only, install plug with 3 /8” diameter hole in vent
damper hole.
Spark-ignited pilot systems— Refer to vent man-
ufacturer’s instructions to install plug (shipped with
damper) in damper hole.For spark-ignited pilot boilers
only, install plug with no hole in vent damper hole.
Minimum clearances
Provide a minimum of 6” between the vent damper and
any combustible material. (Provide a minimum of 36 "
between jacket top and combustible ceiling.)
Do not modify draft hood or vent damper, or make an-
other connection between draft hood and vent damper
or boiler except as noted below. This will void CSA
certification and will not be covered by Weil-McLain
warranty. Any changes will cause severe personal injury,
death or substantial property damage.

GOLD CGa Gas-Fired Water Boiler — Boiler Manual
16 Part Number 550-101-009/0107
Water piping — general information3a
Boiler model To
system
From
system
CGa-25 ¾" ¾"
CGa-3, 4, 5 1" 1"
CGa-6, 7 1 ¼" 1 ¼"
CGa-8 1 ½" 1 ½"
Note: The boiler supply and return connections, the return/
drain tee and the supply/gauge tee supplied with the
boiler are 1¼” NPT. One of the circulator flanges sup-
plied with the boiler is 1¼”. The other circulator flange
is the size of the recommended system piping shown
above.
General piping information
If installation is to comply with ASME or Canadian requirements, an ad-
ditional high temperature limit is needed. Install control in supply piping
between boiler and isolation valve. Set second control to minimum 20°F
above setpoint of first control. Maximum allowable setpoint is 240°F. See
page 34 or 38, for wiring.
A low water cutoff device is required when boiler is installed above ra-
diation level or by certain state or local codes or insurance companies. Use
low water cutoff designed for water installations. Electrode probe-type is
recommended. Purchase and install in tee in supply piping above boiler.
Use backflow check valve in cold water supply as required by local
codes.
Pressure/temperature gauge
Install pressure/temperature gauge in tee on supply piping (as shown in
drawing on page 3).
Relief valve
Install relief valve vertically in ¾” tapping on side of boiler. See Figure 9
or 10, page 17, and the tag attached to the relief valve for manufacturer’s
instructions.
System water piping
See Figure 9 (diaphragm-type or bladder-type expan-
sion tank) or Figure 10 (closed-type expansion tank),
and Table 3 below, for near-boiler and single-zone
systems designed for return water at least 130°F.
See pages 18-19 to complete multiple-zone piping or
pages 20-25 to complete piping for radiant heating
systems or converted gravity systems (large-volume
systems originally designed for circulation by natural
convection rather than a pump). See page 25 for boilers
used with refrigeration systems.
Chillers or air handling units:
Install boiler such that —
• Chilled medium, if used, is piped in parallel with
heating boiler. Use appropriate valves to prevent
chilled medium from entering boiler. Consult
I=B=R Installation and Piping Guides.
• If boiler is connected to heating coils located in
air handling units where they can be exposed to
refrigerated air, use flow control valves or other au-
tomatic means to prevent gravity circulation during
cooling cycle. Circulation of cold water through the
boiler could result in damage to the heat exchanger,
causing possible severe personal injury, death or
substantial property damage.
Circulator
The circulator is shipped loose (wiring pre-attached to
boiler) to allow you to locate it either in the return or
supply piping, as desired. See page 3 for a typical instal-
lation. Pipe the expansion tank to the suction side of the
circulator whenever possible. Install an air separator in
the supply piping. Connect the expansion tank to the air
separator only if the separator is on the suction side of
the circulator. Always install the system fill connection
at the same point as the expansion tank connection to
the system. Figures 9 and 10 show typical near-boiler
piping connections.
Table 3 Water pipe size (based on 20°F rise)
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 to eliminate
possibility of severe burns should the valve discharge.
• Discharge line must be as short as possible and be 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 floor drain where any discharge will be clearly
visible.
• The discharge line shall terminate plain, not threaded, with a mate-
rial serviceable for temperatures of 375°F or greater.
• Do not pipe the discharge to any place where freezing could
occur.
• No shutoff valve shall be installed between the relief valve and boiler,
or in the discharge line. Do not plug or place any obstruction in the
discharge line.
• Failure to comply with the above guidelines could result in failure of
the relief valve to operate, resulting in possibility of severe personal
injury, death or substantial property damage.
• Test the operation of the valve after filling and pressurizing system
by lifting the lever. Make sure the valve discharges freely. If the valve
fails to operate correctly, replace it with a new relief valve.

Part Number 550-101-009/0107 17
GOLD CGa Gas-Fired Water Boiler — Boiler Manual
Diaphragm-type or bladder-
type expansion tank (Figure 9)
1. Ensure expansion tank size will handle boiler and
system water volume and temperature. Tank must
be located in boiler return piping as close to boiler
as possible, before inlet side of circulator. See tank
manufacturer’s instructions for details.
2. Install an automatic air vent as shown.
Closed-type expansion tank
(Figure 10)
1. Ensure expansion tank size will handle boiler and
system water volume and temperature. See tank
manufacturer’s instructions for details.
2. Connect tank to ½” NPT tapping located behind
supply outlet, using ½” NPT piping. Pitch any
horizontal piping up towards tank 1 inch per 5 feet
of piping.
Undersized expansion tanks cause system water to be lost from relief valve and makeup water
to be added through fill valve. Eventual section failure can result.
Water piping — single-zone system
Figure 9 Diaphragm- or bladder-type expansion
tank — Single-zone system using dia-
phragm-type or bladder-type expansion
tank. See Table 3 for piping sizes.
Figure 10 Closed-type expansion tank — Single-
zone system using closed-type expan-
sion tank. See Table 3 for piping sizes.
3b
Use Figure 9 or Figure 10 only for single-zone systems designed for return water at least
130°F. For systems with low return water temperature possible, such as converted gravity
systems and radiant heating systems, refer to the special piping suggestions of pages 20-25.
Failure to prevent low return water temperature to the boiler could cause corrosion of the
boiler sections or burners, resulting in severe personal injury, death or substantial property
damage.

GOLD CGa Gas-Fired Water Boiler — Boiler Manual
18 Part Number 550-101-009/0107
Water piping — multiple zones
Piping multiple zones
Follow instructions on pages 16 and 17 to install near-
boiler or single-zone piping. (Also refer to Piping for
radiant heating systems or converted gravity sys-
tems, below, if applicable.)
See Figure 11 or Figure 12, page 19, to complete in-
stallation.
Zoning with circulators (Figure 11)
(return temp over 130°F)
1. Size each circulator to individual circuit require-
ments.
2. Do not install circulator on boiler (except for pri-
mary/secondary piping).
3. Install isolation (balancing) valves to adjust flow to
distribute heat to all zones.
4. Install and wire a separate relay for each zone cir-
culator.
Zoning with zone valves (Figure 12)
(return temp over 130°F)
1. Install isolation (balancing) valves to adjust flow to
distribute heat to all zones.
2. Provide a separate 24-volt transformer to power the
zone valves. Size the transformer to handle the total
rated load of all connected zone valves.
3c
Piping for radiant heating
systems or converted gravity
systems
Converted gravity (or steam) systems
Whenever possible, use the primary/secondary piping
shown in Figures 13 or 14 on page 21. This piping de-
sign allows changing boiler flow rate without affecting
primary circuit flow rate.
If Figures 13 or 14 cannot be used,use the boiler-bypass
piping shown in Figure 15 or Figure 16 on page 23.You
can also use the piping shown in Figure 17 on page 25
(system-bypass), if the reduced flow rate in the heating
system will not cause heat distribution problems.
Failure to prevent low return water
temperature to the boiler could
cause corrosion of the boiler sec-
tions or burners, resulting in severe
personal injury, death or substantial
property damage.
Radiant heating systems
Preferably, use primary/secondary piping, as shown
in Figures 13 or 14 on page 21. Alternatively, use the
method of either Figure 15 or Figure 16 on page 23.
Do not use the piping of Figure 17 (system-bypass),
because this method does not control radiant system
supply temperature.
If radiant system tubing has no oxygen barrier, a heat
exchanger must be used.
Radiant heating system piping should include a means of regulating the boiler return water
temperature and the system supply temperature (such as provided by an injection pumping
control). Boiler return water temperature will be adequately controlled using the methods
shown in this manual provided the system supply temperature is relatively constant.
DO NOT apply the methods in this manual if the system is equipped with an outdoor reset
control. Instead, provide controls and piping which can regulate the boiler return water
temperature at no less than 130°F regardless of system supply temperature. Contact your
Weil-McLain representative for suggested piping and control methods. Failure to prevent
cold return water temperature to the boiler could cause corrosion damage to the sections
or burners, resulting in possible severe personal injury, death or substantial property dam-
age.

Part Number 550-101-009/0107 19
GOLD CGa Gas-Fired Water Boiler — Boiler Manual
Figure 11 Zoning with circulators — return water
130°F or higher.
Figure 12 Zoning with zone valves — return water
130°F or higher.
1 Boiler isolation (balancing)
valves
2 Flow/check valve
3 System or zone circulator
5 Zone valve
6 Drain valve
9 Relief valve
10 Automatic air vent (with diaphragm-type expansion tank), or connect
to tank fitting (closed-type expansion tank). DO NOT use an automatic
air vent when using closed-type expansion tank. It would allow air to
leave the system, causing waterlogging of the expansion tank.
11 Fill valve
12 Diaphragm-type or bladder-type expansion tank, if used (For closed-
type expansion tank, pipe from top of air separator to tank fitting as in
Figure 10, page 17.)
13 Air separator and automatic vent, if used (Note that the fill valve must
always be connected to the expansion tank, regardless of location of
expansion tank circulator or air separator.
For systems with possible low return-water temperature (such as converted gravity systems,
radiant heating systems and heat pump systems), refer to the special piping suggestions of
Figures 13 – 17, as applies. Failure to prevent sustained low return water temperature to
the boiler could cause corrosion of the boiler sections, resulting in severe personal injury,
death or substantial property damage.
Water piping — multiple zones (continued)3c

GOLD CGa Gas-Fired Water Boiler — Boiler Manual
20 Part Number 550-101-009/0107
Failure to prevent low return water temperature to the boiler could cause corrosion of
the boiler sections or burners, resulting in severe personal injury, death or substantial
property damage.
Radiant heating system piping should include a means of regulating the boiler return
water temperature and the system supply temperature (such as provided by an injec-
tion pumping control).
Boiler return water temperature will be adequately controlled using the methods shown
in this manual provided the system supply temperature is relatively constant.
DO NOT apply the methods of this manual if the system is equipped with an outdoor
reset control. Instead, provide controls and piping which can regulate the boiler re-
turn water temperature at no less than 130°F regardless of system supply temperature.
Contact your Weil-McLain representative for suggested piping and control methods.
Failure to prevent cold return water temperature to the boiler could cause corrosion
damage to the sections or burners, resulting in possible severe personal injury, death or
substantial property damage.
Primary/secondary (preferred)
Bypass piping method
Primary/secondary bypass piping is preferred because
the flow rate and temperature drop in the heating
circuit(s) is determined only by the heating circuit
circulator(s). So adjustment of the bypass valves in
the boiler circuit will not cause a change in the heating
circuit rate and temperature distribution.
Figures 13 and 14, page 21, show suggested bypass
arrangements using primary/secondary bypass piping
(preferred) for low temperature systems such as radiant
heating systems or converted gravity systems. For
alternatives, see pages 22 through 25.
The bypass valves (items 7a and 7b) provide mixing of
hot boiler outlet water with cooler system return water
— set to assure a minimum return water temperature
(at least 130°F) to the boiler. Set the valves as explained
below.
Temperature gauges
Gauge 4a is suggested, but optional on any system.
Gauge 4b is optional on converted gravity systems,
but required on radiant heating systems — to display
3d
the water temperature being supplied to the radiant
tubing.
Gauge 8is required on all systems to assure the return
water temperature is accurately set for a minimum of
130°F. If this gauge is not available however, adjust the
valves such that the boiler-mounted temperature/pres-
sure gauge reads at least 150°F when the system return
water is cold (approximately 60°F water temperature).
Valve adjustment
(Figures 13 and 14 only)
1. Set the valves while the system is cool,setting for the
coldest expected water temperature (usually 60°F
since the system will often drop to room tempera-
ture between cycles).
2. Start with valve 7a fully closed and 7b fully open.
3. Gradually open valve 7a while closing valve 7b until
the temperature at gauge 8reads 130°F when gauge
4a reads 60°F.
4. Note that valve 7a regulates the amount of hot wa-
ter from the boiler supply which mixes with return
water.Valve 7b regulates the amount of system water
flowing through the boiler secondary loop.
Piping — low temperature systems