Weil-McLain WTGO Installation and operation manual

Part number 550-141-825/1211
This manual must only be used by a qualified heating installer/service technician. BEFORE
installing, read all instructions in this manual and all other information shipped with the
boiler. Perform steps in the order given. Failure to comply could result in severe personal
injury, death or substantial property damage.
• Installation
• Startup
• Maintenance
• Parts
Boiler Manual
Oil-Fired Water Boilers

Part number 550-141-825/1211
2
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
HOMEOWNER and SERVICE TECHNICIAN — read and follow completely.
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 damage.
Indicates special instructions on installation, operation or
maintenance that are important but not related to personal injury
or property damage.
Hazard definitions
When calling or writing about the boiler
Please have boiler model number and series from boiler rating label and CP number(s) from boiler jacket,
burner and controls. On page 30 of this manual is space to list CP number(s).
Packaged and non-packaged boilers
Packaged boilers, available only in sizes 2 through 6, are factory assembled, complete with block, jacket and
controls. Burner is shipped separately.
Non-packaged boilers, available in all sizes, 2 through 9, are shipped with block assembled, with jacket.
Controls, trim and burner shipped separately for field assembly.
Homeowner —
Read and follow all information on pages 1 through 7 ONLY.
Service technician —
Read and follow ALL information in the entire manual.
Failure to follow all instructions in proper order can cause severe personal injury, death or
substantial property damage.
Using this manual

Part number 550-141-825/1211 3
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
HOMEOWNER and SERVICE TECHNICIAN — read and follow completely.
Contents
Using this manual . . . . . . . . . . . . . . . . . . . . .2
When calling or writing about the boiler . . . . . . . .2
Packaged and non-packaged boilers. . . . . . . . . .2
Hazard denitions . . . . . . . . . . . . . . . . . . . . .2
Please read before proceeding . . . . . . . . . . . . . .4
Tips for water systems — . . . . . . . . . . . . . . .4
Routine maintenance schedule. . . . . . . . . . . . . .5
Beginning each heating season . . . . . . . . . . . .5
Daily during heating season . . . . . . . . . . . . . .5
Weekly during heating season . . . . . . . . . . . . .5
End of heating season . . . . . . . . . . . . . . . . .5
Boiler shutdown . . . . . . . . . . . . . . . . . . . .5
Operation. . . . . . . . . . . . . . . . . . . . . . . . . .6
WTGO (see Figure 1) . . . . . . . . . . . . . . . . .6
Troubleshooting . . . . . . . . . . . . . . . . . . . . . .7
Before installing boiler . . . . . . . . . . . . . . . . . .8
Installations must comply with . . . . . . . . . . . . .8
Before selecting boiler location. . . . . . . . . . . . .8
Provide clearances around boiler (see Figure 2). . . .8
Provide air for combustion and ventilation . . . . . . .9
Lay a foundation, if needed . . . . . . . . . . . . . .9
Install boiler — packaged boilers only . . . . . . . . . 10
Place boiler. . . . . . . . . . . . . . . . . . . . . . 10
Perform hydrostatic pressure test . . . . . . . . . . 10
Install boiler — non-packaged boilers only . . . . . . 12
Place boiler. . . . . . . . . . . . . . . . . . . . . . 12
Tankless heater, if used . . . . . . . . . . . . . . . 12
Perform hydrostatic pressure test . . . . . . . . . . 14
Install jacket (required on sizes 7 through 9 only) . .14
Install boiler controls . . . . . . . . . . . . . . . . .14
Install burner — all boilers . . . . . . . . . . . . . . . 15
Install burner (also refer to instructions
packed with burner) . . . . . . . . . . . . . . . . . 15
For P-WTGO and A-WTGO boiler . . . . . . . . . .15
Connect breeching . . . . . . . . . . . . . . . . . . . 16
General chimney requirements. . . . . . . . . . . . 16
Connect breeching . . . . . . . . . . . . . . . . . . 16
Connect water piping . . . . . . . . . . . . . . . . . . 18
General piping information . . . . . . . . . . . . . .18
Install piping: . . . . . . . . . . . . . . . . . . . . .18
DIAPHRAGM expansion tank (Figure 9) . . . . . . . 18
CLOSED expansion tank (Figure 10) . . . . . . . . 18
To connect WTGO boilers to
indirect-fired water heaters . . . . . . . . . . . . . . 18
Piping MULTIPLE ZONES . . . . . . . . . . . . . .20
Piping for systems requiring
temperatures below 140°F . . . . . . . . . . . . . .21
Use with refrigeration systems . . . . . . . . . . . . 22
Connect tankless heater piping . . . . . . . . . . . . 23
Connect wiring. . . . . . . . . . . . . . . . . . . . . . 24
General wiring requirements . . . . . . . . . . . . . 24
Junction box (furnished) . . . . . . . . . . . . . . .24
High temperature limit . . . . . . . . . . . . . . . . 24
3-Wire zone valve applications . . . . . . . . . . . . 24
Blocked vent shutoff switch . . . . . . . . . . . . . 27
Connect oil piping . . . . . . . . . . . . . . . . . . . . 28
General oil piping requirements . . . . . . . . . . . 28
Start-up. . . . . . . . . . . . . . . . . . . . . . . . . . 29
Fill the system . . . . . . . . . . . . . . . . . . . . 29
When using antifreeze . . . . . . . . . . . . . . . .29
To place in operation . . . . . . . . . . . . . . . . .29
Burner adjustments . . . . . . . . . . . . . . . . . 29
Check-out procedure . . . . . . . . . . . . . . . . . . 30
Check off steps as completed . . . . . . . . . . . . 30
Installation and service certificate . . . . . . . . . .30
Annual service check list . . . . . . . . . . . . . . . . 31
Controls requiring annual service . . . . . . . . . . 31
Detailed service procedures . . . . . . . . . . . . . . 32
Cleaning boiler flueways . . . . . . . . . . . . . . .32
General description of control operation . . . . . . .32
Handling ceramic ber and berglass materials . . . 33
Close clearance installation . . . . . . . . . . . . . . 34
Close clearance installation . . . . . . . . . . . . . 34
Replacement parts . . . . . . . . . . . . . . . . . . . 36
Dimensions . . . . . . . . . . . . . . . . . . . . . . . 41
Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Notes . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Part number 550-141-825/1211
4
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
HOMEOWNER and SERVICE TECHNICIAN — read and follow completely.
Follow instructions below to prevent severe personal
injury, death or substantial property damage:
• To avoid electric shock, disconnect electrical supply to burner
service switch and additional external switches before perform-
ing service.
• To avoid severe burns, allow boiler to cool before performing
service.
• Do not block flow of combustion or ventilation air to boiler.
• Boiler must be connected to a flue with sufficient draft at all times
to assure proper operation.
• Do not use this boiler if any part has been under water. Electrical
and mechanical failures may cause electric shock and fire risks.
Immediately call a qualified service technician to inspect chimney
or vent, boiler and burner. Have the boiler flueways cleaned and
have the following replaced:
• all electrical and mechanical controls
• electrical wiring
• oil burner and controls
• insulation and chamber lining
Tips for water systems —
• Check boiler and system piping for leaks. Continual makeup water
will reduce boiler life. Minerals can build up in sections, reduc-
ing heat transfer and causing cast iron to overheat, resulting in
section failure.
Failure to maintain recommended pH and repair leaks
can cause section iron corrosion, leading to section
failure and leaks. Do not use petroleum-based sealing
or stop-leak compounds in boiler systems. Damage to
system components can result, causing property damage.
• Boiler water pH 7.0 to 8.5 is recommended. For pH conditions
outside 7.0 to 8.5 range or unusually hard water areas (above 7
grains hardness), consult local water treatment company.
• When using antifreeze:
Use antifreeze especially made for hydronic systems. Inhibited
propylene glycol is recommended.
Do not use automotive, ethylene glycol, undiluted or
petroleum-based antifreeze.Severe personal injury, death
or substantial property damage can result.
50% solution provides protection to about –30°F.
Local codes may require back-flow preventer or actual discon-
nect from city water supply.
Determine quantity according to system water content. Boiler
water content is listed on back cover of Boiler Manual.
Percent of solution will affect sizing of heat distribution units,
circulator and expansion tank.
Follow antifreeze manufacturer’s instructions.
Do not add cold water to hot boiler. Thermal shock can cause
sections to crack.
Please read before proceeding
Homeowner —
• For homeowner or person responsible for
simple start-up and routine maintenance of
the system
• Instructions on pages 1 through page 7 must
be followed to assure proper operation of your
boiler. See page 7 for a list of common prob-
lems and possible corrections. In addition, it
is your responsibility to:
• Have boiler and burner installed by a quali-
fied installer.
• Have boiler and burner serviced annually
by a qualified service technician.
• Review and understand start-up and rou-
tine maintenance procedures with quali-
fied service technician.
• Perform routine maintenance as described
on page 5.
Service technician —
• For a qualified service technician who has the
necessary equipment to check the boiler and
system performance, and is responsible for
start-up and service of boiler and system.
• All instructions in this manual must be fol-
lowed to assure proper operation of this boiler.
• Annually service boiler and burner to assure
proper operation. See page 31 for service
record.
• Review and explain start-up and routine main-
tenance procedures with homeowner.
Follow instructions below to prevent
severe personal injury, death or sub-
stantial property damage:
• Do not use crankcase drainings or any oil
containing gasoline. See burner manual for
proper fuel oil.
• Do not attempt to start burner when excess
oil has accumulated in combustion chamber,
when unit is full of vapor, or when combustion
chamber is very hot.
• Do not start burner unless collector hood, flue
cap, jacket cap, breeching and burner mount-
ing door are secured in place.
• Never burn garbage or paper in the boiler.
Never leave combustible material around
boiler.
• DO NOT TAMPER WITH UNIT OR CON-
TROLS. Always follow specific instructions
when starting up boiler or performing routine
maintenance or service.

Part number 550-141-825/1211 5
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
HOMEOWNER and SERVICE TECHNICIAN — read and follow completely.
Routine maintenance schedule
Beginning
each heating season Call a qualified service technician to perform annual service.
Daily
during heating season
Check that boiler area is free from combustible materials, gasoline
and other flammable vapors and liquids.
Weekly
during heating season
Check for and remove any obstructions to flow of combustion or
ventilation air to boiler.
Check that breeching is attached between boiler and chimney. If
breeching is loose or damaged, immediately turn off switch on
boiler and call service technician to repair.
Check for oil leaks in oil piping and around burner. If found, im-
mediately call qualified service technician to correct situation.
Check for water leaks in boiler and piping; also check for leaks
around tankless heater plate, if installed. If found, immediately call
service technician to repair.
End
of heating season
If tankless heater is installed, boiler will continue to operate. Check
for the following:
• All daily and weekly instructions listed on this page must be fol-
lowed.
• Burner motor may have to be oiled. Some motors are permanently
lubricated and do not need additional oil. Check for oiling in-
structions on burner or motor.
Boiler
shutdown
Do not drain boiler unless exposure to freezing temperatures will
occur.
Always keep manual fuel supply shut off if burner is shut down for
an extended period of time.
• Turn off switch at boiler and any external switch to boiler.
• Close fuel valves.
• Turn off water feed valve.
• Cover burner to protect from dust and dampness.

Part number 550-141-825/1211
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GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
HOMEOWNER and SERVICE TECHNICIAN — read and follow completely.
Operation
WTGO (see Figure 1)
1. If burner does not fire, check for:
• Service switch on boiler or additional switches turned off.
• Fuses or breaker switch tripped.
• Thermostat set below room temperature.
• Fuel valves turned off.
• Not enough oil in tank to supply burner.
Figure 1 WTGO Boilers
2. Correct problems found in step #1. If burner does not fire,
press reset button on burner primary control only once.
Repeated presses will deposit oil in combustion chamber.
Burner must never be fired when oil is in combus-
tion chamber. Immediately call qualified service
technician.
3. If burner still does not fire, call qualified service technician.
1 Burner disconnect plug
2 Service switch on boiler
3 Water relief valve
4 Temperature-pressure gauge
5 Circulator
6 Combination limit control,
tankless heater control and
low water cut-off (located in
tankless heater plate)
7 Reset button on burner
primary control
8 Burner primary control

Part number 550-141-825/1211 7
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
HOMEOWNER and SERVICE TECHNICIAN — read and follow completely.
Common Problems Common Causes Possible Corrections
Rapid cycling — burner
turns on and off frequently.
Thermostat installed where
drafts or heat affect reading.
Locate thermostat on inner wall away from heat sources or cool drafts.
Heat anticipator in thermo-
stat adjusted incorrectly.
Adjust heat anticipator to match current draw. Refer to boiler wiring
diagram.
Incorrect limit setting. Have qualified service technician increase limit setting to decrease
cycling. Maximum setting 220° F.
Need to frequently add
makeup water.
Leaks in boiler or piping. Have qualified service technician repair leaks at once to avoid constant
use of makeup water.
Popping or percolating
noise heard in boiler.
Mineral deposits in sections
due to constant use of make-
up water, or incorrect pH.
Have qualified service technician de-lime boiler, repair leaks at once
to avoid constant use of makeup water and check pH (between 7.0
and 8.5).
Black water condition. Oxygen corrosion due to
leaks in piping.
Have qualified service technician repair leaks at once to avoid constant
use of makeup water and check pH (between 7.0 and 8.5).
Frequent release of water
through relief valve.
Expansion tank sized too
small or water-logged.
Have qualified service technician check expansion tank operation.
Metal flakes found in
flueway.
Contaminated combustion
air supply.
Remove sources of hydrocarbons in or near boiler area. (Bleaches,
cleaners, chemicals, sprays, fabric softeners, paint remover, etc.)
Condensation of combustion
gases.
Have qualified service technician check boiler operation.
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. Have qualified service technician check for leaks in boiler or piping
at once.
High limit set too low. Have qualified service technician adjust limit to higher setting.
Domestic water from
tankless heater is hot then
suddenly turns cold.
OR
Domestic water from
tankless heater is always
lukewarm.
Mineral deposits insulate
internal waterways of heater.
Have qualified service technician delime or replace coil.
Boiler stop-leak compound
has been added to boiler wa-
ter and is insulating outside
of coil.
Have qualified service technician remove and clean coil and drain,
and flush boiler to remove stop-leak.
Incorrect mixing valve setting
for tankless heater.
Have qualified service technician adjust mixing valve setting.
Domestic flow rate too high. Have qualified service technician install flow check valve set to rating
of tankless heater.
Incorrect setting on tankless
heater control.
Have qualified service technician raise tankless control setting. Adjust
differential on tankless control to lower setting.
Troubleshooting
Homeowners — The problems and corrections below represent common situations that can occur. There may be
others not listed below. It is important always to contact a qualified service technician if you have any questions
about the operation of your boiler or system.

Part number 550-141-825/1211
8
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Before installing boiler
Homeowner — STOP! The procedures and information on this and following pages are intended only for a quali-
fied service technician who has the necessary equipment to inspect and adjust boiler and burner. A homeowner
should never attempt these procedures. The service technician must also read pages 1 through 7 before proceeding.
Top View
Walls
Wall
Figure 2 Recommended service clearances
Left side
A Provide 6" minimum clearance for service, provide 12"
minimum clearance for burner door swing.
B Minimum clearance from vent pipe to combustible mate-
rial: 6" for type “L” double-wall vent, 9" for single-wall
vent.
Failure to keep boiler area clear and free of combustible materials, gasoline and other flammable liquids and vapors
can result in severe personal injury, death or substantial property damage.
Installations must comply with
• United States
• State and local plumbing, heating and electrical codes.
• National codes where applicable.
• Canada
• Canadian Standards Association, CSA B139, Installation Code for
Oil-Burning Equipment.
• CSA C22.1 Canadian Electrical Code Part One.
• Applicable local or provincial codes.
Before selecting boiler location
• Check for nearby connections to:
• System water piping.
• Chimney. See page 16. Boiler can be top or back vented.
• Combustion and ventilation air supply. See page 9.
• Oil supply. See page 28 for oil line routing.
• Electrical power.
• Check area around boiler. Remove any combustible materials, gasoline
and other flammable liquids.
Provide clearances around boiler
(see Figure 2)
Jacket cap must be in place on boiler to
avoid requiring an 9" minimum clearance
from back or top of boiler to combustible
material.
• MINIMUM clearances from vent pipe to combus-
tible material:
• 6 inches — Type “L” double-wall vent*
• 9 inches — Single-wall vent
Flue pipe clearances must take precedence
over jacket clearances.
• Recommended SERVICE clearances:
• 24 inches — Front and top
• 6 inches — Left side, back and right side
• 12 inches — Right side for burner door swing
radius
• Specialclose clearances(alcove, closet,undercounters,
etc.) — see Appendix, page 34.
Ceiling
Wall
BB
B
24"
24"
A
A
A
Floor

Part number 550-141-825/1211 9
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Before installing boiler (continued)
Boiler
model
Length
inches
Width
inches
Min.
height
inches
WTGO-2 17 22 2
WTGO-3 17 22 2
WTGO-4 20 22 2
WTGO-5 20 22 2
WTGO-6 23 22 2
WTGO-7 26 22 2
WTGO-8 29 22 2
WTGO-9 32 22 2
Table 1 Boiler foundation sizes
Provide air for combustion and ventilation
Do not install exhaust fan in boiler room.
Adequate combustion and ventilation air:
• Assures proper combustion.
• Reduces risk of severe personal injury or death from possible flue gas
leakage and carbon monoxide emissions.
Older buildings with single-pane windows, minimal weather-stripping and
no vapor barrier often provide enough natural infiltration and ventilation
without dedicated openings.
New construction or remodeled buildings are most often built tighter.
Windows and doors are weather-stripped, vapor barriers are used and
openings in walls are caulked.As a result,such tight construction is unlikely
to allow proper natural air infiltration and ventilation.
Follow state, provincial or local codes when sizing adequate combustion and
ventilation air openings. In absence of codes, use the following guidelines
when boiler is in a confined room (defined by NFPA 31 as less than 7200
cubic feet per 1 GPH input of all appliances in area. A room 8 ft. high x
33.5 ft. x 33.5 ft. is 7200 cu. ft.):
• Provide two permanent openings — one within 12 inches of ceiling,
one within 12 inches of floor. Minimum height or length dimension
of each rectangular opening should be at least 3 inches.
• When inside air is used — each opening must freely connect with areas
having adequate infiltration from outside. Each opening should be at
least 140 sq. in. per 1 GPH input (1 sq. in. per 1000 Btu input) of all
fuel-burning appliances plus requirements for any equipment that can
pull air from room (including clothes dryer and fireplace).
• When outside air is used — connect each opening directly or by ducts
to the outdoors or to crawl or attic space that freely connects with
outdoors. Size per below:
• Through outside wall or vertical ducts — at least 35 sq. in. per
1 GPH input (1 sq. in. per 4000 Btu input) of all fuel-burning
appliances plus requirements for any equipment that can pull air
from room (including clothes dryer and fireplace).
• Through horizontal ducts — at least 70 sq. in. per 1 GPH boiler
input (1 sq. in. per 2000 Btu input) of all fuel-burning appliances
plus requirements for any equipment that can pull air from room
(including clothes dryer and fireplace).
• Where ducts are used, they should have same cross-sectional area as
free area of openings to which they connect. Compensate for louver,
grille or screen blockage when calculating free air openings. Refer
to their manufacturer’s instructions for details. If unknown, use:
• Wood louvers, which provide 20-25% free air.
• Metal louvers or grilles, which provide 60-75% free air.
Lock louvers in open position or interlock with equipment to prove open
before boiler operation.
Lay a foundation, if needed
Boiler may be installed on non-carpeted combustible
flooring.
For residential garage installation, install boiler so
burner is at least 18 inches above floor to avoid contact
with gasoline fumes.
A level concrete or masonry foundation is required
when:
• Floor could possibly become flooded.
• Non-level conditions exist.
Solid concrete blocks can be used to create a pad.

Part number 550-141-825/1211
10
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Install boiler — packaged boilers only
Place boiler
1. Remove circulator strapped to pallet.
Circulator will be damaged if not removed before
boiler is lifted from pallet.
2. Remove boiler from pallet.
Do not drop boiler or bump jacket on floor or
pallet. Damage to boiler can result.
Smaller sized boilers may be top heavy. Use caution
when handling to avoid minor personal injury or
property damage.
3. Boiler is shipped for back flue outlet. To change to top flue
outlet (see Figure 3, page 11):
a. Remove jacket cap on top of boiler.
b. Loosen two screws holding flue cap strap to collector
hood. Remove strap and flue cap from opening. Re-
tighten screws.
c. Check rope placement inside flue cap.
(Read under step #6).
d. Loosen two screws on back flue outlet. Set flue cap on
outlet. Install strap by engaging slots in screws. Tighten
screws. Make sure cap is securely installed.
e. Snap jacket cap in back outlet opening.
Jacket cap must be in place on boiler to avoid re-
quiring an 18” minimum clearance from back of
boiler to combustible material.
4. Check level. Shim legs, if needed.
5. Check for secure placement of insulation on target wall,
chamber floor and burner door.
6. Visually check:
a. Flue collector hood seal.
b. Burner mounting door seal.
Obtain gas-tight seal to prevent possible flue gas
leakage and carbon monoxide emissions, which
can lead to severe personal injury or death.
Perform hydrostatic pressure test
1. Remove relief valve installed in boiler.
2. Install air vent in “N” tapping on top boiler.
3. Plug supply and return tappings.
4. Drain valve is already factory-installed.
5. Fill boiler. Vent all air. Pressure test boiler at 1½ times work-
ing pressure.
Do not leave boiler unattended.Cold water fill can
expand and damage cast iron, resulting in severe
personal injury, death or substantial property dam-
age.
6. Check for maintained gauge pressure for more than 10 min-
utes. Visually check for leaks if gauge pressure drops.
7. Drain boiler. Repair leaks if found.
Do not use petroleum-based sealing compounds
to repair leaks.Damage to system components can
result, causing property damage.
8. Retest boiler after repairing leaks.
9. Remove air vent and plugs. Reinstall relief valve.

Part number 550-141-825/1211 11
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Instructions for packaged boilers are continued on page 15.
Install boiler — packaged boilers only (continued)
Figure 3 Change from back flue outlet to top flue outlet (optional)

Part number 550-141-825/1211
12
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Install boiler — non-packaged boilers only
Fiberglass wool and ceramic fiber materials are possible cancer
hazards. See warning on page 33.
Place boiler
1. Non-Packaged WTGO-3 through 6 — position on site.
Smaller sized boilers may be top heavy. Use caution when
handling to avoid minor personal injury or property damage.
a. Boiler is shipped for back flue outlet. To change to top flue outlet
(see Figure 4, page 13):
• Loosen two screws holding flue cap strap to collector hood.
Remove strap and flue cap from opening. Re-tighten screws.
• Check rope placement inside flue cap. (Read under
Step #3.)
• Loosen two screws on back flue outlet. Set flue cap on outlet.
Install strap by engaging slots in screws. Tighten screws. Make
sure cap is securely installed.
2. Non-Packaged WTGO-7, 8 & 9 — split the assembled block for easier
handling (see Figure 4):
a. Open burner mounting door and, using utility knife, slit floor
insulation at joint to be separated.
b. Remove 5½" draw rod and the longest draw rod from each side.
Pull block apart. Save draw rods, nuts, washers and sealing rings
for reassembly.
c. Move divided block to location.
d. Clean port openings with clean rag.
Do not use petroleum-based compounds to clean openings.
Damage to system components can result, causing property
damage.
e. Place rings in port openings. If ring slips out of groove, stretch ring
gently for several seconds, then place in groove.
f. Position sections so aligning lugs fit into sockets of next section.
Make sure sealing rope is in good condition and in position.
g. Oil threads on draw rods. Install washer and nut on end to be
tightened. Use nut only on other end.
h. With wrench at washer/nut end, uniformly tighten nuts starting
with 5½" rod at large port, 5½" rod at small port, bottom long rod
and finally top long rod.
i. Torque on both 5½" rods and bottom long rod should be 50–
60 ft-lbs; long top rod should be 20–25 ft-lbs. Do not back-off nuts.
j. Metal-to-metal contact should be made around port openings. If
gap does exist, it should be less than .020”. Check with feeler gauge.
k. If gap around port openings exceeds .020”, check for dirt on port
openings, sockets or misaligned lugs. If corrections are made and
gap still exists, contact your Weil-McLain distributor or sales office
before continuing installation.
3. Non-Packaged WTGO-7, 8 & 9 — install flue col-
lector hood (see Figure 4, page 13):
Obtain gas-tight seal to prevent possible
flue gas leakage and carbon monoxide
emissions, leading to severe personal
injury or death.
a. Thread tinnerman clip on screw so that clip
fits snugly in notch of hold-down lug. Screw
must not turn.
b. Remove paper on sealing rope. Starting at back
section near flue collar, position sealing rope
around top of block with adhesive side to sec-
tions. Do not stretch rope. Make sure rope ends
meet. Trim excess rope.
c. Position flue collector hood on top of boiler
sections and over screws and clips as shown in
Figure 4.
d. Install washers and nuts.Tighten nuts until col-
lector hood makes contact with tinnerman clip.
e. Back flue outlet boiler — Position flue cap
and strap over opening in flue collector hood.
Make sure rope in cap is in place and in good
condition. Tighten strap to hood with screws
provided.
Top flue outlet boiler — Position flue cap and
strap over opening in back section.
f. Make sure rope in cap is in place and in good
condition. Tighten strap to boiler with screws
provided in section. Install remaining screws in
holes in flue collector hood.
Tankless heater, if used
1. Remove tankless heater cover plate and gasket.
2. Install new gasket and tankless heater over studs
around opening. Secure with 3/8" nuts, tightening
until metal-to-metal contact is made (20–25 ft-lbs).

Part number 550-141-825/1211 13
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Install boiler — non-packaged boilers only (continued)
Figure 4 Change from back flue outlet to top flue outlet (optional)
Sealing
rope in
groove
inside cap
Flue
cap
Flue cap
strap
Flue
collector
hood
Sealing
rope with
adhesive
tape
Separate
block here
for easier
handling
Nut
Washer
Tinnerman
clip
Screw
Hold-down
lug

Part number 550-141-825/1211
14
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Install boiler — non-packaged boilers only (continued)
Location Size Function
B1 1½" Return piping
B2 1½" Alternate return piping for
A/B WTGO
C ¾” Supply piping
E3 ¼" Pressure-temperature
gauge
H ¾" Drain valve
L ¾" High limit control
(in tankless heater cover
plate)
N ½" Air vent or expansion tank
piping
R1 ¾" Relief valve
Table 2 Control tappings Figure 5 Control tapping locations
Front section
E3
R1
C
L
B1 H
N
B2
Back section
Perform hydrostatic pressure test
1. Refer to Control Tapping Table 2 and Figure 5 to install:
a. Boiler drain.
b. Water pressure gauge (test only). Be sure gauge can
handle test pressure.
c. Air vent in upper “N” tapping.
d. Plugs in remaining tappings.
2. Fill boiler. Vent all air. Pressure test boiler at 1½ times work-
ing pressure. For boilers split and reassembled, test between
75 and 85 psig.
Do not leave boiler unattended. Cold water fill
could expand and damage cast iron, resulting in
severe personal injury, death or substantial prop-
erty damage.
3. Check for maintained gauge pressure for more than 10 min-
utes. Visually check for leaks if gauge pressure drops.
4. Drain boiler. Repair leaks if found.
Do not use petroleum-based compounds to repair
leaks. Damage to system components can result,
causing property damage.
5. Re-test boiler after repairing leaks.
6. Remove pressure gauge, air vent and plugs from tappings
used for controls.
7. Visually check:
a. Sealing rope placement
b. Metal-to-metal contact around port openings.
c. Flue collector hood seal.
d. Burner mounting door seal.
Obtain gas-tight seal to prevent possible flue gas
leakage and carbon monoxide emissions, which
can lead to severe personal injury or death.
Install jacket
(required on sizes 7 through 9 only)
Before installing jacket, remove burner mounting door. See jacket
instructions for details.
Install boiler controls
See Control tapping (Table 2), Figure 5, and Figure 6 to install
controls.
1. Install tankless heater control if tankless heater is used. If
not furnished, use operating control with maximum 10°F
differential.
2. Install limit control. If not furnished, use high limit with
maximum 220°F setting.
3. Affix CP number label(s) on jacket front panel.

Part number 550-141-825/1211 15
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Install burner
(also refer to instructions packed with
burner)
Use only burners specified for use on
Weil-McLain GOLD oil boilers. DO
NOT use burners specified for use on
Weil-McLain Model 68 boilers. Contact
individual burner manufacturers for
proper burner selections.
Install burner — all boilers
Figure 6 Water boiler controls
Relief
valve
Water
pressure-temperature
gauge
Combination
Limit control
and low water
cut-off
Drain valve
Circulator
For P-WTGO and A-WTGO boiler
1. Secure universal mounting flange and gasket to burner mounting door.
Use three bolts provided.
2. Secure burner on flange with three bolts.
3. Position burner so end of air tube is level to 1½° tilt downward. Open
door to verify burner position. End of air tube should be flush to ¼"
recessed from inside wall of burner door refractory. Check for secure
placement of insulation on target wall, chamber floor and burner
mounting door. Securely close door with nut.

Part number 550-141-825/1211
16
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Connect breeching
Boiler
model
number
Minimum
breeching
diameter
(Note 3)
Minimum I=B=R
chimney size Minimum
chimney
height
Rect. Round
WTGO-3 5" 8" x 8"
(Note 1) 6" 15'
WTGO-4 6"
WTGO-5 6"
8" x 8"
(Note 1) 7" 15'WTGO-6
7"
WTGO-7
WTGO-8
7" 8" x 12"
(Note 2) 7" 20'
WTGO-9
Note 1 6 ¾” x 6 ¾” inside liner
Note 2 6 ½” x 10 ½” inside liner
Note 3 Flue collar on boiler is 7” diameter
Table 3 Minimum chimney sizes
General chimney requirements
• Designed for natural draft firing. Connect boiler to vertical chim-
ney.
Insufficient draft can cause flue gas leakage and carbon
monoxide emissions, which will lead to severe personal
injury or death.
• Use vent material approved by local codes for oil-fired burners. In
their absence, refer to:
• NFPA 31, Installation of Oil-Burning Equipment.
• NFPA 211, Standard for Chimneys, Fireplaces,Vents and Solid Fuel
Burning Appliances.
• In Canada, refer to CSA B139, Installation Code for Oil-
Burning Equipment.
• NFPA 211 requires chimney to be lined before connected to boiler.
Inspect existing chimney before installing new boiler.
Failure to do any of the following will result in severe
personal injury or death:
• Clean chimney, including removal of blockage.
• Repair or replace damaged pipe or liner.
• Repair mortar and joints.
To prevent downdrafts, extend chimney at least 3 feet above highest
point where it passes through roof and 2 feet higher than any portion
of building within 10 feet. Increase chimney cross-sectional area and
height at least 4% per 1,000 feet above sea level.
• Minimum clearances from vent pipe to combustible material:
Type “L” double-wall vent — 6 inches
Single-wall vent — 9 inches
• Minimum chimney sizes should be used.
Oversized chimneys, outside masonry chimneys and/or
de-rated inputs can result in condensation in chimney.
Connect breeching
Long horizontal breechings, excessive numbers of tees
and elbows or other obstructions restricting combustion
gas flow can result in possibility of condensation, flue gas
leakage and carbon monoxide emissions, which can lead
to severe personal injury or death.
1. Install 2 flue pipe brackets.
2. Connect full-sized breeching when possible. See Minimum Chim-
ney Size Table.
Back outlet — see Figure 7, page 17.
Top outlet — see Figure 8, page 17.
3. Connection must be made above bottom of chimney to avoid
blockage. Breeching must not enter chimney far enough to cause
obstruction. Use thimble or slip joint where breeching enters
chimney to allow removal for cleaning.
4. When burner and boiler are properly installed, draft
overfire will be approximately -0.01" to -0.02" W.C.
Install barometric control in breeching, per control
manufacturer’s instructions, when excess draft needs
to be relieved or to comply with applicable codes and
regulations. Use draft gauge to adjust proper opening.
5. An induced draft fan for the chimney may be neces-
sary if:
• Excessive resistance to flow of combustion gases
can be expected.
• Cross-sectional area of chimney is smaller than
minimum recommended.
• Chimney height is less than recommended.
Seal all vent joints. Interlock burner with fan
operation.

Part number 550-141-825/1211 17
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Figure 7 Back outlet breeching connection
Figure 8 Top outlet breeching connection
Typical location for
barometric control
(Also see control
manufacturer’s
instructions)
Flue pipe
bracket
(One on each
side of pipe)
Typical location for
barometric control
(Also see control
manufacturer’s
instructions)
Flue pipe bracket
(One on each side of pipe)
Connect breeching (continued)

Part number 550-141-825/1211
18
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Connect water piping
Boiler model
number To system From system
WTGO-3 1¼" 1¼"
WTGO-4 1¼" 1¼"
WTGO-5 1½" 1½"
WTGO-6 1½" 1½"
WTGO-7 1½" 1½"
WTGO-8 2" 2"
WTGO-9 2" 2"
* All piping sizes based on 20°F
temperature rise through boiler.
Table 4 Water piping sizes
General piping information
• All packaged WTGO boilers are shipped with an installed combination
temperature limit control/low water cut-off.
• If installation is to comply with ASME or Canadian requirements, an
additional high temperature limit is needed. Install control in supply
piping between boiler and isolation valve. Set control to a minimum
of 20°F above set point of combination control. Maximum allowable
set point is 220°F. Wire control as shown on wiring diagram.
• Use backflow check valve in cold water supply as required by local codes.
Install piping:
• See Figure 9 or Figure 10, page 19 and Water Piping Size Table 4 for
near-boiler piping and single-zone piping. See page 20 to complete
multiple-zone piping or page 21 to complete piping for systems oper-
ating below 140°F.
• For multiple-boiler piping, refer to Weil-McLain’s “Primary/Secondary
Piping Guide.”
• Install relief valve vertically in “R1” tapping on front of boiler. See
Figure 9 or Figure 10 and also refer to tag attached to relief valve for
manufacturer’s instructions.
Pipe relief valve discharge line near floor close to floor drain
to eliminate potential of severe burns. Do not pipe to any
area where freezing could occur. Do not plug, valve or place
any obstruction in discharge line.
DIAPHRAGM expansion tank
(Figure 9)
• Make sure expansion tank size will handle boiler and system water
volume and temperature. Tank must be located near boiler before inlet
to circulator. See tank manufacturer’s instructions for details.
Undersized expansion tanks cause system water to be lost
from relief valve and makeup water added through fill valve.
Eventual section failure can result.
• Install automatic air vent in “N” tapping as shown in Figure 9.
CLOSED expansion tank
(Figure 10)
• Ensure expansion tank size will handle boiler and system water volume
and temperature.
• Undersized expansion tanks cause system water to be lost from relief
valve and makeup water added through fill valve. Eventual section
failure can result.
• Connect tank from“N”tapping shown in Figure 10
to expansion tank. Use ½" NPT piping. Pitch any
horizontal piping up towards tank 1 inch per 5
feet of piping.
To connect WTGO boilers to
indirect-fired water heaters
• Install and wire per water heater manual provided
with water heater.
• If boiler has a tankless heater installed:
• Remove tankless heater and install cover plate.
OR
• Leave tankless heater installed. Drain coil and re-
move piping. Do not plug holes in tankless heater
front plate.

Part number 550-141-825/1211 19
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Connect water piping (continued)
Figure 9 Piping with DIAPHRAGM expansion tank
Figure 10 Piping with CLOSED expansion tank
Isolation
valve
From
system
Isolation valve
Cold water fill
To system
“C” tapping
“N” tapping
“B1” tapping
Relief
valve
Circulator
Closed type expansion tank
Circulator
(Alternate circulator location)
Isolation
valve
Circulator
Automatic
air vent
Relief
valve
To diaphragm
expansion tank
and fittings
From
system
To system
“C” tapping
“N” tapping
Isolation
valve
Cold water
fill
“B1” tapping
Circulator
(Alternate circulator location)

Part number 550-141-825/1211
20
GOLD WTGO OIL-FIRED NATURAL DRAFT WATER BOILER — SERIES 3 — Boiler Manual
SERVICE TECHNICIAN ONLY — read and follow completely.
Piping MULTIPLE ZONES
Follow instructions on page 18 and page 19 to install
piping near boiler.
See Figure 11 or Figure 12 to complete installation.
Zoning with circulators:
1. Size each circulator to individual circuit require-
ments.
2. Remove circulator (when furnished as standard
equipment).
3. Install balancing valves to adjust flow to distribute
heat to all zones.
4. Separate relay is required for each circulator.
Zoning with zone valves:
1. Install balancing valves to adjust flow to distribute
heat to all zones.
2. Separate transformer is required to power zone
valves. Refer to “Weil-McLain Zone Valve Wiring
Guide” for details.
Zone 2
Zone 1
5
1
2
1
3
Connect water piping (continued)
Figure 11 Multiple zoning with CIRCULATORS
Zone 2
Zone 1
4
5
1
1
Legend
1 Isolation valve
2 Flow control valve
3 Circulator
4 Zone valve
5 Drain valve
Figure 12 Multiple zoning with ZONE VALVES