Weil-McLain WTGO Series User manual

WTGO SERIES 3 OIL-FIRED NATURAL DRAFT WATER BOILER
This Manual
Includes:
Installation
Start-Up
Boiler Parts
Installer: •Make sure this is the correct manual for the boiler. Verify boiler model on
rating label.
•Leave all documentation received with boiler and burner with unit for
future reference.
User: Boiler and burner must be installed and serviced by qualified service technician.
550-141-825/1201
As an EVERGY STAR Partner, Weil-McLain
has determined that this product meets the
ENERGY STAR guidelines for energy efficiency

Hazard Definitions
The following terms are used to bring attention to the presence of hazards of various risk levels or to
important information concerning product life.
Indicates presence of hazards that will cause severe personal injury, death or substantial
property damage if ignored.
Indicates presence of hazards that can cause severe personal injury, death or substantial
property damage if ignored.
Indicates presence of hazards that will or can cause minor personal injury or property
damage if ignored.
Indicates special instructions on installation, operation or maintenance that are important
but not related to personal injury hazards.
Symbol Definitions
The following symbols are used to indicate sequence of installation for:
Factory-assembled packaged boiler – block, jacket and controls. Sizes 3
through 6 only.
Factory-assembled block, no burner. Sizes 3 through 6 with jacket installed; water trim controls
shipped separately. Sizes 7 through 9 with jacket and water trim controls shipped separately.
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 24 of this manual is space to list CP number(s).
2
Read This Page First

Read all instructions before installing. Failure to follow all instructions in proper order
can cause severe personal injury, death or substantial property damage.
Read This Page First . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Before Installing Boiler . . . . . . . . . . . . . . . . . . . . . . . . . . .4-5
Install Packaged Boiler . . . . . . . . . . . . . . . . . . . . . . . . . . .6-7
Install Non-Packaged Boiler . . . . . . . . . . . . . . . . . . . . . . .8-11
Connect Breeching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12-13
Connect Water Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . .14-18
Connect Tankless Heater Piping . . . . . . . . . . . . . . . . . . . .18-19
Connect Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20-21
Connect Oil Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Check-Out Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Installation and Service Certificate . . . . . . . . . . . . . . . . . .24
Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25-27
Parts List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Parts Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30-31
Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Back Cover
3
Table of Contents

Installations must comply with:
•U.S.
—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 pages 12-13. Boiler can be top
or back vented.
—Combustion and ventilation air supply. See
page 5.
—Oil supply. See page 22 for oil line routing.
—Electrical power.
•Check area around boiler. Remove any
combustible materials, gasoline and other
flammable liquids.
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.
Provide clearances around boiler
(see FIGURE 1):
Jacket cap must be in place on
boiler to avoid requiring an 18"
minimum clearance from back or top of boiler to
combustible material.
•Minimum clearances from vent pipe to
combustible material:
6 inches —Type “L” doublewall vent*
18 inches —Singlewall 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 ∆
•Special close clearances (alcove, closet, under
counters, etc.) — see Appendix, pages 26-27.
Top View
Walls
6"
6" (15")**
24"
6" (12") ∆
Before Installing Boiler
Recommended Service Clearances
FIGURE 1
Left Side
Floor
Wall
*
6"
(18")
*
6"
(18")
*
6"
(18")
Ceiling
24"
4

Provide air for combustion and ventilation:
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.
Do not install exhaust fan in boiler room.
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.
Go to page 6
to install boiler
BOILER FOUNDATION SIZE TABLE
MIN.
BOILER LENGTH WIDTH HEIGHT
MODEL INCHES INCHES INCHES
WTGO-3 17 22 2
WTGO-4 17 22 2
WTGO-5 20 22 2
WTGO-6 231/822 2
WTGO-7 261/422 2
WTGO-8 293/822 2
WTGO-9 321/222 2
5
Before Installing Boiler
Go to page 8
to install boiler
CONTINUED

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 2):
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 below).
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 requiring
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 working pressure.
Do not leave boiler unattended.
Cold water fill can expand and
damage cast iron, resulting in severe personal
injury, death or substantial property damage.
6. Check for maintained gauge pressure for more
than 10 minutes. 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.
6
Install Packaged Boiler
Go to page 12 to connect
breeching and venting

7
Install Packaged Boiler
Change From Back Flue Outlet to Top Flue Outlet (Optional)
FIGURE 2
CONTINUED

Fiberglass wool and ceramic fiber materials:
•POSSIBLE CANCER HAZARD
BY INHALATION
•CAN CAUSE RESPIRATORY,
SKIN AND EYE IRRITATION
This product contains fiberglass wool and ceramic
fiber materials. Airborne fibers from these materials
have been listed by the State of California as a
possible cause of cancer through inhalation. Apply
special care when handling ceramic fiber (chamber
lining and base insulation) materials. Ceramic fibers
can be converted to chrystobalites, a substance listed
as a probable cause of cancer.
Suppliers of fiberglass wool products recommend
the following precautions be taken when handling
these materials:
Precautionary measures:
•Avoid breathing fiberglass dust and contact
with skin and eyes.
•Use NIOSH approved dust/mist respirator.
•Wear long-sleeved, loose fitting clothing, gloves
and eye protection.
•Wash work clothes separately from other
clothing. Rinse washer thoroughly.
•Operations such as sawing, blowing, tearout
and spraying may generate airborne fiber
concentration requiring additional protection.
First aid measures:
•Eye contact — Flush eyes with water to remove
dust. If symptoms persist, seek medical attention.
•Skin contact — Wash affected areas gently
with soap and warm water after handling.
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 3):
1) Loosen two screws holding flue cap
strap to collector hood. Remove strap
and flue cap from opening.
Re-tighten screws.
2) Check rope placement inside flue cap.
(Read under Step #3 on page 9.)
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 3):
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.
8
Install Non-Packaged Boiler

3. Non-Packaged WTGO-7, 8 & 9 — install flue
collector hood (see FIGURE 3):
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 sections. 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 3.
d. Install washers and nuts. Tighten nuts
until collector 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.
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. lb.).
Install Non-Packaged Boiler
Change From Back Flue Outlet to Top Flue Outlet (Optional)
FIGURE 3
Sealing Rope in
Groove Inside Cap
Flue
Cap
Flue Cap
Strap
Flue Collector
Hood
Sealing Rope
with Adhesive
Tape
CONTINUED
9
Nut
Washer
Tinnerman
Clip
Screw
Hold-down
Lug

Perform hydrostatic pressure test:
1. Refer to FIGURE 4 and Control Tapping Table
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 working 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 property damage.
3. Check for maintained gauge pressure for more
than 10 minutes. 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 (sizes 7 through 9 only):
Before installing jacket, remove burner mounting
door. See jacket instructions for details.
Install boiler controls:
See Control Tapping Table and FIGURES 4 and 5
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.
CONTROL TAPPING TABLE
LOCATION SIZE FUNCTION
B1 1½" Return Piping
B2 1½" Alternate Return Piping
for “A” WTGO
C1½" Supply Piping
E3 ¾" Pressure-Temperature Gauge
H¾" Drain Valve
L¾" High Limit Control
(in Tankless Heater Cover Plate)
N½" Air Vent or
Expansion Tank Piping
R1 ¾" Relief Valve
Install Non-Packaged Boiler
Back SectionFront Section
B2
R1
NC
B1 H
CONTINUED
L
E3
Control Tapping Location
FIGURE 4
10

Water Boiler Controls
FIGURE 5
Relief
Valve
Circulator
Limit Control
Drain Valve
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.
Install burner (also refer to instructions packed with burner):
Burners designed for use with Weil-McLain 68 boilers must not be used on GOLD Oil
boilers. Contact individual burner manufacturers for GOLD Oil applications.
11
Install Packaged and Non-Packaged Boiler
Water
Pressure-Temperature
Gauge

General chimney requirements:
•Designed for natural draft firing. Connect
boiler to vertical chimney.
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:
6 inches —Type “L” doublewall vent
18 inches —Singlewall vent
•Minimum chimney sizes should be used.
Oversized chimneys, outside
masonry chimneys and/or
derated inputs can result in condensation
in chimney.
*6¾" x 6¾" inside liner
** 6½" x 10½" inside liner
*** Flue collar on boiler is 7" diameter
Connect breeching:
Long horizontal breechings,
excessive number 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 Chimney Size Table.
—Back outlet —see FIGURE 6.
—Top outlet —see FIGURE 7.
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
necessary 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.
MINIMUM CHIMNEY SIZE TABLE
*** MINIMUM
BOILER MINIMUM I=B=R MINIMUM
MODEL BREECHING CHIMNEY SIZE CHIMNEY
NUMBER DIAMETER RECT. ROUND HEIGHT
WTGO-3 5"
WTGO-4 6" 8" x 8" 6" 15'
WTGO-5 6" *
WTGO-6 7" 8" x 8" 7" 15'
WTGO-7 *
WTGO-8 8" x 12" 7" 20'
WTGO-9 7" **
12
Connect Breeching

Typical Location for
Barometric Control
(Also see Control
Manufacturer’s
Instructions)
Top Outlet Breeching Connection
FIGURE 7
Back Outlet Breeching Connection
FIGURE 6
13
Connect Breeching CONTINUED
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)

General piping information:
•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 a low water cutoff device when:
—Boiler is installed above radiation level.
—Required by certain state or local codes or
insurance companies.
Use low water cutoff designed for water
installations. Probe-type is recommended.
Purchase and install in tee in supply line
above boiler.
•Use backflow check valve in cold water supply
as required by local codes.
Install piping:
•See FIGURE 8 or 9 on page 15 and Water
Piping Size Table at right for near-boiler piping
and single-zone piping. See page 16 to complete
multiple-zone piping or page 17 to complete
piping for systems operating 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 8 or 9 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 8):
•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 8.
CLOSED expansion tank (FIGURE 9):
•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 9 to expansion tank. Use ½" N.P.T.
piping. Pitch any horizontal piping up towards
tank 1 inch per 5 feet of piping.
14
Connect Water Piping
*All piping sizes based on 20°F
temperature rise through boiler.
WATER PIPING SIZE TABLE *
BOILER
MODEL TO FROM
NUMBER SYSTEM 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"

Piping with DIAPHRAGM Expansion Tank
FIGURE 8
Piping with CLOSED Expansion Tank
FIGURE 9
Circulator
Automatic
Air Vent
From
System
Isolation
Valve
Cold
Water Fill
To
System
Relief
Valve
To Diaphragm
Expansion Tank and
Fittings
15
Connect Water Piping CONTINUED
Isolation
Valve
“N” Tapping
*Alternate Pump Location
“C” Tapping
*Circulator
Circulator
From
System
Isolation
Valve
To
System
Relief
Valve
Closed Type
Expansion Tank
Cold Water Fill
Isolation Valve
“N” Tapping
“B1” Tapping
“C” Tapping
*Circulator
*Alternate Pump Location
“B1” Tapping

Piping MULTIPLE ZONES:
1. Follow instructions on page 14 and 15 to install piping near boiler.
2. See FIGURE 10 or 11 to complete installation.
3. Zoning with circulators:
a. Size each circulator to individual circuit requirements.
b. Remove circulator (when furnished as standard equipment).
c. Install balancing valves to adjust flow to distribute heat to all zones.
d. Separate relay is required for each circulator.
4. Zoning with zone valves:
a. Install balancing valves to adjust flow to distribute heat to all zones.
b. Separate transformer is required to power zone valves. Refer to “Weil-McLain Zone Valve Wiring
Guide” for details.
Multiple Zoning With CIRCULATORS
FIGURE 10
Multiple Zoning With ZONE VALVES
FIGURE 11
Legend:
1Isolation valve
2Flow control valve
3Circulator
4Zone valve
5Drain valve
16
Connect Water Piping CONTINUED
ZONE 2
ZONE 1
ZONE 2
ZONE 1
11
2
5 5
1
2
3
1
1
4
55
1
1
1

Piping for systems requiring temperatures below 140°F:
In most systems, this type of piping is not required. If system water temperature requirements are less
than 140°F, such as radiant panels or converted gravity systems, use piping as shown in FIGURE 12 or
13. If system piping is plastic without an oxygen barrier, a heat exchanger must be used.
Piping with CIRCULATORS
FIGURE 12
Piping with ZONE VALVES
FIGURE 13
Legend:
1Isolation valve
2Flow control valve
3Circulator
4System temperature gauge
5Zone valve
6Drain valve
7System temperature valves
Adjust valves so that:
– the temperature at gauge 8 is at least 140°F
– the temperature at gauge 9 is at least 160°F
8Blend temperature gauge
9Boiler temperature gauge
17
Connect Water Piping CONTINUED

Use with refrigeration systems:
•Install boiler so that chilled medium 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 automatic means to prevent gravity
circulation during cooling cycle.
Hot Water Can Scald!
•Consumer Product Safety Commission and
some states recommend domestic hot water
temperature of 130°F or less.
•When installing an automatic mixing valve,
selection and installation must comply with valve
manufacturer’s recommendations and instructions.
•Water heated to a temperature suitable for
clothes washing, dish washing and other
sanitizing needs will scald and cause injury.
•Children, elderly, infirm or physically
handicapped persons are more likely to be
injured by hot water. Never leave them
unattended in or near a bathtub, shower or
sink. Never allow small children to use a hot
water faucet or draw their own bath. If anyone
using hot water in the building fits this
description, or if state laws or local codes
require certain water temperatures at hot
water faucets, take special precautions:
—Install automatic mixing valve set
according to those standards.
—Use lowest practical temperature setting.
—Check water temperature immediately after
first heating cycle and after any adjustment.
18
Connect Water Piping CONTINUED
Connect Tankless Heater Piping
Use with Refrigeration System
FIGURE 14
Supply
Circ. Circ.
Chiller
Strainer
Exp. Tank
Exp. Tank
1
1
1
1
2
1Isolation valve
2Balancing valve

Studies have indicated that
dangerous bacteria can form in
potable water distribution systems if certain
minimum water temperatures are not maintained.
Contact local health department for more information.
To pipe tankless heater:
1. Size piping no smaller than tankless heater
inlet and outlet.
2. Following controls (furnished by others) must
be installed:
a. Automatic mixing valve. See FIGURE 15.
(Read at bottom of page 18.)
b. Flow regulating valve. Size according to
intermittent draw of tankless heater. See
Table at right. Follow valve manufacturer’s
instructions to install.
3. Additional anti-scald devices may be installed at
each hot water faucet, bath and shower outlet.
4. In hard water areas, soften cold domestic supply
water to heaters to prevent lime build-up.
TANKLESS HEATER RATINGS TABLE
BOILER INTERMITTENT INLET
MODEL HEATER DRAW RATINGS AND OUTLET
NUMBER NUMBER (GPM)* TAPPING SIZES
WTGO-3 WT-14 3.25 ½"
WTGO-4 WT-14 3.75 ½"
WTGO-5 WT-14 4.00 ½"
WTGO-6 WT-14 4.25 ½"
WTGO-7 WT-20 5.50 ½"
WTGO-8 WT-20 5.75 ½"
WTGO-9 WT-20 6.00 ½"
*Gallons of water per minute heated from 40°F to 140°F with 200°F
boiler water temperature. Tested in accordance with I=W=H Testing and
Rating Standard for Indirect Tankless Water Heaters Tested with Boilers.
These single wall heat exchangers comply
with National Standard Plumbing Code
provided that:
•Boiler water (including additives) is
practically non-toxic, having a toxicity
rating or class of 1, as listed in Clinical
Toxicology of Commercial Products.
•Boiler water pressure is limited to max.
30 psig by approved water relief valve.
19
Connect Tankless Heater Piping CONTINUED
Tankless Heater Piping
FIGURE 15
Limit Control with
Tankless Control
Automatic Mixing
Valve
Flow Regulating
Valve Cold Water
Supply
12" min.
Cold
Hot
Mixed

General wiring requirements:
Electric shock hazard. Can cause
severe personal injury or death if
power source, including service switch on boiler,
is not disconnected before installing or servicing.
•Installations must follow these codes:
—National Electrical Code, ANSI/NFPA 70,
latest edition and any additional national,
state or local codes.
—In Canada, CSA C22.1 Canadian Electrical
Code Part 1 and any local codes.
•Wiring must be N.E.C. Class 1. If original wire
as supplied with boiler must be replaced, type
105°C wire or equivalent must be used. Supply
wiring to boiler and additional control wiring
must be 14 gauge or heavier.
•Provide electrical ground at boiler as required
by codes.
Thermostat wiring:
•Install thermostat on inside wall away from
influences of drafts, hot or cold water pipes,
lighting fixtures, television, sun rays or fireplaces.
•Follow instructions with thermostat. If it has a
heat anticipator, set heat anticipator in
thermostat to match power requirements of
equipment connected to it. Boiler wiring
diagrams give setting for standard equipment.
Junction box (furnished):
•Junction box houses electrical connections for
all boiler components.
•“P” boilers have harnesses furnished.
•“A” boilers are furnished with burner and limit
harnesses.
•All field-provided high voltage wiring must be
sheathed in flexible metal conduit.
•Connect incoming line voltage “HOT” wire to
service switch, and neutral wire to white wire.
Field-install equipment ground wire to green
wire with wire nut.
•Service switch (15 amp) is provided with boiler.
“A” boilers — install switch as shown.
•Some local codes may require an emergency
shut-off switch installed at a location away
from boiler. Follow local codes.
Burner wiring:
•Burner harness incorporates a disconnect
plug, providing a convenient way to disconnect
wiring when burner mounting door is opened.
•All “P” boilers have a power disconnect plug
installed on burner.
•On “A” boilers, mount the plug (provided in
water trim carton) on the burner housing as
shown in FIGURE 16. For Carlin burners, screw
burner plug into threaded conduit coupling,
then mount this assembly to the burner housing
using the chase nipple. Route wires through
housing and make connections in burner
junction box as shown in boiler wiring diagram.
Boiler Wiring for Forced Hot Water
FIGURE 16
Limit Control
Wiring Harness
Service Switch
on Boiler
Burner
Wiring
Harness
Burner
Disconnect
Plug
Circulator Wiring Harness
(Not Furnished on “A” Boilers)
20
Connect Wiring