550-110-132/1298
M
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D
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G
i
•
Installation
•
Start-Up
•
Service
•
Troubleshooting •
Repair Parts
CGiCGi
CGiCGi
CGi
Gas-fired boiler
Induced draft
Read all instructions before installing
InstallerInstaller
InstallerInstaller
Installer Leave this manual in the envelope and affix near the boiler.
Consider venting and piping locations when determining boiler location.
Any claims for damage or shortage in shipment must be filed immediately against
the transportation company by the consignee.
UserUser
UserUser
User Boiler Manual is only to be used and boiler installed by a qualified
installer/service technician.
User’s Information Manual is for your reference.
Regular service by your qualified service technician is recommended.
2 550-110-132/1298
CGi
When Calling or Writing About the Boiler
Please have boiler model number from boiler rating label and CP number from boiler jacket.
You may list the CP number in the space provided on page 33.
Read all instructions before installing boiler. Failure to follow instructions in proper
order can cause severe personal injury, death or substantial property damage.
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.
Read This Page First
3550-110-132/1298
CGi
Table of Contents
Read This Page First ................................................................................2
Table of Contents .................................................................................... 3
Before Installing Boiler.............................................................................4
Boiler Preparation....................................................................................7
Water Piping ............................................................................................8
Venting and Combustion Air ...............................................................18
Chimney Draft Venting..........................................................................19
Direct Exhaust Vent Location................................................................20
Direct Exhaust with AL29-4C ................................................................21
Gas Piping .............................................................................................29
Wiring .....................................................................................................30
Start-Up ..................................................................................................30
Check-Out Procedure ..........................................................................33
Installation and Service Certificate.....................................................33
Suggested Minimum Service ...............................................................34
Control System.......................................................................................36
Wiring Diagram .....................................................................................37
Sequence of Operation ........................................................................38
Operating Instructions ..........................................................................39
Troubleshooting ....................................................................................42
Parts List ..................................................................................................48
Ratings ...................................................................................................54
Dimensions ............................................................................................55
4 550-110-132/1298
CGi
Installations must comply with latest editions:
U.S.
— National, state and local codes, laws,
regulations and ordinances.
— National Fuel Gas Code, ANSI Z223.1.
— Standard for Controls and Safety
Devices for Automatically Fired
Boilers, ANSI/ASME CSD-1, when
required.
— National Electrical Code.
Canada
— National, provincial and local codes, laws,
regulations and ordinances.
— CAN/CGA B149.1 or B149.2 Installation
Code.
— C.S.A. C22.1 Canadian Electrical Code
Part 1.
Gas manifold and controls met safe lighting and
other performance criteria when boiler underwent
tests specified in ANSI Z21.13 - latest edition.
Before locating boiler:
Check for nearby connections to:
— System water piping.
— Venting connections.
— Gas supply piping.
— 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.
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.
●
●
●
●
●
All boilers experience some condensation in
section assembly during start-up. Flue gas con-
densate is slightly acidic. In most cases pH level is
not harmful to vents or drains. When combustion
air is contaminated by vapors from products or
areas listed below, condensate acidic levels in-
crease. Higher acidic levels attack many materi-
als, including stainless steels.
You may need to isolate the boiler if installation is
in an area containing contaminants listed below,
which will induce acidic contamination.
Products causing contaminated air:
1. spray cans containing chloro/fluorocarbons
2. permanent wave solutions
3. chlorinated waxes/cleaners
4. chlorine-based swimming pool chemicals
5. calcium chloride used for thawing
6. sodium chloride used for water softening
7. refrigerant leaks
8. paint or varnish removers
9. hydrochloric acid/muriatic acid
10. cements and glues
11. antistatic fabric softeners used in clothes
dryers
12. chloride-type bleaches, detergents, and
cleaning solvents found in household
laundry rooms
13. adhesives used to fasten building products
14. . . . and other similar products
Areas causing contaminated combustion air:
1. dry cleaning/laundry areas and shops
2. metal fabrication plants
3. beauty shops
4. refrigeration repair shops
5. photo processing plants
6. auto body shops
7. plastic manufacturing plants
8. furniture refinishing areas and shops
9. new building construction
10. remodeling areas
11. . . . and other similar areas
To prevent potential of severe
personal injury or death, check for
products or areas listed above before installing
boiler. If found:
● remove products permanently.
OR
● isolate boiler and provide outside combustion
air. See national, provincial or local codes for
further information.
Special note on combustion air supply:
Before Installing Boiler
●
5550-110-132/1298
CGi
Before Installing Boiler
●
●
●
Recommended service clearances
FIGURE 1
Minimum clearances for tight spaces
FIGURE 2
Hot water pipes - at least 1/2 inch from
combustible materials.
Recommended service clearances - Figure 1.
Minimum clearances for tight spaces - Figure 2.
Provide clearances:
7"
7"
24"
18"
35"
6"
2"
10"
3"
1"
15"
Fresh air openings
6" from bottom
and 6" from top
CONT’D
6 550-110-132/1298
CGi
When removing existing boiler from
common venting system:
Failure to follow all instructions
listed below can result in flue gas
spillage and carbon monoxide emissions, causing
severe personal injury or death.
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 operation, while the other appliances
remaining connected to the common venting system
are not in operation.
1. Seal any unused openings in the common
venting system.
2. Visually inspect the venting system for proper
size and horizontal pitch and determine there is
no blockage or restriction, leakage, corrosion
and other deficiencies which could cause an
unsafe condition.
3. Insofar as is practical, close all building doors
and windows and all doors between the space in
which the appliances remaining connected to
the common venting system are located and any
other spaces of the building. Turn on clothes
dryers and any appliance not connected to the
common 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 summer exhaust fan.
Close fireplace dampers.
4. Place in operation the appliance being inspected.
Follow the operating instructions. Adjust ther-
mostat so appliance will operate continuously.
5. Test for spillage at draft hood relief opening
after 5 minutes of main burner operation. Use
the flame of a match or candle, or smoke from a
cigarette, cigar or pipe.
6. 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 previous conditions of use.
Any improper operation of the 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 CAN/CGA B149.1 or
B149.2 Installation Code.
Before Installing Boiler
CONT’D
Lay a foundation, if needed:
CGi boiler is approved for use on combustible
flooring; however, boiler must not be installed
on carpeting.
Do not install boiler on carpeting even
if a foundation is used. Fire can result,
causing severe personal injury, death or substan-
tial property damage.
1. For residential garage installation, install
boiler so burners are at least 18 inches above
floor to avoid contact with gasoline fumes.
2. A level concrete or masonry foundation is
required when:
Water could flood area.
Non-level conditions exist.
●
●
TABLE 1 - Boiler foundation size
Boiler
Model
CGi - 25
CGi - 3
CGi - 4
CGi - 5
CGi - 6
CGi - 7
Length
Inches
25
25
25
25
25
25
Width
Inches
12
12
15
18
21
24
Min.
Height
Inches
2
2
2
2
2
2
7550-110-132/1298
CGi
Boiler Preparation
Place the boiler:
1. Leave boiler in crate and on pallet until
installation site is ready.
2. Move entire crate and pallet next to
selected location.
3. Remove crate.
4. Remove boiler from pallet:
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 backward off pallet and
into position.
Do not drop boiler or bump jacket
on floor or pallet. Damage to boiler
can result.
5. Check level. Shim legs, if needed. Do not
alter legs.
6. Remove front jacket door. Remove base
access panel.
7. Check for correctly-sized manifold orifices
from Table 2. The orifice size is stamped on the
orifice spud barrel.
Correctly-sized manifold orifices
must be used. Failure to do so will
result in severe personal injury, death or
substantial property damage.
8. Level and straighten burners.
Burners must be properly seated
in burner rest slots with their
openings face up. Main burner orifices must
inject down center of burner. Failure to prop-
erly seat burners will result in severe personal
injury, death or substantial property damage.
9. Reinstall burner access panel.
Burner access panel must be in
position during boiler operation to
prevent momentary flame rollout on main
flame ignition. Failure to do so will result in
severe personal injury, death or substantial
property damage.
Perform hydrostatic pressure test:
1. Pressure test boiler before attaching piping or
electrical supply.
2. Remove shipping nipple from supply outlet.
Remove relief valve.
3. Install air vent in tapping on top of boiler.
4. Plug remaining tappings, including relief valve
opening.
5. Connect water supply. Fill boiler and purge all
air. Test at 1-1/2 times working pressure.
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.
6. Check for maintained gauge pressure for more
than 10 minutes. Visually check for leaks if
gauge pressure drops.
7. Drain boiler and repair leaks if found.
Do not use petroleum-based
compounds to repair leaks.
Severe damage to boiler will occur, resulting in
severe personal injury, death or substantial
property damage.
8. Retest boiler after repairing leaks.
9. Remove testing plugs and air vent.
TABLE 2 - Manifold orifice size
Natural Gas Propane
U.S.
2.0 MM *
1.3 MM *
Canada
0 TO
2000 FT.
2000-
4500 FT.
2.0 MM
#49
1.3 MM #56
0 TO
2000 FT.
2000-
4500 FT.
* For elevations above 2000 feet, contact your local Weil-
McLain sales office for details.
8 550-110-132/1298
CGi
Water Piping
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 second control to minimum 20°F
above set point of first control. Maximum
allowable set point is 240°F. See page 37
for wiring.
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 boiler so that chilled medium is piped
in parallel with heating boiler. Use appropriate
valves to prevent chilled medium from enter-
ing 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.
●
●
●
Install piping:
1. See Figure 3A or 3B and Table 3 for near-boiler
piping and single-zone piping. See page 10 for
boilers used with refrigeration systems. See
page 11 to complete multiple-zone piping or
pages 12 – 17 to complete piping for radiant
panel systems or converted gravity systems.
2. Install relief valve vertically in tapping on side
of boiler. See Figure 3A or 3B and the tag
attached to the 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 dis-
charge line.
DIAPHRAGM expansion tank (Figure 3A):
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 instruc-
tions for details.
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.
2. Install automatic air vent as shown.
CLOSED expansion tank (Figure 3B):
1. Ensure expansion tank size will handle boiler
and system water volume and temperature.
See tank manufacturer’s instructions for
details.
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.
2. Connect tank to 1/2” N.P.T. tapping located
behind supply outlet, using 1/2” N.P.T. piping.
Pitch any horizontal piping up towards tank
1 inch per 5 feet of piping.
●
●
TO
SYSTEM
¾"
1"
1"
1"
1¼"
1¼"
TABLE 3 - WATER PIPING SIZE*
BOILER
MODEL
CGi - 25
CGi - 3
CGi - 4
CGi - 5
CGi - 6
CGi - 7
FROM
SYSTEM
¾"
1"
1"
1"
1¼"
1¼"
* All piping sizes based on 20
0
F temperature rise through
boiler.
9550-110-132/1298
CGi
Water Piping
For systems with low return water
temperature possible (such as con-
verted gravity systems and radiant heating sys-
tems), refer to the special piping suggestions of
pages 12 – 17. 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.
Piping with DIAPHRAGM expansion tank Piping with CLOSED expansion tank
Near boiler piping
For low return temperature systems, see additional requirements shown on pages 10 through 17
From
system
Cold
water
fill
To DIAPHRAGM
expansion tank
and fittings
Isolation
valve
Isolation
valve
To system
Circulator*
Circulator
Drain
valve
Relief
valve
Automatic
air vent
*
Alternate
location
To system
From
system
Isolation
valve
Drain
valve
Relief
valve
Circulator*
Isolation
valve
Circulator
Cold water fill
CLOSED type
expansion tank
*
Alternate
location
CONT’D
FIGURE 3A FIGURE 3B
10 550-110-132/1298
CGi
Water Piping
Piping MULTIPLE ZONES:
Piping for use with REFRIGERATION SYSTEMS:
Water
chiller
Expansion tank
Circulator
Check
valve
Strainer
Boiler
Shut-off
valve
System
supply
System
return
Balancing
valve
301-067b
CONT’D
FIGURE 4
Installing boiler on
REFRIGERATION SYSTEM
The boiler must be installed so the chilled medium
is piped in parallel with the heating boiler, using
appropriate valves to prevent the chilled medium
from entering boiler. Use piping as shown in
Figure 4.
If the boiler is connected to heating coils located in
air handling units where they can be exposed to
refrigerated air, gravity circulation during the
cooling cycle must be prevented with flow control
valves or other automatic means.
Piping for RADIANT HEATING SYSTEMS or CONVERTED GRAVITY SYSTEMS
c. Install balancing valves to adjust flow to dis-
tribute heat to all zones.
d. Separate relay is required for each circula-
tor.
4. Zoning with zone valves:
a. Install balancing valves to adjust flow to dis-
tribute heat to all zones.
b. Separate transformer is required to power
zone valves.
1. Follow instructions on pages 8 and 9 to install
near-boiler piping. (Also refer to Piping for radiant
heating systems or converted gravity systems if
applicable.)
2. See Figure 5A or 5B to complete installation.
3. Zoning with circulators:
a. Size each circulator to individual circuit re-
quirements.
b. Remove circulator on boiler.
Converted gravity (or steam) systems
Whenever possible, use the primary/secondary
piping shown in Figure 6A or 6B. This piping
design allows changing boiler flow rate without
affecting primary circuit flow rate.
If Figure 6A or 6B cannot be used, use the boiler
by-pass piping shown in Figure 7A or 7B.
You can also use the piping shown in Figure 8
(system by-pass) if the reduced flow rate in the
heating system will not cause heat distribution
problems.
Radiant heating systems
Preferably, use primary/secondary piping, as
shown in either Figure 6A or 6B. Alternatively, use
the method of either Figure 7A or 7B. Do not use
the piping of Figure 8, because this method does
not control radiant system supply temperature.
Failure to prevent low return water
temperature to the boiler could cause
corrosion of the boiler sections or burners, result-
ing in severe personal injury, death or substantial
property damage.
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
damage.
11550-110-132/1298
CGi
10
Cold
water
fill
11
12
9
ZONE 2
ZONE 1
1
11
2
2
3
1
6
6
13
10
Cold
water
fill
11
12
9
ZONE 2
ZONE 1
1
6
11
6
1
5
13
Alternate
pump
location
Water Piping
Zoning with circulators Zoning with zone valves
Typical piping for MULTIPLE ZONE installations
FIGURE 5B
FIGURE 5A
Applicable for systems with boiler return water temperature at least 130 °F
(Refer to pages 12 through 17 for low temperature systems)
1 Isolation valve
2 Flow/check valve
3 Circulator
5 Zone valve
6 Drain valve
9 Relief valve
10 Automatic air vent
11 Fill valve
12 Diaphragm expansion tank
(see Figure 3B if using closed type expansion tank. DO NOT use
automatic air vent with closed type expansion tank.)
13 In-line 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.)
Legend (For Figures 5A and 5B) .......................................................................................................................................
CONT’D
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 12 – 17. 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.
12 550-110-132/1298
CGi
Temperature gauges
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 temperature 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 8 reads 130 °F
when gauge 4a reads 60 °F.
4. Note that valve 7a regulates the amount of hot
water from the boiler supply which mixes with
return water. Valve 7b regulates the amount of
system water flowing through the boiler sec-
ondary loop.
Water Piping - Low Temp Systems
Figures 6A and 6B show suggested piping
arrangements for low temperature systems using
primary/secondary piping. (For alternatives, see
pages 14 through 17.)
Primary/secondary piping is preferred because the
flow rate and temperature drop in the heating
circuit(s) is determined only by the heating circuit
pumps(s). So adjustment of the by-pass valves in
the boiler circuit will not cause a change in the
heating circuit flow rate and temperature
distribution.
The by-pass 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 in the following
section.
Piping for RADIANT HEATING SYSTEMS or CONVERTED GRAVITY SYSTEMS —
By-pass arrangements using PRIMARY/SECONDARY piping (preferred)
Failure to prevent low return water
temperature to the boiler could cause
corrosion of the boiler sections or burners, result-
ing 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 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 damage.
Adjust valves as follows (Fig. 6A & 6B only):
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 the water temperature being supplied to
the radiant tubing.
Gauge 8 is 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 pressure/temperature gauge reads at
least 150 °F when the system return water is cold
(approximately 60 °F water temperature).
13550-110-132/1298
CGi
Water Piping - Low Temp Systems
Zoning with circulators
Zoning with zone valves
By-pass arrangements using PRIMARY/SECONDARY piping (PREFERRED)
for RADIANT HEATING SYSTEMS or CONVERTED GRAVITY SYSTEMS
Legend (For Figures 6A and 6B) .....................................................................................................................................
(Do not apply to systems using outdoor reset controls)
CONT’D
10
ZONE 2
ZONE 1
1
1
1
13
1
2
2
4a 4b
3
66
7b
7a
8
12"
MAX.
Cold
water
fill
11
12
9
Alternate
pump
location
10
Cold
water
fill
11
12
9
ZONE 2
ZONE 1
12"
MAX.
1
1
1
1
5
4a 4b
3
66
8
7b
13
7a
Alternate
pump
location
FIGURE 6B
FIGURE 6A
11 Fill valve
12 Diaphragm expansion tank
(see Figure 3B if using closed type expansion
tank. DO NOT use automatic air vent with
closed type expansion tank.)
13 In-line 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.)
1 Isolation valve
2 Flow/check valve
3 Circulator
4 System temperature gauges
5 Zone valve
6 Drain valve
7 System temperature valves
(see instructions at left for adjusting
valves)
8 Blend temperature gauge
9 Relief valve
10 Automatic air vent
14 550-110-132/1298
CGi
Adjust valves as follows (Fig. 7A & 7B only):
1. Start with valve 7a fully closed and 7b fully
open.
2. Gradually open valve 7a while closing valve 7b
until the temperature at gauge 8 reads 60 °F
higher than gauge 4a.
A minimum 60 °F temperature rise through the
boiler assures a low enough flow rate and high
enough average temperature to prevent
condensation even with low system return
water temperature.
3. Valve 7a regulates the system flow rate, while
valve 7b regulates the boiler flow rate.
4. The boiler-mounted temperature/pressure
gauge may be used in place of a separate
gauge 8.
Water Piping - Low Temp Systems
CONT’D
Piping for RADIANT HEATING SYSTEMS or CONVERTED GRAVITY SYSTEMS —
Alternate by-pass piping arrangements
Failure to prevent low return water
temperature to the boiler could cause
corrosion of the boiler sections or burners, result-
ing 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 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 damage.
Figures 7A and 7B are alternative piping sugges-
tions for large water content (converted gravity or
steam systems) or radiant heating sytems — for
use when primary/secondary piping can't be
applied. (Figure 8 is another alternative, using
system by-pass in place of boiler by-pass piping.
Figure 8, however, is not suitable for radiant
heating applications because it does not protect
the radiant system from possible high water
temperature.)
This piping method is called a "boiler by-pass"
because part of the pump flow is by-passed around
the boiler (through valve 7a). This method reduces
the flow rate through the boiler, in order to raise
the average water temperature in the boiler
enough to prevent flue gas condensation. Boiler
by-pass piping is effective for some boilers —
including the CGi — provided the flow rates are
adjusted according to the instructions following.
Boiler by-pass piping keeps system flow rate as
high as possible and temperature drop as low as
possible, helping to equalize the building heat
distribution.
Temperature gauges
Gauge 4a is optional if the by-pass valves will be
adjusted using cold (or room temperature) return
water to the boiler. (When setting the valves
without gauge 4a installed — using cold or room
temperature water — assume the return water
temperature to be 60 °F. Set the valves so gauge 8
reads at least 120 °F.)
Gauge 4b is optional on converted gravity systems,
but required on radiant heating systems — to
display the water temperature being supplied to
the radiant tubing.
Gauge 8 is required on all systems to assure
reliable adjustment of the by-pass valves. The
boiler-mounted pressure/temperature gauge can
be used if a separate temperature gauge is not
installed.
15550-110-132/1298
CGi
10
Cold
water
fill
11
12
9
ZONE 2
ZONE 1
1
11
1
2
2
4a 4b
3
66
7b
7a
8
13
10
Cold
water
fill
11
12
9
4a
8
4b
7a
7b
0302-067a
13
Alternate
pump
location
Water Piping - Low Temp Systems
CONT’D
Alternate by-pass piping arrangements
for RADIANT HEATING SYSTEMS or CONVERTED GRAVITY SYSTEMS
Boiler by-pass — Zoning with circulators
FIGURE 7B
FIGURE 7A
Boiler by-pass
— Zoning with zone valves
Alternatives to Figures 6A and 6B
(Do not apply to systems using outdoor reset controls)
Legend (For Figures 7A and 7B) .......................................................................................................................................
11 Fill valve
12 Diaphragm expansion tank
(see Figure 3B if using closed type expansion
tank. DO NOT use automatic air vent with
closed type expansion tank.)
13 In-line 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.)
1 Isolation valve
2 Flow/check valve
3 Circulator
4 System temperature gauges
5 Zone valve
6 Drain valve
7 System temperature valves
(see instructions at left for adjusting
valves)
8 Blend temperature gauge
9 Relief valve
10 Automatic air vent
16 550-110-132/1298
CGi
1. Start with valve 7a fully closed and 7b fully
open.
2. Gradually open valve 7a while closing valve 7b
until the temperature at gauge 8 reads
at least 130 °F at all times.
3. Valve 7a regulates the amount of boiler supply
water mixed with return water. Valve 7b
causes a pressure drop in the system needed
to balance flow through valve 7a and the
system.
4. The valve adjustment should be done with the
system at the coldest expected temperature
(60 °F for converted gravity systems or high
mass radiant systems).
Adjust valves as follows (Figure 8 only):
Water Piping - Low Temp Systems
CONT’D
Piping for CONVERTED GRAVITY SYSTEMS —
Alternate by-pass piping arrangement for large water content systems
Failure to prevent low return water
temperature to the boiler could cause
corrosion of the boiler sections or burners, result-
ing 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 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 damage.
Figure 8 is an alternate piping method that pro-
vides return water temperature control for boilers
installed on large water content systems (con-
verted gravity or steam systems).
Do not apply the piping of Figure 8 on radiant
heating systems. It provides no method of regulat-
ing the water temperature provided to the system,
and could result in excessive water temperature in
the radiant tubing.
This piping method is called a "system by-pass"
because part of the pump flow by-passes the
system (through valve 7a). This by-passed hot
water from the boiler outlet mixes with cooler
system return water temperature in order to
provide minimum 130 °F return water to the boiler.
Valve 7b will most often be full open, but may need
to be slightly closed on some low pressure drop
systems in order to cause enough flow through
valve 7a.
System by-pass piping as shown in Figure 8 can
be used with either zone-valve zoning or circulator
zoning. When used with circulator zoning, how-
ever, the boiler circulator, item 3, must be piped as
shown. It cannot be used as one of the zoning
circulators.
Do not apply system by-pass piping if the reduced
flow in the system could cause poor heat distribu-
tion. That is, system by-pass piping reduces the
flow in the system and increases the water tem-
perature supplied to the system. This can cause
increased heat from radiators at the beginning of
the system and reduced heat from radiators near
the end of the system.
17550-110-132/1298
CGi
Water Piping - Low Temp Systems
CONT’D
System by-pass —
Applies to
ANY
zoning method
Alternate by-pass piping arrangement
for CONVERTED GRAVITY (OR STEAM) SYSTEMS
Alternate to Figure 7A/7B — for converted gravity (or steam) systems only
(Do not apply to radiant heating systems)
Legend ...............................................................................................................................................
11 Fill valve
12 Diaphragm expansion tank
(see Figure 3B if using closed type expansion
tank. DO NOT use automatic air vent with
closed type expansion tank.)
13 In-line 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.)
1 Isolation valve
2 Flow/check valve
3 Circulator
4 System temperature gauges
5 Zone valve
6 Drain valve
7 System temperature valves
(see instructions at left for adjusting
valves)
8 Blend temperature gauge
9 Relief valve
10 Automatic air vent
10
Cold
water
fill
11
12
9
8
7a
7b
0302-067c
Alternate
pump
location
To systemFrom system
FIGURE 8
18 550-110-132/1298
CGi
Venting and Combustion Air
Venting method definitions:
1. Chimney draft venting - Category I appliance.
(non-positive vent static pressure and vent gas
temperature that avoids excessive condensate
production in vent). See page 19. Chimney
draft installation using:
a. Vent connector (single or doublewall) sized
to eliminate positive pressure in vent
system. Diameter increases immediately
at boiler.
b. Doublewall metal vent (B-vent) or chimney
with liner approved by National Fuel Gas
Code, ANSI Z223.1-latest edition, or in
Canada, CAN/CGA B149.1 or B149.2
Installation Code.
2. Direct exhaust - Category III appliance
(positive vent static pressure and vent gas
temperature that avoids excessive condensate
production in vent). See pages 20-28. Direct
exhaust installation using:
a. Vent pipe specified in these instructions.
b. Vent termination through outside wall,
roof or unused chimney. Tight chimney
areas will make vent joint construction
very difficult.
Combustion and ventilation air source:
Combustion and ventilation air openings must
comply with Section 5.3 of National Fuel Gas Code
ANSI Z223.1-latest edition, or applicable building
codes. Canadian installations must comply with
CAN/CGA B149.1 or B149.2 Installation Code.
Provide adequate combustion and
ventilation openings to assure
proper combustion, and prevent possibility of
flue gas spillage and carbon monoxide
emissions, which can result in severe personal
injury or death. Do not install exhaust fan in
boiler room.
For boilers located in confined rooms or in build-
ings of tight construction:
1. A confined room, as defined by National Fuel
Gas Code, is less than 50 cubic feet per 1000
Btuh input of all appliances in the room.
2. When air is taken from inside the building —
Provide 2 permanent openings, one within 12
inches of ceiling, one within 12 inches of floor.
Minimum dimension of each rectangular
opening should be at least 3 inches. Each
opening must be at least 1 square inch per
1000 Btuh input of all fuel burning appli-
ances (plus requirements for any equipment
that can pull air from room, including clothes
dryer and fireplace), but not less than 100
square inches. Openings must freely connect
with areas having adequate air flow from
outside.
3. When air is taken from outdoors — follow
either method described below:
a. Provide 2 permanent openings, one within
12 inches of ceiling, one within 12 inches
of floor. Minimum dimension of each
rectangular opening should be at least 3
inches. Openings must connect directly or
by ducts with outdoors or spaces (crawl or
attic) that freely connect to outside air. Size
as listed below:
1) Through outside wall or vertical duct -
at least 1 square inch per 4000 Btuh
input of all fuel burning appliances
(plus requirements for any equipment
that can pull air from room, including
clothes dryer and fireplace).
2) Through horizontal ducts - 1 square
inch per 2000 Btuh input of all fuel
burning appliances (plus requirements
for any equipment that can pull air
from room, including clothes dryer
and fireplace).
3) Other size ducts must comply with
local codes.
b. When boiler clearances from sides and
back are at least 1 inch and from the
front at least 6 inches, 1 permanent
opening may be provided within 12 inches
from ceiling. Opening must connect
directly or by ducts with outdoors or
spaces (crawl or attic) that freely connect
to outside air. Size as listed below:
1) 1 square inch per 3000 Btuh of total
input rating all fuel burning appli-
ances (plus requirements for any
equipment that can pull air from
room, including clothes dryer and
fireplace) . . . and . . .
2) Not less than the sum of all the areas
of all vent connectors in the room.
Boiler must be vented and
supplied with combustion and
ventilation air as described in these
instructions. Failure to do so will cause severe
personal injury or death.
19550-110-132/1298
CGi
Chimney Draft Venting
General venting information:
1. Use doublewall metal vent (B-vent) or chimney
with liner as required by National Fuel Gas
Code, ANSI Z223.1-latest edition, or in
Canada, CAN/CGA B149.1 or B149.2
Installation Code.
2. To prevent downdrafts, chimney should
extend at least 3 feet above highest point
where it passes through a roof and at least
2 feet higher than any portion of a building
within a horizontal distance of 10 feet.
3. To vent with another appliance, see National
Fuel Gas Code, ANSI Z223.1-latest edition, or
in Canada, CAN/CGA B149.1 or B149.2
Installation Code.
4. Inspect existing chimney before
installing boiler. Failure to clean
or replace perforated pipe or lining will cause
severe personal injury or death.
"D" Minimum
Vent connector diameter
4"
4"
5"
5"
5"
5"
TABLE 4 - Chimney draft venting
Boiler
Model
CGi - 25
CGi - 3
CGi - 4
CGi - 5
CGi - 6
CGi - 7
* See WARNING below regarding sizing and applicable
codes.
Chimney
Cleanout
Tight
seal
1/4" Rise/4 FT.
D
D
Increaser
Chimney draft venting
FIGURE 9
5. Do not connect breeching to any portion of a
mechanical draft system that can operate
under positive pressure.
6. Maintain minimum 2"clearance from combus-
tible materials to vent pipe.
7. Do not use chimney with an open fireplace.
8. Make horizontal runs as short as possible.
Long runs can cause condensation.
9. When longer runs are used, support pipe with
appropriate hangers.
10. To prevent blockage, do not vent into bottom
of chimney.
11. Vent pipe must not go beyond inside wall of
chimney.
12. Vent passing through floors or ceilings must
be firestopped.
13. See Figure 9 and Table 4 to connect boiler to
venting system.
Vent sizing given in Table 4 is only a
general guideline. The vent connector
and chimney must be designed, sized and con-
structed in compliance with all applicable codes,
including:
U. S. — National Fuel Gas Code, ANSI
Z223.1–latest edition.
Canada — CAN/CGA B149.1 or B149.2 Instal-
lation Code.
Failure to correctly size and install the vent sys-
tem could result in severe personal injury, death,
or substantial property damage.
20 550-110-132/1298
CGi
Direct Exhaust Vent Location
Follow instructions on this page when
determining vent location to avoid
possibility of severe personal injury, death or
substantial property damage.
1. Gases will form white plume in winter. Plume
could obstruct window view.
2. Prevailing winds could cause freezing of
condensate and water/ice buildup on
building, plants or roof.
3. Locate or guard vent to prevent accidental
contact by people or pets.
4. Do not terminate vent in window well, stair
well, alcove, courtyard, or other recessed
areas.
5. Vent termination must be located more than
4 feet below or 4 feet horizontally from any
door, window or gravity air inlet into any
building, and more than 1 foot above grade or
anticipated snowline. In addition, vent termi-
nation must be at least 7 feet above public
walkway and 3 feet above any forced air inlet
within 10 feet. Stay well away from trees,
shrubs, and decorative items. Site conditions
may dictate greater clearances. See Figure 10.
6. Vent must terminate at least 4 feet horizon-
tally, and in no case above or below, unless a
4 foot horizontal distance is maintained, from
electric meters, gas meters, regulators, relief
valves, and other equipment.
7. Locate or guard vent to prevent condensate
from damaging exterior finishes.
8. Do not extend exposed vent pipe outside of
building. Condensate could freeze and block
vent pipe.
9. Terminate vent at least 6 feet away from
adjacent walls.
10. Do not terminate vent closer than 5 feet below
roof overhang or parapet.
11. Do not terminate vent above any door,
window or gravity air inlet into any building.
Condensate can freeze, causing ice formations.
12. Do not connect:
• Any other appliance to vent pipe.
• Multiple boilers to a common vent pipe.
13. Do not wrap or insulate vent pipe and fittings.
14. Winds over 40 mph can cause nuisance boiler
shutdown if boiler is sidewall vented.
15. Canadian installations - Do not terminate vent
less than 6 feet from another combustion air
inlet or less than 3 feet from any other build-
ing opening or any gas service regulator.
16. For location of vertical termination, see vent
pipe manufacturer's instructions.
Vent termination locations
FIGURE 10
932EH
4 feet
4 feet
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