Crown Boiler AWI037 User manual

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Tel: [phone] • Fax: [phone] • www.crownboiler.com
Manufacturer of Hydronic Heatings Products
P.O. Box 14818 3633 I. Street
Philadelphia, PA 19134
AWI & TWI Series
Gas-Fired Natural Draft Hot Water Boilers
INSTALLATION INSTRUCTIONS
These instructions must be affixed on or adjacent to the boiler
WARNING: Improper installa-
tion, adjustment, alteration,
service or maintenance can
cause property damage, injury,
or loss of life. For assistance or
additionalinformation,consulta
qualified installer, service
agency or the gas supplier.
Read these instructions carefully
before installing.
Models:
• AWI037
• AWI061
• AWI095
• AWI128
• AWI162
• AWI195
• AWI229
• AWI262
• AWI295
• TWI061
• TWI095
• TWI128
• TWI162
CROWN
Boiler Co
CROWN
Boiler C
o

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INSIDE FRONT
COVER
(LEAVE BLANK)

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Table of Contents
I. Product Description .................................................. 1
II. Specifications ............................................................ 1
III. Before Installing ......................................................... 4
IV. LocatingtheBoiler...................................................... 4
V. Air for Combustion & Ventilation .............................. 5
VI. Venting ....................................................................... 8
VII. GasPiping ................................................................ 11
I Product Description
The AWI series boiler is a cast iron gas fired water boiler designed for use in closed forced circulation heating systems.
This boiler is a Category I draft diverter equipped appliance, which must be vented by natural draft using a lined masonry
or listed metal chimney system. An adequate supply of air for combustion, ventilation and dilution of flue gases must be
available in the boiler room.
The TWI series boiler is identical to corresponding sized AWI boiler except for the addition of baffles in the flue passages
to obtain higher AFUEs. The TWI is not available with a standing pilot or for use with propane gas.
VIII. System Piping ............................................. 12
IX. Wiring ......................................................... 16
X. Start-Up & Checkout .................................. 21
XI. Service & Maintenance............................... 27
XII. Troubleshooting ......................................... 29
XIII. Parts ............................................................ 34
II Specifications
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FIGURE1A: STANDARDCONFIGURATION(SEEPAGE3FORLETTERDIMENSIONS)

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FIGURE1B:“LEFTPIPED”CONFIGURATION
FIGURE1C:“TOPPIPED”(T-AWIORT-TWI) CONFIGURATION

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TABLE1:SPECIFICATIONS
Notes:
Suffix E = Intermittent Ignition, Suffix S = Standing Pilot
Add Suffix N for Natural Gas or Suffix L for Propane Gas to basic AWI Boiler Model shown (Example: AWI295EN, AWI229SL)
CISAB RELIOB LEDOM
*SESAGPLDNALARUTAN-SGNITAR )SEHCNI(SNOISNEMID
REBMUN FO SNOITCES
TUPNI EOD GNITAEH YTICAPAC
TENR=B=I ,GNITAR RETAW EUFA
"A""B""C""D""E""F"
HBMHBMHBM%
S730IWA E730IWA 27303620.08 3.28 2/1-01
8/7-72
4/1-748/5-38/7-3
S160IWA E160IWA 31605340.08 6.28 4/3-118/7-548/5-38/7-1
S590IWA E590IWA 45987861.08 3.28 512/1-758/1-48/7-1
S821IWA E821IWA 5821501192.08 0.28 4/1-818/1-968/5-48/7-1
S261IWA E261IWA 6261231511 3.08 7.18 2/1-124/3-0168/5-48/7-1
S591IWA E591IWA 7591951831 4.08 4.18 4/3-42
8/7-92
8/3-2178/1-58/7-1
S922IWA E922IWA 8922681261 4.08 2.18 82417 8/1-58/7-1
S262IWA E262IWA 9262212481 5.08 9.08 4/1-138/5-5188/5-58/7-1
S592IWA E592IWA 01592832702 7.08 6.08 2/1-434/1-7188/5-58/7-1
CISAB RELIOB LEDOM REBMUN FO SNOITCES
YLNOSAGLARUTAN-SGNITAR )SEHCNI(SNOISNEMID
TUPNI EOD GNITAEH YTICAPAC
TENR=B=I ,GNITAR RETAW EUFA
"A""B""C""D""E""F"
HBMHBMHBM%
E160IWT31615440.384/3-11
8/7-72
8/7-548/5-38/7-1
E590IWT45997960.38512/1-758/1-48/7-1
E821IWT5821601290.384/1-818/1-968/5-48/7-1
E261IWT62614317110.382/1-124/3-0168/5-48/7-1
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III Before Installing
1) Safe, reliable operation of this boiler depends upon installation by a professional heating contractor in strict accordance
with this manual and the requirements of the authority having jurisdiction.
•In the absence of an authority having jurisdiction, installation must be in accordance with this manual and the
National Fuel Gas Code, ANSI Z223.1-latest edition.
•Where required by the authority having jurisdiction, this installation must conform to the Standard for Controls
and Safety Devices for Automatically Fired Boilers (ANSI/ASME CSD-1)-latest edition.
2) Make sure that a properly sized chimney is available which is in good condition. Consult the authority having jurisdiction,
Part VI of this manual, and the National Fuel Gas Code for additional information on venting requirements.
3) Make sure that the boiler is correctly sized:
•For heating systems employing convection radiation (baseboard or radiators) use an industry accepted sizing
method such as the I=B=R Heat Loss Calculation Guide (Pub. #H21 or #H22) published by the Hydronics Institute
in Berkeley Heights NJ.
•For new radiant heating systems refer to the radiant tubing manufacturer’s boiler sizing guidelines.
•For systems including a Crown Mega-Stor indirect water heater, size the boiler to have either the DOE Heating
Capacity required for the Mega-Stor or the net rating required for the heating system, whichever results in the
larger boiler.
•For systems that incorporate other indirect water heaters, refer to the indirect water heater manufacturer’s instruc-
tions for boiler output requirements.
4) Make sure that the boiler received is configured for the correct gas (natural or LP).
5) Boilers built for installations at altitudes above 2000 ft. require different burners and main burner orifice. Make sure that
the boiler is configured for use at the correct altitude.
IV Locating the Boiler
1) Clearances:
•Observe the minimum clearances shown below. These clearances apply to all combustible construction, as well as
noncombustible walls, ceilings and doors. Also see Figure 2.
Front – 18”
Left Side – 6”
Right Side – 6”
Rear – 6”
Top – 18”
•A 24” service clearance from the jacket is recommended on the left, right, and front of the boiler. These clearances
may be reduced to those shown in Figure 2, however servicing the boiler will become increasingly difficult as these
service clearances are reduced.
•If the right side 24” service clearance is reduced, adequate clearance must be maintained to easily read both the
gauge and the limit control. Alternatively, access to the gauge and limit may be provided using a door
2) The boiler must be installed on a hard level surface. This surface may be combustible.
3) Do not install this boiler in a location where gasoline or other flammable vapors or liquids will be stored or used. Do not
install this boiler in an area where large amounts of airborne dust will be present, such as a workshop.
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4) The boiler should be located as close to the chimney as possible.
5) Do not install this boiler over carpeting.
6) Do not install this boiler directly on a surface that may get wet. Raise the boiler on a pad.
V Air for Combustion and Ventilation
Sufficient fresh air must be supplied for combustion, ventilation and flue gas dilution. Provisions for combustion, ventilation
and flue gas dilution air for gas utilization equipment vented by natural draft must be made in accordance with local building
codes or, in absence of such codes, in accordance with sections 5.3.3 and 5.3.4 (“Air for Combustion and Ventilation”) of the
National Fuel Gas Code, NFPA 54/ANSI Z 223.1.
To ensure an adequate supply of combustion, ventilation and flue gas dilution air supply, start by determining whether the boiler
is to be installed in a building of unusually tight construction. A building of unusually tight construction is defined by the
National Fuel Gas Code as having all of the following features:
•Walls and ceilings exposed to outside atmosphere have a continuous water vapor retarder with a rating of 1 perm
or less with openings gasketed and sealed
•Weather stripping has been added on openable windows and doors
•Caulking and sealants are applied to areas such as joints around window and door frames, between sole plates and
floors, between wall-ceiling joints, between wall panels, at penetrations for plumbing, electrical, and gas lines, and
at other openings.
For Buildings of Other than Unusually Tight Construction
1) Determine whether the boiler is to be installed in a confined space - A confined space is defined by the National Fuel Gas
Code as having a volume less than 50 cubic feet per 1000 BTU/hr input of all appliances installed in that space. To determine
whether the boiler room is a confined space:
a. Total the input of all appliances in the boiler room in thousands of BTU/hr. Round the result to the next highest
1000 BTU/hr.
FIGURE2:CLEARANCEFROMBOILERTOALLTYPESOFCOMBUSTIBLECONSTRUCTIONAND
NONCOMBUSTIBLE CEILINGS, WALLS AND DOORS
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b. Find the volume of the room in cubic feet. The volume of the room in cubic feet is:
Length(ft)xwidth(ft)xceilingheight(ft)
In calculating the volume of the boiler room, consider the volume of adjoining spaces only if no doors are installed
between them. If doors are installed between the boiler room and an adjoining space, do not consider the volume
of the adjoining space, even if the door is normally left open.
c. Divide the volume of the boiler room by the input in thousands of BTU/hr. If the result is less than 50, the boiler
room is a confined space.
Example:
An AWI162EN and a water heater are to be installed in a room measuring 6 ft - 3 in x 7 ft with an 8 ft ceiling.
The water heater has an input of 30000 BTU/hr:
Total input in thousands of BTU/hr = (162000 BTU/hr + 30000 BTU/hr)/1000 = 192
Volume of room = 6.25 ft x 7 ft x 8 ft = 350 ft3
350/192 = 1.82. Since 1.82 is less than 50, the boiler room is a confined space.
2) Unconfined Space - Natural infiltration into the boiler room will normally provide adequate air for combustion and
ventilation without additional louvers or openings into boiler room.
3) Confined Space - Provide two openings into the boiler room, one near the floor and one near the ceiling. The top edge of
the upper opening must be within 12” of the ceiling and the bottom edge of the lower opening must be within 12” of the floor
(Figure 3).
•Each opening must have a free area of 1 square inch per 1000 BTU/hr input of all gas burning appliances in the
boiler room. The minimum opening dimension is 3 inches. Minimum opening free area is 100 square inches per
opening.
•If the total volume of both the boiler room and the room to which the openings connect is less than 50 cubic feet
per 1000 BTU/hr of total appliance input, install a pair of identical openings into a third room. Connect additional
rooms with openings until the total volume of all rooms is at least 50 cubic feet per 1000 BTU/hr of input.
•The “free area” of an opening takes into account the blocking effect of mesh, grills, and louvers. Where screens
are used, they must be no finer than ¼” (4 x 4) mesh.
•If providing openings into adjacent rooms is undesirable, combustion and ventilation air can be brought into the
boiler room from outdoors. See the instructions under “For Buildings of Unusually Tight Construction”.
FIGURE3:BOILERINSTALLEDINCONFINEDSPACE,
ALL AIR FROM INSIDE
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ForBuildingsofUnusuallyTightConstruction
1) Openings must be installed between the boiler room and the outdoors or a ventilated space, such as an attic or crawl
space, which communicates directly with the outdoors.
2) Two openings are required. The top edge of the upper opening must be within 12 inches of the ceiling. The bottom
edge of the lower opening must be within 12 inches of the floor.
3) Size openings and ducts as follows:
•Vertical ducts or openings directly outdoors (Figure 4, Figure 5, and Figure 6) - Each opening must have a free
cross sectional area of 1 square inch per 4000 BTU/hr of the total input of all gas-fired appliances in the boiler
room but not less than 100 square inches. Minimum opening size is 3 inches.
•Openings to outdoors via horizontal ducts (Figure 7) - Each opening must have a free cross sectional area of 1
square inch per 2000 BTU/hr of the total input of all gas fired appliances in the boiler room but not less than 100
square inches. Minimum opening size is 3 inches.
•The “free area” of an opening takes into account the blocking effect of mesh, grills, and louvers. Where screens
are used, they must be no finer than ¼” (4 x 4) mesh.
FIGURE4: ALLAIRFROMOUTDOORS,
VENTILATED CRAWL SPACE AND ATTIC
FIGURE5: ALLAIRFROMOUTDOORS,
VIAVENTILATEDATTIC
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VI Venting
Vent installation must be in accordance with local building codes, or the local authority having jurisdiction, or Chapters 7 and
10 of the National Fuel Gas Code, NFPA 54/ANSI Z 223.1.
Typical vent installation is illustrated by Figure 8. The components of vent installation are boiler draft diverter, vent damper,
vent connector and chimney. The AWI and TWI series boilers are equipped with a draft diverter which is built into the boiler;
do not attempt to install an external draft hood.
1) Acceptable Chimneys - The following chimneys may be used to vent AWI or TWI series boilers:
•Listed Type B or L gas vent - Install in accordance with the manufacturer’s instructions, the terms of its listing,
and applicable codes.
•Masonry Chimney - The masonry chimney must be constructed in accordance with the Standard for Chimneys,
Fireplaces, Vents, and Solid Fuel Burning Appliances (NFPA 211) and lined with a clay liner or other listed lining
system. Do not vent an AWI or TWI series boiler into an unlined chimney.
FIGURE6:ALLAIRFROMOUTDOORS,USING
OPENINGSINTOBOILERROOM
FIGURE7:ALLAIRFROMOUTDOORS,USING
HORIZONTALDUCTS INTOBOILER ROOM
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2) Acceptable Vent Connectors - The following may be used for vent connectors:
•Listed type B or L Gas Vent
•SingleWall GalvanizedPipe -Use 0.018”(26gauge orheavier). Thesize andlocation ofthechimney maynot permit
the use of a single wall connector in some cases. See Chapter 10 of the National Fuel Gas Code. Do not use single
wall pipe for vent connectors in attics.
•Other Vent Connectors Permitted by the National Fuel Gas Code.
3) Chimney and Vent Connector Sizing - Size the chimney and vent connector in accordance with Chapter 10 of the National
Fuel Gas Code.
4) Exterior Chimneys - An exterior chimney has one or more sides exposed to the outdoors below the roof line. There are two
conditions under which an exterior chimney may be used:
•In some very restrictive cases, the AWI and TWI series boilers may be vented into an exterior ceramic lined masonry
chimney. See Chapter 10 of the National Fuel Gas Code for information on when exterior chimneys may be used.
•An exterior masonry chimney may be used if it is lined with B vent or a listed chimney lining system.
5) This boiler may vented using a listed power venter. The power venter must be in sized and installed in accordance with
the power venter manufacturer’s instructions, the terms of the power venter listing, and applicable codes. The boiler must
be electrically interlocked with the power venter to prevent boiler operation if the power venter fails to operate. Before
deciding to use a power venter, make certain that the flue gas exiting the power venter will not damage adjacent
construction or other structures. Also make certain that the power venter terminal will not be subjected to winds which
could effect power venter operation.
6) Do not connect the vent of this appliance into any portion of a mechanical vent system operating under positive
pressure.
FIGURE8: TYPICALVENTSYSTEM
INSTALLATION AND COMPONENTS
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7) Do not connect the boiler into a chimney flue serving an open fireplace or other solid fuel appliance.
8) Prior to boiler installation, inspect chimney for obstructions or other defects and correct as required. Clean chimney as
necessary.
9) Vent pipe should slope upward from draft diverter not less than one inch in four feet. No portion of vent pipe should
run downward or have sags. Vent pipe must be securely supported.
10) The vertical section of vent pipe coming off the boiler should be as tall as possible, while still maintaining the proper
clearance from the horizontal vent connector to combustibles and the proper pitch called for in (9) above.
11) Vent pipe should be installed above the bottom of the chimney to prevent blockage.
12) Vent pipe must be inserted flush with inside face of the chimney liner and the space between vent pipe and chimney
sealed tight.
13) Do not install the vent damper in any portion of the vent system which is used by appliances other the boiler being
installed.
14) Vent damper installation is mandatory on all AWI/TWI boiler models due to federally mandated efficiency regulations.
Install vent damper (see Figure 9) as follows:
a) Open vent damper carton and remove installation instructions. Read the instructions thoroughly before proceeding.
Verify that vent damper is same size as draft diverter outlet. See Figure 1. Unpack vent damper carefully. Do not
force closed damper blade. Forcing vent damper closed may result in damaged gear train and void warranty.
b) Vent damper is factory shipped having approximately ¾” diameter hole in the vent damper blade, which must be
left open for boilers equipped with standing pilot, and should be plugged on boilers with EI control system, using
the plug supplied with the damper.
Mount the vent damper on the flue collar without modification to either and secure with sheet metal screws. Make
sure screws do not interfere with damper blade operation. Vent damper blade position indicator must be visible to
users.
c) The damper wire harness is shipped wired into the boiler limit control. Plug the loose end of this harness into the
damper and secure the flexible conduit to the damper using a connector nut provided.
Provide adequate clearance to combustible construction and servicing.
d) Install vent connector pipe and vent fittings from vent damper outlet to chimney or gas vent. Secure with sheet
metal screws and support as required.
Removing an Existing Boiler from a Common Chimney
In some cases, when an existing boiler is removed from a common chimney, the common venting system may be too large
for the remaining appliances. 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
FIGURE9: VENTDAMPERINSTALLATIONDETAILS
RIGHTSIDEVIEW
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connected to the common venting system are not in operation.
a) Seal any unused opening in the common venting system.
b) Visually inspect the venting system for proper size and horizontal pitch and determine there is no blockage or
restriction, leakage, corrosion and other deficiencies which could cause an unsafe condition.
c) Insofar as practical, close all building doors and windows and all doors between the space in which all the appliances
remaining connected to the common venting system are located and 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
fireplacedampers.
d) Place in operation the appliance being inspected. Follow the lighting instructions. Adjust thermostat so the appliance
will operate continuously.
e) Test for spillage at the draft hood relief opening after five (5) minutes of main burner operation. Use the flame of a
match or candle, or smoke from a cigarette, cigar, or pipe.
f) After it has been determined that each appliance remaining connected to the common venting system properly vents
when tested as outlined above, return doors, windows, exhaust fans, fireplace dampers and any other gas-burning
appliances to their previous condition of use.
g) Any improper operation of the common venting system should be corrected so the installation conforms with the
National Fuel Gas Code, ANSI Z223.1. When resizing any portion of the common venting system, the common
venting system should be resized to approach the minimum size as determined using the appropriate tables in Part 10 of
theNationalFuelGasCode,ANSIZ223.1.
VII Gas Piping
Gas piping to the boiler must be sized to deliver adequate gas for the boiler to fire at the nameplate input at a line
pressure between the minimum and maximum values shown on the rating plate. For more information on gas line sizing,
consult the utility or Part 2 of the National Fuel Gas Code.
Figure 10 shows typical gas piping connection to the AWI/TWI boiler. A sediment trap must be installed upstream of all
gas controls. Install a manual shut-off valve outside the jacket and ground joint union as shown.
The boiler and its gas connection must be leak tested before placing the boiler in operation. When doing this, the boiler
and its individual shut-off must be disconnected from the rest of the system during any pressure testing of that system at
pressures in excess of 1/2 psi. When pressure testing the gas system at pressures of 1/2 psi or less, isolate the boiler from the
gas supply system by closing its individual manual shut-off valve.
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FIGURE10: GASCONNECTIONTOBOILER
*State of MassachusettsRequires Manual
Shut-offValve to be “T” Handle Type
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VIII System Piping
StandardPiping
Figure 11 shows typical boiler system connections on a single zone system. Additional information on hydronic system
design may be found in Installation of Residential Hydronic Systems (Pub. #200) published by the Hydronics Institute in
Berkeley Heights, NJ. The components in this system and their purposes are as follows:
1) Relief valve (Required) - Mount the relief valve on the right side of the boiler as shown in Figure 1 using the 3/4 nipples
and elbow provided. The relief valve shipped with the boiler is set to open at 30 psi. This valve may be replaced with
one having a pressure up to the “Maximum Allowable Working Pressure” shown on the rating plate If the valve is
replaced, the replacement must have a relief capacity in excess of the DOE heating capacity for the boiler.
Pipe the discharge of the relief valve to a location where water or steam will not create a hazard or cause property
damage if the valve opens. The end of the discharge pipe must terminate in an unthreaded pipe. If the relief valve
discharge is not piped to a drain it must terminate at least 6 inches above the floor. Do not run relief valve discharge
piping through an area that is prone to freezing. The termination of the relief valve discharge piping must be in an area
where it is not likely to become plugged by debris.
2) Circulator (Required) - Although the circulator is shipped on the boiler return, it can be installed on the boiler supply. If
the circulator is moved to the supply it should be positioned just downstream of the expansion tank as shown in Figure
11.
3) Expansion Tank (Required) - If this boiler is replacing an existing boiler with no other changes in the system, the old
expansion tank can generally be reused. If the expansion tank must be replaced, consult the expansion tank
manufacturer’s literature for proper sizing.
4) Fill Valve (Required) - Either a manual or automatic fill valve may be used. The ideal location for the fill is at the
expansion tank.
5) Automatic Air Vent (Required) - At least one automatic air vent is required. Manual vents will usually be required in
other parts of the system to remove air during initial fill.
CAUTION
• INSTALL BOILER SO THAT THE GAS IGNITION SYSTEM COMPONENTS ARE PROTECTED
FROM WATER (DRIPPING, SPRAYING, RAIN, ETC.) DURING APPLIANCE OPERATION AND
SERVICE (CIRCULATOR REPLACEMENT, ETC.).
• OPERATION OF THIS BOILER WITH CONTINUOUS RETURN TEMPERATURES BELOW 120°F
CAN CAUSE SEVERE HEAT EXCHANGER CORROSION DAMAGE.
• OPERATION OF THIS BOILER IN A SYSTEM HAVING SIGNIFICANT AMOUNTS OF
DISSOLVED OXYGEN CAN CAUSE SEVERE HEAT EXCHANGER CORROSION DAMAGE.
• DO NOT USE TOXIC ADDITIVES, SUCH AS AUTOMOTIVE ANTIFREEZE, IN A HYDRONIC
SYSTEM.
DANGER
• PIPE RELIEF VALVE DISCHARGE TO A SAFE LOCATION.
• DO NOT INSTALL A VALVE IN THE RELIEF VALVE DISCHARGE LINE.
• DO NOT MOVE RELIEF VALVE FROM FACTORY LOCATION.
• DO NOT PLUG RELIEF VALVE DISCHARGE.
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6) Low Water Cut-Off (Required in some situations) - A low water cutoff is required when the boiler is installed above
radiation. In addition, some codes such as ASME CSD-1 require low water cutoffs. Codes may also require that this
low water cutoff have a manual reset function. The low water cutoff may be a float type or probe type, but must be
designed for use in a hot-water system. The low water cutoff should be piped into the boiler supply just above the boiler
with no intervening valves between it and the boiler.
Use a low water cutoff that breaks the 120 VAC supply to the boiler. Do not attempt to wire a 24-volt low water cutoff
into the boiler factory wiring.
7) Manual Reset High Limit (Required by some codes) - This control is required by ASME CSD-1 and some other codes.
Install the high limit in the boiler supply piping just beyond the boiler with no intervening valves. Set the manual reset
high limit as far above the operating limit setting as possible, but not over 240°F. Wire the control to break the 120
VAC electrical supply to the boiler.
8) Flow Control Valve (Required under some conditions) - The flow control valve prevents flow through the system unless
the circulator is operating. A flow control valve may be necessary on converted gravity systems to prevent gravity
circulation. Flow control valves are also used to prevent “ghost flows” in circulator zone systems through zones that are
not calling for heat.
9) Isolation Valves (Optional) - Isolation valves are useful if the boiler must be drained, as they will eliminate having to
drain and refill the entire system.
10) Drain Valve - The drain valve is shipped in the boiler parts bag. Install it in the tee under the circulator as shown in
Figure 1. Piping for Special Situations
Certain types of heating systems have additional requirements. Some of the more common variations follow:
1) Indirect Water Heaters - Figure 12 shows typical indirect water heater piping. Boiler piping is the same as for any two-
zone system. Figure 12 shows circulator zoning, which is usually preferred for indirect water heaters. Size the
circulator and indirect water heater piping to obtain the boiler water flow through the indirect water heater called for by
the indirect water heater manufacturer.
FIGURE11: STANDARDBOILERPIPING
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2) LargeWater VolumeSystems -The pipingshown inFigure 13will minimizethe amountof timethat the boileroperates with
return temperatures below 120°F on these systems. A bypass is installed as shown to divert some supply water directly
into the return water. The bypass pipe should be the same size as the supply. The two throttling valves shown are
adjusted so that the return temperature rises above 120°F during the first few minutes of operation. A three-way valve can
be substituted for the two throttling valves shown. If the circulator is mounted on the supply, the bypass must be on the
discharge side of the circulator.
3) Low Temperature Systems - Some systems, such as radiant tubing systems, require the system water temperature to be
limited to a value below the temperature of the water leaving the AWI or TWI. These systems also typically have return
temperatures well below the 120°F minimum.
Figure 14 illustrates the use of a heat exchanger to connect the AWI or TWI boiler to this type of system. The heat
exchanger will permit the transfer of heat from the boiler water to the low temperature system while holding the system
supply and boiler return temperatures within their limits. For this system to work properly the heat exchanger must be
properly sized and the correct flow rates are required on either side of the heat exchanger. Consult the heat exchanger
manufacturer for sizing information. The water in the boiler is completely isolated from the water in the system. This
means that separate fill and expansion tanks are required for the heating system loop.
There are several other ways to connect low temperature systems to the non-condensing boilers like the AWI or TWI
such as four way mixing valve and variable speed injection pumping systems.
4) Systems containing oxygen - Many hydronic systems contain enough dissolved oxygen to cause severe corrosion damage
to a cast iron boiler such as the AWI or TWI. Some examples include:
• Radiant systems that employ tubing without an oxygen barrier.
• Systems with routine additions of fresh water.
• Systems which are open to the atmosphere.
If the boiler is to be used in such a system, it must be separated from the oxygenated water being heated with a heat
exchanger as shown in Figure 14.
Consult the heat exchanger manufacturer for proper heat exchanger sizing as well as flow and temperature
requirements. All components on the oxygenated side of the heat exchanger, such as the pump and expansion tank,
must be designed for use in oxygenated water.
FIGURE12: INDIRECTWATERHEATER
BOILER SIDE PIPING
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FIGURE 13: BOILER BYPASS PIPING
FIGURE14: ISOLATIONOFBOILERFROMSYSTEM
WITH A HEAT EXCHANGER
5) Piping with a Chiller - If the boiler is used in conjunction with a chiller, pipe the boiler and chiller in parallel as shown in
Figure 15. Use isolation valves to prevent chilled water from entering the boiler.
6) Air Handlers - Where the boiler is connected to air handlers through which refrigerated air passes, use flow control valves
in the boiler piping or other automatic means to prevent gravity circulation during the cooling cycle.
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IX Wiring
Single Zone Wiring
1) 120 Volt Wiring - The boiler should be provided with its own 15A branch circuit with fused disconnect. All 120 volt
connections are made inside the L8148E aquastat relay as follows (also see Fig. 16 or 17):
•Hot (“black”) - Terminal “L1”
•Neutral (“white”) - Terminal “L2”
•Ground (“green” or bare) - Ground screw on case of L8148E
2) Thermostat Wiring - Follow thermostat manufacturer instructions. To insure proper thermostat operation, avoid
installation in areas of poor air circulation, hot spots (near any heat source or in direct sunlight), cold spots (outside
walls, walls adjacent to unheated areas, locations subject to drafts). Provide Class II circuit between thermostat and
boiler. Connect thermostat wire leads to terminals T and TV inside L8148E aquastat relay.
FIGURE15: BOILERPIPINGWITHCHILLER
WARNING
All wiring and grounding must be done in accordance with the authority having jurisdiction or, in the absence of
such requirements, with the National Electrical Code (ANSI/NFPA 70)
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FIGURE16: WIRINGDIAGRAM,CONTINUOUSIGNITION
(STANDING PILOT) SYSTEM
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FIGURE17: WIRINGDIAGRAM,INTERMITTENTIGNITION
(EI) SYSTEM
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Wiring Variations
1) Multiple Circulator Zones – Figure 18 shows wiring for two or more circulator zones using Honeywell R845As. One
R845A is required for each circulator zone. Circulator terminals “C1” and “C2” on the L8148E are not used. A DPST
Honeywell RA832A may be substituted in place of the R845A using the “X” and “X” terminals in place of the “5” and “6”
terminals on a R845A.
A call for heat from any thermostat will energize the DPST relay in that zone’s R845A. When this relay is energized,
electrical continuity is created between terminals 3 and 4, energizing the circulator for that zone. At the same time, electri-
cal continuity is created between terminals 5 and 6 on the R845A, creating a current path from terminal “T” to “TV” on the
L8148E. Assuming that the supply water temperature is below the high limit setting, the normal ignition sequence will be
initiated.
2) Multiple Zones using Zone Valves – Figure 19 shows wiring for multiple zones using Honeywell V8043F zone valves. This
wiring diagram may be used for other 24-volt zone valves as long as they are equipped with end switches. Do not attempt to
use the transformer on the L8148E to power the zone valves; use a separate transformer. Up to five V8043Fs may be
powered by one 48VA transformer, such as the Honeywell AT87A.
A call for heat from a given thermostat will result in the application of 24 volts across the TH and TR terminals on the
corresponding zone valve, energizing the zone valve motor. The zone valve opens and the end switch contacts are then
made. The end switches are connected in parallel with each other and to the “T” and “TV” thermostat connections so that
any zone valve that opens will also start the circulator and fire the boiler (assuming the high limit is not open). Zone valve
terminal TH/TR has no internal connection on the zone valve; it is merely a “binding post” used to connect two or more
wires.
FIGURE18:CIRCULATORZONEWIRINGUSINGHONEYWELLR845As
(FACTORY BOILER WIRING NOT SHOWN - SEE FIGURE 16 OR 17)
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