Crown Boiler TWZ065 User manual

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TWZ Series
Oil-Fired Hot Water Boilers
INSTALLATION INSTRUCTIONS
These instructions must be afxed on or adjacent to the boiler
Models:
• TWZ065
• TWZ075
• TWZ100
• TWZ090
• TWZ125
• TWZ150
• TWZ120
• TWZ175
• TWZ200
WARNING: Improper instal-
lation, adjustment, alteration,
service or maintenance can
cause property damage, injury,
or loss of life. For assistance or
additional information, consult a
qualied installer, service agency
or the oil supplier. Read these
instructions carefully before
installing.
DESIGNED TO LEAD
Manufacturer of Hydronic Heating Products
P.O. Box 14818 3633 I. Street
Philadelphia, PA 19134
www.crownboiler.com

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FOLLOW ALL INSTRUCTIONS and warnings
printed in this manual and posted on the boiler.
INSPECT THE BOILER, BURNER AND
CONTROLS ANNUALLY. To keep your boiler safe
and efficient, have a service technician follow the
Service checklist near the end of this manual.
IF YOU ARE NOT QUALIFIED to install or service
boilers, do not install or service this one.
THE BOILER MAY LEAK WATER at the end of
its useful life. Be sure to protect walls, carpets,
and valuables from water that could leak from the
boiler.
PROTECT YOUR HOME IN FREEZING
WEATHER. A power outage, safety lockout, or
component failure will prevent your boiler from
lighting. In winter, your pipes may freeze and
cause extensive property damage. Do not leave
the heating system unattended during cold weather
unless alarms or other safeguards are in place to
prevent such damage
DO NOT BLOCK AIR FLOW into or around the
boiler. Insufficient air may cause the boiler to
produce carbon monoxide or start a fire.
KEEP FLAMMABLE LIQUIDS AWAY from the
boiler, including paint, solvents, and gasoline.
The boiler may ignite the vapors from the liquids
causing explosion or fire.
KEEP CHILDREN AND PETS away from hot
surfaces of the boiler, boiler piping, and vent pipe.
CARBON MONOXIDE (CO) is an odorless, deadly
gas that may be introduced into your home by
any malfunctioning fuel-burning product or vent
system failure. Consider installing CO alarms near
bedrooms in all levels of the building to warn you
and your family of potential CO exposure.
READ THIS ENTIRE MANUAL before attempting
installation, start-up, or service. Improper
installation, adjustment, alteration, service, or
maintenance may cause serious property damage,
personal injury, or death.
DO NOT DISCONNECT PIPE FITTINGS on the
boiler or in the heating system without first verifying
that the system is cool and free of pressure and
that your clothing will protect you from a release
of hot water or steam. Do not rely solely on the
boiler’s temperature and pressure gage when
making this judgment.
USE PROPER PERSONAL PROTECTION
EQUIPMENT when servicing or working near the
boiler. Materials of construction, flue products, and
fuel contain alumina, silica, heavy metals, carbon
monoxide, nitrogen oxides, and/or other toxic or
harmful substances that can are hazardous to
health and life and that are known to the State of
California to cause cancer, birth defects, and other
reproductive harm.
INSTALL ALL GUARDS, cover plates, and
enclosures before operating the boiler.
SIZE THE BOILER PROPERLY relative to the
design heat load or, if using domestic hot water
priority, the peak hot water load, whichever
is larger. A grossly oversized boiler will cycle
excessively and this will lead to premature failure
of the boiler and its components. Our warranty
does not apply to damage from excessive cycling.
ADHERE TO ALL LOCAL CODE
REQUIREMENTS. Contact your local code
inspector prior to installation. In the absence of
a local code, adhere to the latest editions of the
Installation of Oil Burning Equipment ANSI/NFPA
31 in the USA or CAN/CSA B139, Installation Code
for Oil Burning Equipment in Canada.
ALL WIRING must comply with the National
Electrical Code ANSI/NFPA 70 (in the USA) or the
Canadian Electrical Code CSA C22.1 (in Canada)
and any local regulations.
WARNINGS FOR THE HOMEOWNER
WARNINGS FOR THE INSTALLER

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Table of Contents
I. Product Description .............................................................. 2
II. Specications ........................................................................ 2
III. Before Installing.................................................................... 3
IV. Locating the Boiler ............................................................... 4
V. Air for Combustion & Ventilation......................................... 6
VI. Venting ................................................................................ 10
VII. System Piping Connections ................................................ 12
I Product Description
The TWZ series boiler is a cast iron oil-red water boiler designed for use in closed forced circulation heating systems.
This boiler must be vented by natural draft into a lined masonry or metal chimney, or Type L vent. An adequate supply of
air for combustion, ventilation and dilution of ue gases must be available in the boiler room. An optional tankless heater is
available to generate domestic hot water.
II Specications
VIII. Tankless Heater Piping...................................16
IX. Fuel Line Piping ........................................... 17
X. Wiring ........................................................... 20
XI. Start-up and Checkout .................................. 23
XII. Service & Maintenance ................................ 25
XIII. Parts .............................................................. 28
FIGURE 1: GENERAL CONFIGURATION *

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TABLE 1a: GENERAL SPECIFICATIONS
Notes:
1. Net Ratings are based on piping and pick-up allowances of 1.15.
2. Burner Capacity Rating, GPH is based on #2 oil with a Gross
Heating Value equal to 140000 BTU/Gal.
3. Maximum Working Pressure, Water - 50 PSI.
4. Tankless Heater Ratings based on I=W=H test standard.
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 latest
edition of Installation of Oil Burning Equipment (ANSI/NFPA31).
• Where required by the authority having jurisdiction, this installation must conform to the latest edition of Standard for
Controls and Safety Devices for Automatically Fired Boilers (ANSI/ASME CSD-1).
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 ANSI/NFPA31 for additional information on venting requirements.
TABLE 1b: OPTIONAL TANKLESS HEATER RATINGS
Power (“Side Wall”) Venting - Important Note
Two problems arise when any oil-red appliance is power vented:
1. There is sometimes an accelerated rate of soot buildup on the oil burner cad-cell, spinner etc.
2. There is a potential for severe damage to the side of the structure in the event that the boiler operates at a high smoke
level. This can happen for many reasons, some of which are out of the control of both the installer and appliance
manufacturer.
Crown Boiler Company recommends the use of a chimney to vent the TWZ series boilers. If a power venter must be used, it
is the responsibility of the installer and power vent manufacturer to “engineer” the power vent system. CROWN BOILER
COMPANY WILL ASSUME NO RESPONSIBILITY FOR DAMAGE TO SIDING, ETC. FROM A POWER
VENTED OIL-FIRED BOILER. THIS APPLIES REGARDLESS OF THE CAUSE OF THE SOOTING.
"A" "B" "C"
TWZ065 3 0.65 80000 70000 86.1 16.0 17-3/8 8 5/16 6
TWZ075 3 0.75 91000 79000 85.8 16.0 17-3/8 8 5/16 6
TWZ100 3 1.00 120000 104000 84.3 16.0 17-3/8 8 5/16 6
TWZ090 4 0.90 111000 97000 86.0 20.0 22-3/8 10 13/16 7
TWZ125 4 1.25 152000 132000 85.1 20.0 22-3/8 10 13/16 7
TWZ150 4 1.50 179000 156000 84.0 20.0 22-3/8 10 13/16 7
TWZ120 5 1.20 147000 128000 86.0 24.0 27-3/8 13 5/16 8
TWZ175 5 1.75 212000 184000 85.1 24.0 27-3/8 13 5/16 8
TWZ200 5 2.00 241000 210000 84.7 24.0 27-3/8 13 5/16 8
I=B=R Net
Rating (Btu/hr) AFUE (%)
Approx.
Water
Content (Gal)
Dimensions (inches)
Boiler Model
Number of
Sections
Burner
Input
(Gal/hr)
DOE Heating
Capacity
(Btu/hr)
TWZ065
TWZ075
TWZ100
TWZ090
TWZ125
TWZ150
TWZ120
TWZ175
TWZ200
Boiler Model
2.75
3.00
3.50
4.25
4.75
Tankless Heater Rating
(Gal/min)
3.25
3.25
3.75
4.00

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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 Guide RHH published by the Air-Conditioning, Heating and Refrigeration
Institute (AHRI).
• 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 Heating
Capacity required for the Mega-Stor or the I=B=R 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
instructions for boiler output requirements.
4) In some cases, boilers installed at altitudes above 2000ft may require a different burner conguration from that at sea
level. Consult the local Crown representative for more information.
IV Locating the Boiler
1) Clearances:
• Observe the minimum clearances shown below. Except as noted, these clearances apply to all combustible con-
struction, as well as noncombustible walls, ceilings and doors. Also see Figure 2.
Front – 24”
Left Side – 6”
Right Side – 6”
Rear – 6”
Top – 6”
Single Wall Chimney Connector (to combustible construction) - 18”
• A 24” service clearance from the jacket is recommended from the top of the boiler. This clearance may be
reduced to that shown above; however, servicing the boiler will become increasingly difcult as this clearance
is reduced.
2) If listed Type L vent is used, follow vent pipe manufacturer recommendations for minimum clearances.
3) Do not install this boiler directly on a combustible surface. Where it is desired to install the TWZ over a non-carpeted
combustible surface, install the boiler on the base shown in Figure 3.
4) Do not install this boiler in a location where gasoline or other ammable 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.
WARNING
FAILURE TO OBSERVE THE FOLLOWING LOCATION REQUIREMENTS COULD RESULT
IN PROPERTY DAMAGE, A FIRE, EXPLOSION OR CARBON MONOXIDE (CO) HAZARD.

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FIGURE 2: CLEARANCES
FIGURE 3: INSTALLATION OVER A COMBUSTIBLE FLOOR

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V Air for Combustion and Ventilation
Sufcient fresh air must be supplied for combustion and ventilation. Provisions for combustion and ventilation air for oil
burning equipment must be made in accordance with Section 1.5, Air for Combustion and Ventilation, in the latest edition of
Installation of Oil Burning Equipment (ANSI/NFPA 31).
To ensure an adequate supply of air for combustion, ventilation and ue gas dilution, start by determining whether the
boiler is to be installed in a building of unusually tight construction. A building of unusually tight construction can be dened
as one having 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
oors, 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 conned space - A conned space is dened 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
conned 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.
b. Find the volume of the room in cubic feet. The volume of the room in cubic feet is:
Length (ft) x width (ft) x ceiling height (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 conned space.
Example:
A TWZ090 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:
Input of TWZ090 = 0.90 Gal/hr x 140000 BTU/Gal = 126000 BTU/hr
Total input in thousands of BTU/hr = (126000 BTU/hr + 30000 BTU/hr)/1000 = 156
Volume of room = 6.25 ft x 7 ft x 8 ft = 350 ft3
350/156 = 2.24. Since 2.24 is less than 50, the boiler room is a conned space.
WARNING
• INSUFFICIENTCOMBUSTIONAIRSUPPLYMAYRESULTINTHEPRODUCTIONAND 
RELEASE OF SOOT OR DEADLY CARBON MONOXIDE (CO) INTO THE HOME WHICH CAN
CAUSE PROPERTY DAMAGE, SEVERE PERSONAL INJURY OR DEATH.
• THISBOILERISNOTDESIGNEDFORUSEINASPACETHATISDEPRESSURIZED 
RELATIVE TO THE OUTDOORS. OPERATING THIS BOILER IN A DEPRESSURIZED SPACE
MAY CAUSE PROPERTY DAMAGE, SEVERE PERSONAL INJURY OR DEATH.

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FIGURE 4: BOILER INSTALLED IN CONFINED SPACE,
ALL AIR FROM INSIDE
2) Unconned Space - Natural inltration into the boiler room will normally provide adequate air for combustion and venti-
lation without additional louvers or openings into boiler room.
3) Conned Space - Provide two openings into the boiler room, one near the oor 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 oor
(Figure 4).
• Each opening must have a free area of 1 square inch per 1000 BTU/hr input of all fuel 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 ner than ¼” (4 x 4) mesh.
For Buildings of Unusually Tight Construction:
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 oor.
3) Size openings and ducts as follows:
• Vertical ducts or openings directly outdoors (Figure 5, Figure 6, and Figure 7) - Each opening must have a free
cross sectional area of 1 square inch per 4000 BTU/hr of the total input of all fuel red 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 8) - Each opening must have a free cross sectional area of 1
square inch per 2000 BTU/hr of the total input of all fuel red 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 ner than ¼” (4 x 4) mesh.

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FIGURE 5: ALL AIR FROM OUTDOORS,
VENTILATED CRAWL SPACE AND ATTIC
FIGURE 6: ALL AIR FROM OUTDOORS,
VIA VENTILATED ATTIC

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FIGURE 7: ALL AIR FROM OUTDOORS, USING
OPENINGS INTO BOILER ROOM
FIGURE 8: ALL AIR FROM OUTDOORS, USING
HORIZONTAL DUCTS INTO BOILER ROOM

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VI Venting
Vent installation must be in accordance with local building codes, or the local authority having jurisdiction.
Typical vent installation is illustrated by Figure 9. The components of vent installation are the vent connector (breeching),
barometric draft regulator, and chimney.
1) Acceptable Chimneys - The following chimneys may be used to vent a TWZ series boiler:
• Listed Type L 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 latest edition of 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 a TWZ series boiler into an unlined chimney.
FIGURE 9: TYPICAL VENT SYSTEM
INSTALLATION AND COMPONENTS
WARNING
• IMPROPERVENTINGMAYRESULTINPROPERTYDAMAGEAND/ORTHERELEASEOF
FLUE GASES, WHICH CONTAIN DEADLY CARBON MONOXIDE (CO), INTO THE HOME,
WHICH CAN CAUSE SEVERE PERSONAL INJURY OR DEATH.
• INSPECTEXISTINGCHIMNEYBEFOREINSTALLINGBOILER.FAILURETOCLEANOR
REPLACE DAMAGED PIPE OR TILE LINING WILL CAUSE PROPERTY DAMAGE, SEVERE
PERSONAL INJURY OR DEATH.

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2) Acceptable Vent Connectors - The following may be used for vent connectors:
• Listed Type L vent.
• Single Wall Galvanized Pipe - Use 0.018” (26 gauge) or heavier.
3) Chimney and Vent Connector Sizing - See Table 2 for minimum vent connector and chimney sizing. The vent connector
size must not be smaller than boiler ue collar diameter.
4) Do not vent this appliance into any portion of a mechanical vent system operating under positive pressure.
5) Do not connect the boiler into a chimney ue serving an open replace or other solid fuel appliance.
6) Prior to boiler installation, inspect chimney for obstructions or other defects and correct as required. Clean chimney as
necessary.
7) Vent pipe should slope upward from boiler 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.
8) 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 (7) above.
9) Vent pipe should be installed above the bottom of the chimney to prevent blockage.
10) Vent pipe must be inserted ush with inside face of the chimney liner and the space between vent pipe and chimney
sealed tight. A thimble permanently cemented in place can be used to facilitate removal of chimney connector for cleaning.
11) Install the barometric draft regulator in accordance with the regulator manufacturer’s instructions.
12) Secure all joints in the vent connector system with sheet metal screws. This includes the joint between the vent
connector and the boiler collar, as well as the barometric draft regulator. Use at least three screws at each joint.
Power (“Side Wall”) Venting - Important Note
Two problems arise when any oil-red appliance is power vented:
1. There is sometimes an accelerated rate of soot buildup on the oil burner cad-cell, spinner etc.
2. There is a potential for severe damage to the side of the structure in the event that the boiler operates at a high smoke
level. This can happen for many reasons, some of which are out of the control of both the installer and appliance
manufacturer.
Crown Boiler Company recommends the use of a chimney to vent the TWZ series boilers. If a power venter must be used, it
is the responsibility of the installer and power vent manufacturer to “engineer” the power vent system. CROWN BOILER
COMPANY WILL ASSUME NO RESPONSIBILITY FOR DAMAGE TO SIDING, ETC. FROM A POWER
VENTED OIL-FIRED BOILER. THIS APPLIES REGARDLESS OF THE CAUSE OF THE SOOTING.
TABLE 2: MINIMUM RECOMMENDED BREECHING AND
CHIMNEY SIZE
Round I.D. (in) Rectangular I.D. (in) Height (ft)
TWZ065 6 6 8 x 8 15
TWZ075 6 6 8 x 8 15
TWZ100 6 6 8 x 8 15
TWZ090 7 7 8 x 8 15
TWZ125 7 7 8 x 8 15
TWZ150 7 7 8 x 8 15
TWZ120 8 8 8 x 8 15
TWZ175 8 8 8 x 8 15
TWZ200 8 8 8 x 8 15
Boiler
Model
Min Breeching
Dia. (inches)
Min. Recommended Chimney Size and Height

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FIGURE 10: STANDARD BOILER PIPING
Standard Piping
Figure 10 shows typical boiler system connections on a single zone system. Additional information on hydronic system
design may be found in the I=B=R Guide RHH published by the Air-Conditioning, Heating and Refrigeration Institute
(AHRI). The components in this system and their purposes are as follows:
VII System Piping
WARNING
• INSTALLBOILERSOTHATTHEELECTRICAL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.
• PIPERELIEFVALVEDISCHARGETOASAFELOCATION.THERELIEFVALVE
MAY DISCHARGE SCALDING HOT WATER.
• 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.BLOCKINGTHERELIEFVALVEMAY
RESULT IN BOILER EXPLOSION.

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1) Relief valve (Required) - Mount the relief valve on the top left side of the boiler as shown in Figure 10 using the 3/4”
nipple 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 oor. 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) - Figure 10 shows the ideal location of the circulator which is in the supply piping immediately
downstream of the expansion tank. A less ideal, but acceptable, location for most residential circulators is in the return (if
this is done, be sure that adequate clearance exists to open the door.
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 ll valve may be used. The ideal location for the ll 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 ll.
6) Low Water Cut-Off (Required in some situations) - A low water cut-off is required when the boiler is installed above
radiation. In addition, some codes such as ASME CSD-1, require low water cut-offs. Codes may also require that this
low water cut-off have a manual reset function. The low water cut-off may be a oat type or probe type, but must be
designed for use in a hot-water system. The low water cut-off should be piped into the boiler supply just above the boiler
with no intervening valves between it and the boiler.
Use a low water cut-off that breaks the 120 VAC supply to the boiler. Do not attempt to wire a 24-volt low water cut-off
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 ow control valve prevents ow through the system unless
the circulator is operating. A ow control valve may be necessary on converted gravity systems to prevent gravity
circulation. Flow control valves are also used to prevent “ghost ows” 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 rell the entire system.
10) Drain Valve - The drain valve is shipped in the boiler parts bag. Install it in the tee on the boiler return as shown in
Figure 1.
IMPORTANT
THE 1 1/2” PLUGGED TAPPING ON THE BOTTOM REAR SECTION IS
PRESENT FOR MANUFACTURING PURPOSES ONLY. DO NOT ATTEMPT
TO USE THIS TAPPING AS A RETURN CONNECTION.

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FIGURE 12: BOILER BYPASS PIPING
FIGURE 11: INDIRECT WATER HEATER BOILER SIDE PIPING
Piping for Special Situations
Certain types of heating systems have additional requirements. Some of the more common variations follow:
1) Indirect Water Heaters - Figure 11 shows typical indirect water heater piping. Boiler piping is the same as for any two-
zone system. Figure 11 shows circulator zoning, which is usually preferred for indirect water heaters. Size the circulator
and indirect water heater piping to obtain the boiler water ow through the indirect water heater called for by the indirect
water heater manufacturer.
2) Large Water Volume Systems - The piping shown in Figure 12 will minimize the amount of time that the boiler operates
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 rst few minutes of operation. A three-way valve can
be substituted for the two throttling valves shown.

15
FIGURE 13: ISOLATION OF BOILER FROM SYSTEM
WITH A HEAT EXCHANGER
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 TWZ. These systems also typically have return
temperatures well below the 120°F minimum.
Figure 13 illustrates the use of a heat exchanger to connect the TWZ 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 ow 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
ll 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 TWZ such as four
way mixing valves 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 TWZ. 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 13.
Consult the heat exchanger manufacturer for proper heat exchanger sizing as well as ow 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.
5) Air Handlers - Where the boiler is connected to air handlers through which refrigerated air passes, use ow control valves
in the boiler piping or other automatic means to prevent gravity circulation during the cooling cycle.

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2) Flow Restrictor (Recommended) - If water is drawn from the tankless coil at a rate in excess of the rating in Table 1b,
the temperature of the hot water may be too low to be of use. The use of a ow restrictor will prevent this problem by
limiting the rate at which water can pass through the tankless heater. If a restrictor is used, select one having a rating
in GPM approximately equal to the rating shown in Table 1b. If possible, locate this restrictor at least 3 feet from the
tankless heater inlet so that it is not subjected to excessive temperatures when no water is owing through the coil.
3) Pressure Relief Valve (Required) - Limits the pressure in the tankless heater and piping. Use an ASME constructed valve
designed for domestic water service, such as the Watts #3L. Note that this is a pressure relief valve, not a T&P valve.
Select a valve with a pressure setting less than or equal to the working pressure marked on the tankless coil. Pipe the
discharge to a safe location using piping the same size as the discharge connection on the valve.
4) Hose Bib Valves (Recommended) - These valves permit the coil to be periodically “backushed” to remove sediment.
5) Globe or Ball Valve (Recommended) - Used to adjust the ow through the entire tankless heater system if needed.
6) Unions (Required) - Tankless heaters may require periodic gasket replacement or other maintenance which requires
removal of the heater from the boiler. Install unions anywhere in the tankless heater piping that will facilitate removal of
the heater.
VIII TANKLESS HEATER PIPING
If the TWZ is installed with an optional tankless heater, pipe the heater as shown in Figure 14. The components in this
system and their functions are as follows:
1) Mixing Valve (Required) - During the heating season, the water exiting the tankless heater may be 180 degrees or more.
The mixing valve blends hot water leaving the tankless heater with cold water so as to maintain the hot water supplied
to the xtures at a xed temperature. This saves energy, increases the amount of usable hot water available to the
homeowner, and reduces the risk of scalding.
Install a mixing valve with a setting range of approximately 110 to 130F. Follow the manufacturer’s instructions for
installing this valve. Usually a “heat trap” will be required between the coil and the “hot” connection on the mixing valve.
WARNING
A MIXING VALVE DOES NOT ELIMINATE THE RISK OF SCALDING.
• SETTHEMIXINGVALVEANDBOILERLOWLIMITADJUSTMENTSASLOW 
AS POSSIBLE.
• FEELWATERBEFORESHOWERINGORBATHING.
• IF ANTI-SCALD OR ANTI-CHILL PROTECTION IS REQUIRED, USE DEVICES
SPECIFICALLY DESIGNED FOR SUCH SERVICE. INSTALL AND MAINTAIN
THESE DEVICES IN ACCORDANCE WITH THE MANUFACTURER’S
INSTRUCTIONS. DO NOT USE THE MIXING VALVE AS A SUBSTITUTE
FOR PRESSURE BALANCING VALVES OR OTHER DEVICES REQUIRED BY
PLUMBING CODES TO PROTECT AGAINST SCALDING.

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FIGURE 14: TANKLESS HEATER PIPING
IX Fuel Line Piping
WARNING
• UNDERNOCIRCUMSTANCESCANCOPPERWITHSWEATSTYLECONNECTORS
BE USED.
• DONOTUSECOMPRESSIONFITTINGS.
• OILPIPINGMUSTBEABSOLUTELYAIRTIGHTORLEAKSORLOSSOFPRIME
MAY RESULT.
• SOMEJURISDICTIONSREQUIRETHEUSEOFAFUSIBLESHUTOFFVALVEAT
THE TANK AND/OR THE BURNER. IN ADDITION, SOME JURISDICTIONS REQUIRE
THE USE OF A FUSIBLE ELECTRICAL INTERLOCK WITH THE BURNER CIRCUIT.
CHECK YOUR LOCAL CODES FOR SPECIAL REQUIREMENTS.
Fuel line piping design, materials and construction must be in accordance with local building codes, requirements of the lo-
cal authority having jurisdiction, and, the latest edition of the Standard for the Installation of Oil-Burning Equipment (ANSI/
NFPA 31) in the United States and CSA B139-04 for installation in Canada. Refer also to the instruction manuals provided
with the burner and oil pump.

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Depending on the location of the fuel oil storage tank in relation to an oil burner, there are four types of oil piping systems
generally being used:
a) ONE-PIPE GRAVITY SYSTEM - used when a fuel oil storage tank is positioned above an oil burner fuel pump. See
Figure 15. A vertical distance from top of the tank to center line of the pump (Dimension ‘H’) over 8 feet will result in
a pump inlet pressure in excess of the 3-psi limit in NFPA-31.
b) ONE-PIPE LIFT SYSTEM (not recommended) - Used when a fuel oil storage tank is located below an oil burner fuel
pump. See Figure 16. The vertical distance from bottom of the tank to center line of the pump (Dimension ‘H’) must
not exceed that shown in the pump manufacturer’s instructions. Although all oil piping systems must be airtight, one-
pipe lift systems are particularly susceptible to nuisance lockout problems if the suction line is not completely airtight.
A two-pipe lift system is therefore recommended over a one-pipe lift system.
c) TWO-PIPE GRAVITY SYSTEM (not recommended) - Used when a fuel oil storage tank is located above an oil
burner fuel pump. See Figure 17. A vertical distance from top of the tank to center line of the pump (Dimension ‘H’)
over 8 feet will result in a pump inlet pressure in excess of the 3-psi limit in NFPA-31. This type of system should be
converted to a one-pipe gravity system, as doing so will result in lower inlet line ow and longer lter life.
d) TWO-PIPE LIFT SYSTEM - used when a fuel oil storage tank is located below an oil burner fuel pump suction port.
See Figure 18. The vertical distance from bottom of the tank to center line of the pump (Dimension ‘H’) must not
exceed that shown in the pump manufacturer’s instructions. Distance ‘H’ allowed is reduced by the number of ttings,
lters and valves installed in the line.
Once the type of system has been selected, observe the following:
1) Fuel line piping must be airtight. Do not use compression type ttings for tubing connections in fuel line piping. Use
only listed are type ttings. Cast iron threaded ttings shall not be used.
2) Piping shall be substantially supported and protected against physical damage and corrosion where required.
3) Refer to supplied oil pump instruction manual for proper connections. On one-pipe systems, ensure that the fuel pump
return port plug is tightened securely.
4) Some fuel pumps, such as the Suntec A and B series, are supplied with a loose bypass plug which must be installed on
two-pipe systems. If such a plug is supplied, install it as shown in the pump manufacturer’s instructions. Do not install this
bypass plug on one-pipe systems as pump seal damage will result.
5) Do not use check valves, especially on gravity feed systems.
6) Do not use Teon tape for threaded connections. Use a listed non-hardening thread sealant instead.
FIGURE 15: ONE-PIPE GRAVITY SYSTEM