Lennox ML180UHT Installation Instructions Manual

Page 1
INSTALLATION
2015 Lennox Industries Inc.
Dallas, Texas, USA
AIR FLOW
UPFLOW
INSTRUCTIONS ML180UHT
MERIT® SERIES GAS FURNACE UPFLOW / HORIZONTAL AIR DISCHARGE
507408-01 06/2015 Supersedes 507061-01
THIS MANUAL MUST BE LEFT WITH THE
HOMEOWNER FOR FUTURE REFERENCE
This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in manuals, be alert to the potential for personal injury or death.
WARNING
Improper installation, adjustment, alteration, service or maintenance can cause property damage, person al injury or loss of life. Installation and service must be performed by a licensed professional installer (or equivalent), service agency or the gas supplier.
Litho U.S.A.
AIR FLOW
AIR FLOW
HORIZONTAL LEFT
HORIZONTAL RIGHT
Los calefactores están aprobados por el Instituto del Gas Argentino (IGA) para funcionar con gas natural y no se pueden convertir para funcionar con gas licuado.
Table of Contents
Unit Dimensions 2................................
ML180UHT Gas Furnace 3.........................
Shipping and Packing List 3........................
Requirements 3...............................
General 4........................................
Combustion, Dilution & Ventilation Air 4..............
Setting Equipment 7...............................
Filters 11..........................................
Duct System 11....................................
Venting 12........................................
CAUTION
As with any mechanical equipment, personal injury can result from contact with sharp sheet metal edges. Be careful when you handle this equipment.
Gas Piping 19.....................................
Electrical 21.......................................
Integrated Control 22...............................
Unit Start-Up 24...................................
Gas Pressure Adjustment 25........................
Proper Combustion 25..............................
High Altitude 26....................................
Other Unit Adjustments 26..........................
Service 27........................................
Repair Parts 28...................................
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Page 2
Unit Dimensions - mm
1
NOTE - 60C and 60D units that require air volumes
over 1800 cfm (850 L/s) must have one of the following:
1. Single side return air with transition to accommodate 508 x 635 x 25 mm cleanable air filter. (Required to maintain proper air velocity.)
2. Single side return with optional return air base.
3. Bottom return air.
4. Return air from both sides.
5. Bottom and one side return air.
See Blower Performance Tables for additional informa tion.
2
Flue outlet may be horizontal but furnace must be
vented vertically
3
Optional external side return air filter kit cannot be used
with the optional RAB Return Air Base.
D
FLUE OUTLET
(Top)
3
OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
79
SUPPLY AIR
OPENING
603
635
TOP VIEW
19
A
B
C
1
Bottom Return
Air Opening
FRONT VIEW
14
3
OPTIONAL
EXTERNAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
375
406
16
19
838
19
Front Panel
76 Right
171 Left
232 Right
219 Left
137 Right
40 Left
ELECTRICAL INLET (Either Side)
(Either Side)
83
38
83
2
FLUE OUTLET
(Either Side)
GAS PIPING INLET
(Either Side)
1
Side Return Air Opening (Either Side)
1
Bottom Return
Air Opening
SIDE VIEW
584
597
705
494
14
38
356
49
ML180UHT Model No.
070TP36A
090TP48B
110TP36C 110TP60C
135TP60D
A B C D
mm mm mm mm
368 340 330 121
446 416 406 159
533 504 495 203
622 546 584 248
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ML180UHT Gas Furnace
The ML180UHT unit is shipped ready for installation in the upflow or horizontal right position (for horizontal left posi tion the combustion air pressure switch must be moved). The furnace is shipped with the bottom panel in place. The bottom panel must be removed if the unit is to be installed in a horizontal application. The panel may also be removed in upflow applications with bottom return air.
Shipping and Packing List
Package 1 of 1 contains
1 - Assembled ML180UHT unit 1 - Bag assembly containing the following:
2 - Screws 1 - Snap bushing 1 - Snap plug 1 - Wire tie 1 - Vent warning label 1 - Owner's manual
The following items may be ordered separately: 1 - Thermostat 1 - Suspension kit (for horizontal installations) 1 - Propane/LP changeover kit 1 - Return air base 1 - High altitude kit 1 - Side filter kit
Check equipment for shipping damage. If you find any damage, immediately contact the last carrier.
Requirements
The ML180UHT furnace is approved for installation for in side of building only, with clearances as listed in figure 6. (Accessibility and service clearances must take prece dence over fire protection clearances). Installation of Len nox forced air central furnaces must be in accordance with these instructions, local gas fitting regulations, municipal building codes and electrical wiring regulations
The acceptable natural gas Wobbe number values for use with Lennox furnaces are shown in Table 1.
TABLE 1
Wobbe
Number*
Gas Properties 101.3 kPa, 15° C Dry bulb
* Wobbe number = heating value square root of specific gravity
Min Normal Max
46.95 mj / m
(1260 Btu / ft3)
(14.73 psia, 60° F Dry Bulb)
3
50.15 mj / m
(1346 Btu / ft3)
3
53.28 mj / m
(1430 Btu / ft3)
3
If you need to know whether a gas is acceptable, request the Wobbe number from your gas supplier and compare to the chart. If the number is within the ranges listed for Natu ral gas, the gas is acceptable to use. If the Wobbe number is outside the acceptable ranges, the gas is not acceptable to use. As LP (Propane) is a regulated/manufactured gas, a Wobbe number is not required to determine acceptability. For propane installations, the acceptable heating value range is 93.2 mj / m
3
(2500 btu/ft3) +/- 5%.
NOTE - Lennox does not recommend using unrefined or ”well head” gas on Lennox gas-fired furnaces. The quality of gas is not controlled and may have contaminants which may lead to corrosion, premature heat exchanger failure or may void the equipment warranty. The information pro vided above is intended for evaluating fuel gases available commercially through gas utilities or LP (propane) suppli ers.
Adequate clearance must be made around the air open ings into the vestibule area. Provisions shall be made for proper operation and for combustion air and ventilation air supply according to local codes or these instructions.
NOTE - For installation on combustible floors, the furnace shall not be installed directly on carpeting, tile, or other combustible material other than wood flooring.
For installation in a residential garage, the furnace must be installed so that the burner(s) and the ignition source are located no less than 457 mm (18 in) above the floor. The furnace must be located or protected to avoid physical damage by vehicles. When a furnace is installed in a public garage, hangar, or other building that has a hazardous at mosphere, the furnace must be installed according to local codes.
Unit must be adjusted to obtain a temperature rise within the range specified on appliance rating plate.
This ML180UHT furnace must be installed so that its elec trical components are protected from water.
When this furnace is used with cooling units, it shall be installed in parallel with, or on the upstream side of, cooling units to avoid condensation in the heating compartment. With a parallel flow arrangement, a damper (or other means to control the flow of air) must adequately prevent chilled air from entering the furnace. If the damper is manu ally operated, it must be equipped to prevent operation of either the heating or the cooling unit, unless it is in the full
HEAT or COOL setting.
When installed, this furnace must be electrically grounded according to local codes.
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All field wiring must comply with local codes or what is listed in these instructions.
When furnace is installed so that supply ducts carry air cir culated by furnace to areas outside of space containing ufurnace, return air shall be handled by a duct(s) sealed to a furnace casing and terminating outside space containing furnace.
NOTE - ML180UHT series units must not be used as a “construction heater” during any phase of construction. Very low temperatures, harmful vapors and misplacement of the filters will damage the unit and its efficiency.
The ML180UHT furnace may be installed in alcoves, clos ets, attics, basements, garages, crawl spaces and utility rooms in any of its approved installation positions.
This furnace design has not been approved for instal lation in mobile homes, recreational vehicles, or out doors.
WARNING
The blower access panel must be securely in place when the blower and burners are operating. Gas fumes, which could contain carbon monoxide, can be drawn into living space resulting in personal inju ry or death.
General
These instructions are intended as a general guide and do not supersede local codes in any way. Consult au thorities having jurisdiction before installation.
In addition to the requirements outlined previously, the fol lowing general recommendations must be considered when installing a ML180UHT furnace:
Place the furnace as close to the center of the air dis
tribution system as possible. The furnace should also be located close to the chimney or vent termination point.
Do not install the furnace where drafts might blow direct
ly into it. This could cause improper combustion and un safe operation.
Do not block the furnace combustion air openings with
clothing, boxes, doors, etc. Air is needed for proper combustion and safe unit operation.
When the furnace is installed in an attic or other insu
lated space, keep insulation away from the furnace.
WARNING
The State of California has determined that this prod uct may contain or produce a chemical or chemicals, in very low doses, which may cause serious illness or death. It may also cause cancer, birth defects or reproductive harm.
Combustion, Dilution & Ventilation Air
In the past, there was no problem in bringing in sufficient outdoor air for combustion. Infiltration provided all the air that was needed. In today's homes, tight construction prac tices make it necessary to bring in air from outside for com bustion. Take into account that exhaust fans, appliance vents, chimneys, and fireplaces force additional air that could be used for combustion out of the house. Unless out side air is brought into the house for combustion, negative pressure (outside pressure is greater than inside pressure) will build to the point that a downdraft can occur in the fur nace vent pipe or chimney. As a result, combustion gases enter the living space creating a potentially dangerous situ ation.
CAUTION
Do not install the furnace in a corrosive or contami nated atmosphere. Meet all combustion and ventila tion air requirements, as well as all local codes.
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CAUTION
Insufficient combustion air can cause headaches, nausea, dizziness or asphyxiation. It will also cause excess water in the heat exchanger resulting in rust ing and premature heat exchanger failure. Excessive exposure to contaminated combustion air will result in safety and performance related problems. Avoid exposure to the following substances in the com bustion air supply:
Permanent wave solutions Chlorinated waxes and cleaners Chlorine base swimming pool chemicals Water softening chemicals De‐icing salts or chemicals Carbon tetrachloride Halogen type refrigerants Cleaning solvents (such as perchloroethylene) Printing inks, paint removers, varnishes, etc. Hydrochloric acid Cements and glues Antistatic fabric softeners for clothes dryers Masonry acid washing materials
All gas‐fired appliances require air for the combustion pro cess. If sufficient combustion air is not available, the fur nace or other appliances will operate inefficiently and un safely. Enough air must be provided to meet the needs of all fuel‐burning appliances and appliances such as ex haust fans which force air out of the house. When fire places, exhaust fans, or clothes dryers are used at the same time as the furnace, much more air is necessary to ensure proper combustion and to prevent a downdraft. In sufficient air causes incomplete combustion which can re sult in carbon monoxide.
In addition to providing combustion air, fresh outdoor air di lutes contaminants in the indoor air. These contaminants may include bleaches, adhesives, detergents, solvents and other contaminants which can corrode furnace compo nents.
The requirements for providing air for combustion and ven tilation depend largely on whether the furnace is installed in an unconfined or a confined space.
Unconfined Space
An unconfined space is an area such as a basement or large equipment room with a volume greater than 1.42 m (50 cubic feet) per .29 kW (1,000 Btu) per hour of the com bined input rating of all appliances installed in that space. This space also includes adjacent rooms which are not separated by a door. Though an area may appear to be un confined, it might be necessary to bring in outdoor air for combustion if the structure does not provide enough air by infiltration. If the furnace is located in a building of tight construction with weather stripping and caulking around the windows and doors, follow the procedures in the air from outside section.
Confined Space
A confined space is an area with a volume less than 1.42
3
m
(50 cubic feet) per .29 kW (1,000 Btu) per hour of the combined input rating of all appliances installed in that space. This definition includes furnace closets or small equipment rooms.
When the furnace is installed so that supply ducts carry air circulated by the furnace to areas outside the space con taining the furnace, the return air must be handled by ducts which are sealed to the furnace casing and which terminate outside the space containing the furnace. This is especially important when the furnace is mounted on a platform in a confined space such as a closet or small equipment room. Even a small leak around the base of the unit at the platform or at the return air duct connection can cause a potentially dangerous negative pressure condition. Air for combustion and ventilation can be brought into the confined space ei ther from inside the building or from outside.
EQUIPMENT IN CONFINED
SPACE ALL AIR FROM INSIDE
CHIMNEY
OR GAS
VENT
WATER
FURNACE
NOTE - Each opening shall have a free area of at least 645 mm square inch) per .29 kW (1,000 Btu) per hour of the total input rating of all equipment in the enclosure, but not less than 64516 mm square inches).
HEATER
OPENINGS
(To Adjacent
FIGURE 1
Air from Inside
If the confined space that houses the furnace adjoins a space categorized as unconfined, air can be brought in by providing two permanent openings between the two
3
spaces. Each opening must have a minimum free area of 645 mm
2
(1 square inch) per .29 kW (1,000 Btu) per hour of total input rating of all gas-fired equipment in the confined space. Each opening must be at least 64516 mm square inches). One opening shall be within 305 mm (12 inches) of the top of the enclosure and one opening within 305 mm (12 inches) of the bottom. See figure 1.
Air from Outside
If air from outside is brought in for combustion and ventila tion, the confined space must have two permanent open ings. One opening shall be within 305 mm (12 inches) of the
Room)
2 (
one
2
1(00
2
(100
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top of the enclosure and one opening within 305 mm (12 inches) of the bottom. These openings must communicate directly or by ducts with the outdoors or spaces (crawl or attic) that freely communicate with the outdoors or indirect ly through vertical ducts. Each opening shall have a mini mum free area of 645 mm
2
(1 square inch) per 1.17 kW
(4,000 Btu) per hour of total input rating of all equipment in the enclosure. See figures 2 and 3. When communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of 645 mm
2
(1 square inch)
per .56 kW (2,000 Btu) per total input rating of all equipment in the enclosure. See figure 4.
When ducts are used, they shall be of the same cross-sec
(Inlet Air from Crawlspace and Outlet Air to Ventilated Attic)
CHIMNEY OR
GAS VENT
VENTILATION LOUVERS
(Each end of attic)
tional area as the free area of the openings to which they connect. The minimum dimension of rectangular air ducts shall be no less than 75 mm (3 inches). In calculating free area, the blocking effect of louvers, grilles, or screens must be considered. If the design and free area of protective cov ering is not known for calculating the size opening required, it may be assumed that wood louvers will have 20 to 25 per cent free area and metal louvers and grilles will have 60 to 75 percent free area. Louvers and grilles must be fixed in the open position or interlocked with the equipment so that they are opened automatically during equipment opera tion.
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
OUTLET
FURNACE
VENTILATION
LOUVERS
(For unheated crawl space)
NOTE-The inlet and outlet air openings shall each have a free area of at least 645 mm square inch) per 1.17 kW (4,000 Btu) per hour of the total input rating of all equipment in the enclo sure.
AIR
WATER
HEATER
INLET
AIR
2
(one
FIGURE 2
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CHIMNEY
OR GAS
VENT
FURNACE
EQUIPMENT IN CONFINED SPACE
ALL AIR FROM OUTSIDE
(All Air Through Ventilated Attic)
VENTILATION LOUVERS
(Each end of attic)
OUTLET
AIR
INLET AIR
(Ends 12 in.
above bottom)
NOTE - As an option, rubberlike pads defined as having an elastic texture resembling rubber in flexibility or toughness, may be placed under each corner of the furnace as ap propriate to the application.
The ML180UHT gas furnace can be installed as shipped in either the upflow position or the horizontal position.
Select a location that allows for the required clearances that are listed on the unit nameplate. Also consider gas supply connections, electrical supply, vent connection, and installation and service clearances [610 mm (24 inches)] at unit front. The unit must be level.
WATER
HEATER
NOTE-The inlet and outlet air openings shall each have a free area of at least 645 mm kW (4,000 Btu) per hour of the total input rating of all equipment in the enclosure.
2 (
one square inch) per 1.17
FIGURE 3
EQUIPMENT IN
CONFINED SPACE
ALL AIR FROM
OUTSIDE
OUTLET AIR
INLET AIR
FURNACE
CHIMNEY
OR GAS
VENT
WATER
HEATER
NOTE - Units with 1/2 hp blower motors (ML180UH110TP36C and ML180UH090TP48B)are equipped with three flexible legs and one rigid leg. See fig ure 5. The rigid leg is equipped with a shipping bolt and a flat white plastic washer (rather than the rubber mounting grommet used with a flexible mounting leg). The bolt and
washer must be removed before the furnace is placed into operation. After the bolt and washer have been re
moved, the rigid leg will not touch the blower housing.
NOTE - ML180UH090TP48B, & ML180UH110TP36C are also equipped with a shipping pad under the blower housing. Remove the shipping pad prior to operation.
ML180UH110TP36C and
ML180UH090TP48B with 1/2 HP
BLOWER MOTOR
RIGID LEG
remove shipping bolt and washer
NOTE - Each air duct opening shall have a free area of at least 645
2 (
mm
one square inch) per .59 kW (2,000 Btu) per hour of the total input rating of all equipment in the enclosure. If the equipment room is located against an outside wall and the air openings communi cate directly with the outdoors, each opening shall have a free area of at least 645 mm hour of the total input rating of all other equipment in the enclosure.
2
(one square inch) per 1.17 kW (4,000 Btu) per
FIGURE 4
Setting Equipment
WARNING
Do not install the furnace on its front or its back. Do not connect the return air ducts to the back of the fur nace. Doing so will adversely affect the operation of the safety control devices, which could result in per sonal injury or death.
FIGURE 5
CAUTION
If this unit is being installed in a space serviced by an exhaust fan, power exhaust fan, or other device which may create a negative pressure in the space, take care when sizing the inlet air opening. The in let air opening must be sized to accommodate the maximum volume of exhausted air as well as the maximum volume of combustion air required for all gas appliances serviced by this space.
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Upflow Applications
Allow for clearances to combustible materials as indicated on the unit nameplate. Minimum clearances for closet or al cove installations are shown in figure 6.
Upflow Application Installation Clearances
Top
Left Side
Bottom
Type of Vent
Connector
Top 25 mm (in.) 25 mm (1 in.)
*Front 57 mm (2-1/4 in)** 57 mm (2-1/4 in.)
Back 0 0
Sides 0 0
Vent 152 mm (6 in.) 25 mm (1 in.)
Floor 0 0
*Front clearance in alcove installation must be 610 mm (24 in.). Maintain a minimum of 610 (24 in.) mm for front service access. ** 114 mm (4-1/2 in.) if single wall vent pipe is used. For installation on a combustible floor, do not install the furnace directly on carpeting, tile or other combustible materials other than wood flooring. Left side requires 76 mm (3 in.) if a single wall vent is used on 368 mm (14-1/2 in.) cabinets, or 51 mm (2 in.) if a single wall vent pipe is used on 445 mm (17-1/2 in.) cabinets.
Type C Type B1
Right Side
FIGURE 6
Return Air - Upflow Applications
Return air can be brought in through the bottom or either side of the furnace installed in an upflow application. If the furnace is installed on a platform with bottom return, make an airtight seal between the bottom of the furnace and the platform to ensure that the furnace operates properly and safely. The furnace is equipped with a removable bottom
panel to facilitate installation.
Markings are provided on both sides of the furnace cabinet for installations that require side return air. Cut the furnace cabinet at the maximum dimensions shown on page 2.
NOTE -
L/s (1800cfm) must have one of the following:
1 - Single side return air with transition to accommodate
2 - Single side return air with optional return airbase. See
3 - Bottom return air.
4 - Return air from both sides.
5 - Bottom and one side return air.
60C and 60D units that require air volumes over 850
508 x 635 x 25 mm (20 x 25 x 1 in.) cleanable air filter. (Re quired to maintain proper air velocity.) See figure 7.
figure 8.
Refer to Product Specifications bulletin for additional infor mation.
Single Side Return Air
(with transition and filter)
508mm X 635mm X 25mm (20” X 25” X 1”)
Cleanable Filter
Return Air
Plenum
AIR FLOW
Transition
FIGURE 7
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Page 9
Optional Return Air Base
(Upflow Applications Only -- For use with A, B, C and D cabinets)
FURNACE
FRONT
IF BASE IS USED
INDOOR AIR QUALITY CABINET
AIR FLOW
368 (141/2) A WIDTH (65W75) 446 (171/2) B WIDTH (50W89) 533 (21) C WIDTH (50W99) 622 (241/2) D WIDTH (51W00)
NOTE- Optional Side Return Air Filter Kits are not for use with Optional Return Air Base.
1
Both the unit return air opening and the base return air opening must be covered by a single plenum or IAQ cabinet.
(PCO, FILTER CABINET, ETC
OPTIONAL RETURN AIR BASE
WITHOUT
IAQ CABINET,
A SINGLE
RETURN AIR
PLENUM
MUST
COVER BOTH
UNIT AND
RETURN
AIR BASE
OPENINGS
83 (31/4)
184 (71/4)
1
584 (26)
Overall
(Maximum)
1
Unit side return air
Opening
143
(55/8)
SIDE RETURN
AIR OPENINGS
(Either Side)
683
(267/8)
SIDE VIEW
584 (23)
1
Minimum
279 (11)
2
Maximum
356 (14)
Minimum unit side return air opening dimensions for units requiring 850 L/s (1800 cfm) or more of air (W x H): 584 x 279
mm. (23 X 11 in.)
The opening can be cut as needed to accommodate plenum or IAQ cabinet while maintaining dimensions shown.
Side return air openings must be cut in the field. There are cutting guides stenciled on the cabinet for the side return air
opening. The size of the opening must not extend beyond the markings on the furnace cabinet.
2
To minimize pressure drop, the largest opening height possible [up to 356 mm (14 in.)] is preferred.
FIGURE 8
Removing the Bottom Panel
Remove the two screws that secure the bottom cap to the furnace. Pivot the bottom cap down to release the bottom panel. Once the bottom panel has been removed, reinstall the bottom cap. See figure 9.
1
570 (22)
Overall
(Maximum)
19 (3/4)
Page 9
Page 10
Removing the Bottom Panel
)
Screw
Allow for clearances to combustible materials as indicated on the unit nameplate. Minimum clearances for closet or al cove installations are shown in figure 10.
This furnace may be installed in either an attic or a crawl space. Either suspend the furnace from roof rafters or floor joists, as shown in figure 11, or install the furnace on a plat form, as shown in figure 12.
Typical Horizontal Application
Unit Suspended in Attic or Crawlspace
Metal
Internal
Bracket
Strap
Brace
4.8 mm (3/16 in
Bottom Cap
Bottom Panel
FIGURE 9
Horizontal Application
Installation Clearances
Left End
Vent Connector
Type
Top 0 0
*Front 57 mm (2-1/4 in.)** 57 mm (2-1/4 in. )
Back 0 0
Ends 51 mm (2 in.) 51 mm (2 in.)
Vent 152 mm (6 in.) 25 mm (1 in. )
Floor 0 0
*Front clearance in alcove installation must be 610 mm (24 in) Maintain a minimum of 610 mm (24 in.) for front service access. ** 114 mm (4-1/2 in.) if singlewall vent pipe is used. For installations on a combustible floor, do not install the fur nace directly on carpeting, tile or other combustible materials oth er than wood flooring.
Top
Right
AIR FLOW
End
Bottom
Type C Type B1
Air Flow
FIGURE 11
NOTE - Heavy-gauge perforated sheet metal straps may be used to suspend the unit from roof rafters or ceiling joists. When straps are used to suspend the unit in this way, support must be provided for both the ends. The straps must not interfere with the plenum or exhaust piping instal lation. Cooling coils and supply and return air plenums
must be supported separately. NOTE - When the furnace is installed on a platform in a
crawlspace, it must be elevated enough to avoid water damage and to allow the evaporator coil to drain.
Return Air -- Horizontal Applications
Return air must be brought in through the end of a furnace installed in a horizontal application. The furnace is equipped with a removable bottom panel to facilitate instal lation. See figure 9.
FIGURE 10
Horizontal Applications
The ML180UHT furnace can be installed in horizontal ap plications. Order horizontal suspension kit (51W10) from Lennox, or use equivalent suspension method.
Page 10
Page 11
Horizontal Application
Unit Installed on Platform
Line contact is permissible but not preferred
See the unit nameplate for
clearances.
GAS
ENTRY
SERVICE PLATFORM
VENT
PIPE
FIGURE 12
WARNING
Improper installation of the furnace can result in per sonal injury or death. Combustion and flue products must never be allowed to enter the return air system or the living space. Use screws and joint tape to seal the return air system to the furnace. In platform installations with bottom return air, the furnace should be sealed airtight to the return air ple num. A door must never be used as a portion of the return air duct system. The base must provide a stable support and an airtight seal to the furnace. Al low absolutely no sagging, cracks, gaps, etc. The return and supply air duct systems must never be connected to or from other heating devices such as a fireplace or stove, etc. Fire, explosion, carbon monoxide poisoning, personal injury and/or proper ty damage could result.
WARNING
The blower access panel must be securely in place when the blower and burners are operating. Gas fumes, which could contain carbon monoxide, can be drawn into living space resulting in personal inju ry or death.
Filters
This unit is not equipped with a filter or rack. A field-pro vided high-velocity filter is required for the unit to operate properly. Table 2 lists recommended filter sizes. A filter must be in place any time the unit is operating.
TABLE 2
Furnace
Cabinet
Width
A - 338
(14-1/2”)
B- 446
( 17-1/2”)
C - 533
( 21”)
D - 622
(24-1/2”)
Filter Size mm (in) and Quantity
Side Return Bottom Return
406 X 635 X 25 1
(16 X 25 X 1)
406 X 635 X 25 1
(16 X 25 X 1)
405 X 635 X 25 1
(16 X 25 X 1)
405 X 635 X 25 2
(16 X 25 X 1)
356 X 635 X 25 1
(14 X 25 X 1)
406 X 635 X 25 1
(16 X 25 X 1)
508 X 635 X 25 1
(20 X 25 X 1)
610 X 635 X 25 1
(24 X 25 X 1)
Duct System
Use industry‐approved standards to size and install the supply and return air duct system. This will result in a quiet and low‐static system that has uniform air distribution.
NOTE - Do not operate the furnace in the heating mode with an external static pressure that exceeds 0.5 inches w.c. Higher external static pressures may cause erratic lim it operation.
Supply Air Plenum
If the furnace is installed without a cooling coil, a removable access panel must be installed in the supply air duct. The access panel should be large enough to permit inspection (either by smoke or reflected light) of the heat exchanger for leaks after the furnace is installed. The furnace access panel must always be in place when the furnace is operat ing and it must not allow leaks into the supply air duct sys tem.
Return Air Plenum NOTE - Return air must not be drawn from a room
where this furnace, or any other gas-fueled appliance (i.e., water heater), or carbon monoxide producing de vice (i.e., wood fireplace) is installed.
When return air is drawn from a room, a negative pressure is created in the room. If a gas appliance is operating in a room with negative pressure, the flue products can be pulled back down the vent pipe and into the room. This re verse flow of the flue gas may result in incomplete combus tion and the formation of carbon monoxide gas. This toxic gas might then be distributed throughout the house by the furnace duct system.
In upflow applications, the return air can be brought in through the bottom or either side of the furnace. If a furnace with bottom return air is installed on a platform, make an air tight seal between the bottom of the furnace and the plat form to ensure that the unit operates properly and safely.
Page 11
Page 12
Use fiberglass sealing strips, caulking, or equivalent seal ing method between the plenum and the furnace cabinet to ensure a tight seal. If a filter is installed, size the return air duct to fit the filter frame.
Venting
The ML180UHT is a fan assisted furnace equipped with an integral mechanical means to either draw or force products of combustion through the combustion chamber and/or heat exchanger. When installed in the vertical position and vented vertically, the furnace operates with a non-positive vent stack pressure. When installed in the horizontal posi tion and vented vertically, the furnace operates with a posi tive stack pressure.
IMPORTANT
The ML180UHT is certified for horizontal installation but DO NOT vent flue horizontally. The ML180UHT furnace is not certified for horizontal venting. See figure 21.
General Venting Requirements
A 102 mm (4 in.) diameter flue transition is factory‐installed on the combustion air inducer outlet of all models. Figure
14 shows the combustion air inducer as shipped from the factory.
Mounting Screws Location
Flue Transition
Mounting Screws
Upflow Position
UPFLOW POSITION
Pressure
Switch
Top Vent Discharge
Flue
Transition
AIR
Vent Pipe
Collector Box
FLOW
FIGURE 14
IMPORTANT
The unit will not vent properly with the flue transition pointed down in the 6 o'clock position. The combustion air inducer may be rotated clock wise or counterclockwise by 90° to allow for top or side vent discharge in all applications. When the unit is installed, the flue transition must be in the 9 o'clock, 12 o'clock or 3 o'clock position.
FIGURE 13
If necessary, reposition the combustion air inducer, pres sure switch and/or make-up box as needed per the follow ing steps. See figures 14 through 20.
1 - Remove the four mounting screws (figure 13) which
secure the combustion air inducer / pressure switch assembly to the orifice plate. Lift the inducer assembly and rotate it 90 degrees clockwise or counterclockwise to either the 3 o'clock position or to 9 o'clock position. Re-secure with four screws. Gasket should be left in place.
2 - Use tin snips to cut preferred opening on the cabinet
for repositioning the flue outlet. Use the cut-out piece as a cover plate to patch unused opening on cabinet.
UPFLOW POSITION
Left Side Vent Discharge
Pressure
Switch
Vent Pipe
Flue
Transition
FLOW
AIR
Gas supply piping must be brought into the unit from the right
side in order to accommodate the flue pipe.
Cut combustion air inducer tubing from 229 mm (9”) to 203 mm
(8”) to avoid interference with inducer motor
Collector Box
FIGURE 15
Page 12
Page 13
Collector Box
Pressure
Switch
UPFLOW POSITION
Right Side Vent Discharge
Cover Plate
Flue Transition
HORIZONTAL RIGHT POSITION
Side Vent Discharge
Pressure Switch
Vent Pipe
AIR
FLOW
Flue Transition
FLOW
AIR
Cut combustion air inducer tubing from 229 mm ( 9” ) to 127 mm
(5”) to avoid interference with inducer motor
FIGURE 16
HORIZONTAL LEFT POSITION
Vent Pipe
Pressure
Switch
Flue
Transition
Cover Plate
Disconnect pressure switch hose from barbed fitting on the
pressure switch assembly. Remove pressure switch assembly (1 screw) and cut wire tie to free pressure switch wires. Re­install pressure switch on the other side of orifice plate and re­connect pressure switch hose.
Re-secure pressure switch wires: Either pull excess wires
through the blower compartment and secure using supplied wire tie, or coil excess wire and secure to the gas manifold.
Top Vent Discharge
AIR
FLOW
Collector Box
Collector Box
FIGURE 18
HORIZONTAL LEFT POSITION
Side Vent Discharge
Pressure Switch
AIR
FLOW
Vent Pipe
Make-Up Box
Cut combustion air inducer tubing from 227 mm (9”) to
178 mm (7”) to avoid interference with inducer motor
Disconnect pressure switch hose from barbed fitting on the
pressure switch assembly. Remove pressure switch assembly (1 screw) and cut wire tie to free pressure switch wires. Re­install pressure switch on the other side of orifice plate and re­connect pressure switch hose.
Re-secure pressure switch wires: Either pull excess wires
through the blower compartment and secure using supplied wire tie, or coil excess wire and secure to the gas manifold.
Collector Box
FIGURE 17
FIGURE 19
Page 13
Page 14
HORIZONTAL RIGHT POSITION
Top Vent Discharge
Vent Pipe
Pressure Switch
Flue
Transitio
n
AIR
FLOW
Gas supply piping must be brought into the unit from the
bottom in order to accommodate the flue pipe.
Cut combustion air inducer tubing from 227 mm (9”) to 203
mm (8”) to avoid interference with inducer motor
Cover Plate
Collector Box
FIGURE 20
The ML180UHT series units are classified as fan-assisted Category I furnaces when vertically vented. according to the latest edition of National Fuel Gas Code (NFPA 54 / ANSI Z223.1) in the USA. A fan-assisted Category I fur nace is an appliance equipped with an integral mechanical means to either draw or force combustion products through the combustion chamber and/or heat exchanger. The ML180UHT is not approved for use with horizontal venting.
NOTE - Use these instructions as a guide. They do not su persede local codes. This furnace must be vented accord ing to all local codes these installation instructions, and the provided venting tables in these instructions
The venting tables in this manual were extracted from the National Fuel Gas Code (NFPA 54 / ANSI Z223.1) and are provided as a guide for proper vent installation. Proper ap plication, termination, construction and location of vents must conform to local codes having jurisdiction. In the ab sence of local codes, the NFGC serves as the defining doc ument.
Refer to the tables and the venting information contained in these instructions to properly size and install the venting system.
Use self-drilling sheet metal screws or a mechanical fas tener to firmly secure the vent pipe to the round collar of the flue transition. If self-drilling screws are used to attach the vent pipe, it is recommended that three be used. Drive one self-drilling screw through the front and one through each side of the vent pipe and collar. See figure 21.
Install the first vent connector elbow at a minimum of six inches (152 mm) from the furnace vent outlet. See figure
21.
Venting Using a Masonry Chimney
The following additional requirements apply when a lined masonry chimney is used to vent this furnace.
Masonry chimneys used to vent Category I central fur naces must be either tile‐lined or lined with a listed metal lining system or dedicated gas vent. Unlined masonry chimneys are prohibited. See figures 22 and 23 for com mon venting.
A chimney with one or more sides exposed to the outside of the structure is considered to be an exterior chimney.
An exterior masonry chimney that is not tile-lined must be lined with B1 vent or a listed insulated flexible metal vent. An exterior tile-lined chimney that is sealed and capped may be lined with a listed uninsulated flexible metal vent.
If the existing chimney will not accommodate a listed metal liner, either the chimney must be rebuilt to accommodate one of these liners or an alternate approved venting meth od must be found.
Insulation for the flexible vent pipe must be an encapsu lated fiberglass sleeve recommended by the flexible vent pipe manufacturer. See figure 22.
IMPORTANT
Once the venting system is installed, attach the “Dis connected Vent” warning sticker to a visible area of the plenum near the vent pipe. See figure 21. The warning sticker is provided in the bag assembly. Or der kit 66W04 for additional stickers.
WARNING
Asphyxiation hazard. The exhaust vent for this fur nace must be securely connected to the furnace flue transition at all times.
VENT CONNECTION UPFLOW AND HORIZONTAL POSITION
VENT PIPE
(min. 6” length)
FLUE
TRANSITION
COLLAR
“DISCONNECTED
VENT” WARNING
STICKER
FIGURE 21
Page 14
VENT PIPE
(min. 6” length)
“DISCONNECTED
VENT” WARNING
STICKER
FLUE
TRANSITION
COLLAR
Page 15
Common Venting Using Metal-Lined Masonry Chimney
SEALED
MAX. LENGTH
-- SEE NOTE 1
5 ft. (1.5 m)
minimum
VENT CONNECTOR
4 in. (102 mm)
minimum
OTHER
APPLIANCE
NOTE 1 - Refer to the provided venting tables for installations. Refer to the capacity requirements shown in the provided venting tables.
BELOW.
MIN. LENGTH -- AS
SHORT AS PRACTICAL
FURNACE
EXTERIOR
CHIMNEY WITH
METAL
LINER
PERMANENTLY
SEALED FIREPLACE
OPENING
FIGURE 22 DO NOT insulate the space between the liner and the chimney wall with puffed mica or any other loose gran ular insulating material.
IMPORTANT
SINGLE appliance venting of a fan‐assisted furnace into a tile‐lined masonry chimney (interior or outside wall) is PROHIBITED. The chimney must first be lined with either type B1 vent or an insulated single wall flexible vent lining system which has been sized ac cording to the provided venting tables and the vent pipe manufacturer's instructions.
A fan-assisted furnace may be commonly vented into an existing lined masonry chimney if the following conditions are met:
The chimney is currently serving at least one drafthood-
equipped appliance;
The vent connectors and chimney are sized according
to the provided venting tables. If type B1 double‐wall vent is used inside a chimney, no oth er appliance can be vented into the chimney. The outer wall of type B1 vent pipe must not be exposed to flue products. A type B1 vent or masonry chimney liner shall terminate above the roof surface with a listed cap or a listed roof as sembly according to the terms of their respective listings and the vent manufacturer's instructions.
When inspection reveals that an existing chimney is not safe for the intended purpose, it shall be rebuilt to conform to nationally recognized standards, lined or relined with suitable materials, or replaced with a gas vent or chimney suitable for venting ML180UHT series units. The chimney passageway must be checked periodically to ensure that it is clear and free of obstructions.
Do not install a manual damper, barometric draft regulator, or flue restrictor between the furnace and the chimney.
Never connect a Category I appliance to a chimney that is servicing a solid-fuel appliance. If a fireplace chimney flue is used to vent this appliance, the fireplace opening must be permanently sealed.
A type B or listed chimney lining system that passes through an unused masonry chimney flue is not considered to be exposed to the outdoors.
General Venting Requirements
Vent all ML180UHT furnaces according to these instruc tions:
1 - Vent diameter recommendations and maximum allow
able piping runs are found in the provided venting tables.
2 - In no case should the vent or vent connector diameter
be less than the diameter specified in the provided venting tables.
3 - The minimum vent capacity determined by the sizing
tables must be less than the low fire input rating and the maximum vent capacity must be greater than the high fire input rating.
4 - Single appliance vents - If the vertical vent or tile‐lined
chimney has a larger diameter or flow area than the vent connector, use the vertical vent diameter to de termine the minimum vent capacity and the vent
connector diameter to determine the maximum vent capacity. The flow area of the vertical vent, however,
shall not exceed 7 times the flow area of the listed ap pliance categorized vent area, drafthood outlet area or flue collar area unless designed according to approved engineering methods.
5 - Multiple appliance vents - The flow area of the largest
section of vertical vent or chimney shall not exceed 7 times the smallest listed appliance categorized vent area, drafthood outlet area or flue collar area unless designed according to approved engineering meth ods.
Page 15
Page 16
Common Venting Using Tile-Lined Interior Masonry Chimney and Combined Vent Connector
MINIMUM LENGTH = AS SHORT AS PRACTICAL. FOR MAXIMUM LENGTH SEE NOTE TO LEFT
NOTE- Refer to provided venting tables for installations.
OTHER
APPLIANCE
FIGURE 23
6 - The entire length of single wall metal vent connector
shall be readily accessible for inspection, cleaning, and replacement.
7 - Single appliance venting configurations with zero lat
eral lengths (table 4) are assumed to have no elbows in the vent system. For all other vent configurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45° elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10% (0.90 x maximum listed capacity).
8 - The common venting tables (5 and 6) were generated
using a maximum horizontal vent connector length of 1-1/2 feet (.46 m) for each inch (25 mm) of connector diameter as follows:
TABLE 3
Connector Diameter
inches (mm)
3 (76) 4-1/2 (1.37) 4 (102) 6 (1.83)
5 (127) 7-1/2 (2.29)
6 (152) 9 (2.74)
7 (178) 10-1/2 (3.20)
Maximum Horizontal
Connector Length feet (m)
9 - If the common vertical vent is offset, the maximum
common vent capacity listed in the common venting tables should be reduced by 20%, the equivalent of two 90° elbows (0.80 x maximum common vent capacity). The horizontal length of the offset shall not exceed
INTERIOR TILE-LINED MASONRY CHIMNEY
NOTE - the chimney must be properly sized per provided venting tables or lined with listed metal lining system.
VENT
CONNECTOR
FURNACE
PERMANENTLY SEALED FIREPLACE OPENING
1‐1/2 feet (.46 m) for each inch (25 mm) of common vent diameter.
10 - The vent pipe should be as short as possible with the
least number of elbows and angles required to com plete the job. Route the vent connector to the vent us ing the shortest possible route.
11 - A vent connector shall be supported without any dips
or sags and shall slope a minimum of 1/4 inch (6.4 mm) per linear foot (305 mm) of connector, back toward the appliance.
12 - Vent connectors shall be firmly attached to the furnace
flue collar by self-drilling screws or other approved means, except vent connectors of listed type B vent material which shall be assembled according to the manufacturer's instructions. Joints between sections of single wall connector piping shall be fastened by screws or other approved means.
13 - When the vent connector used for Category I ap
pliances must be located in or pass through a crawl space, attic or other areas which may be cold, that por tion of the vent connector shall be constructed of listed double‐wall type B vent material or material having equivalent insulation qualities.
14 - All venting pipe passing through floors, walls, and ceil
ings must be installed with the listed clearance to com bustible materials and be fire stopped according to lo cal codes. In absence of local codes, refer to NFGC (Z223.1).
15 - No portion of the venting system can extend into, or
pass through any circulation air duct or plenum.
Page 16
Page 17
16 - Vent connectors serving Category I appliances shall
not be connected to any portion of mechanical draft systems operating under positive pressure such as Category III or IV venting systems.
17 - If vent connectors are combined prior to entering the
common vent, the maximum common vent capacity listed in the common venting tables must be reduced by 10%, the equivalent of one 90° elbow (0.90 x maxi mum common vent capacity).
18 - The common vent diameter must always be at least as
large as the largest vent connector diameter.
19 - In no case, shall the vent connector be sized more than
two consecutive table size diameters over the size of the draft hood outlet or flue collar outlet.
20 - Do not install a manual damper, barometric draft regu
lator or flue restrictor between the furnace and the chimney.
21 - When connecting this appliance to an existing dedi
cated or common venting system, you must inspect the venting system's general condition and look for signs of corrosion. The existing vent pipe size must conform to these instructions and the provided venting tables. If the existing venting system does not meet these re quirements, it must be resized.
TABLE 4
Capacity of Type B Double-Wall Vents with Type B Double-Wall Connectors
Serving a Single Category I Appliance
Height
H
(feet)
6
8
10
15
20
30
Lateral
L
(feet)
0 0 78 0 152 0 251 0 375 2 13 51 18 97 27 157 32 232 4 21 49 30 94 39 153 50 227 6 25 46 36 91 47 149 59 223
0 0 84 0 165 0 276 0 415 2 12 57 16 109 25 178 28 263 5 23 53 32 103 42 171 53 255 8 28 49 39 98 51 164 64 247
0 0 88 0 175 0 295 0 447 2 12 61 17 118 23 194 26 289 5 23 57 32 113 41 187 52 280
10 30 51 41 104 54 176 67 267
0 0 94 0 191 0 327 0 502 2 11 69 15 136 20 226 22 339
5 22 65 30 130 39 219 49 330 10 29 59 40 121 51 206 64 315 15 35 53 48 112 61 195 76 301
0 0 97 0 202 0 349 0 540
2 10 75 14 149 18 250 20 377
5 21 71 29 143 38 242 47 367 10 28 64 38 133 50 229 62 351 15 34 58 46 124 59 217 73 337 20 48 52 55 116 69 206 84 322
0 0 100 0 213 0 374 0 587
2 9 81 13 166 14 283 18 432
5 21 77 28 160 36 275 45 421 10 27 70 37 150 48 262 59 405 15 33 64 44 141 57 249 70 389 20 56 58 53 132 66 237 80 374 30 NA NA 73 113 88 214 104 346
3 Inch 4 Inch 5 Inch 6 Inch
MIN MAX MIN MAX MIN MAX MIN MAX
NOTE - Single appliance venting configurations with zero lateral lengths are assumed to have no elbows in the vent system. For all other vent configurations, the vent system is assumed to have two 90° elbows. For each additional 90° elbow or equivalent (for example two 45° elbows equal one 90° elbow) beyond two, the maximum capacity listed in the venting table should be reduced by 10 percent (0.90 x maxi mum listed capacity).
Vent and Connector Diameter - D (inches)
Appliance Input Rating in Thousands of Btu Per Hour
Page 17
Page 18
Vent
Height
H
(feet)
6
8
10
15
20
30
TABLE 5
Vent Connector Capacity
Type B Double-Wall Vents with Type B Double-Wall Connectors
Serving Two or More Category I Appliances
Connector
Rise
R
(feet)
1 22 37 35 66 46 106 58 164 2 23 41 37 75 48 121 60 183 3 24 44 38 81 49 132 62 199
1 22 40 35 72 49 114 64 176 2 23 44 36 80 51 128 66 195 3 24 47 37 87 53 139 67 210
1 22 43 34 78 49 123 65 189 2 23 47 36 86 51 136 67 206 3 24 50 37 92 52 146 69 220
1 21 50 33 89 47 142 64 220 2 22 53 35 96 49 153 66 235 3 24 55 36 102 51 163 68 248
1 21 54 33 99 46 157 62 246 2 22 57 34 105 48 167 64 259 3 23 60 35 110 50 176 66 271
1 20 62 31 113 45 181 60 288 2 21 64 33 118 47 190 62 299 3 22 66 34 123 48 198 64 309
3 Inch 4 Inch 5 Inch 6 Inch
MIN MAX MIN MAX MIN MAX MIN MAX
Vent and Connector Diameter - D (inches)
Appliance Input Rating in Thousands of Btu Per Hour
TABLE 6
Common Vent Capacity
Type B Double-Wall Vents with Type B Double-Wall Connectors
Serving Two or More Category I Appliances
Vent
Height
H
(feet)
6 92 81 140 116 204 161 309 248
8 101 90 155 129 224 178 339 275
10 110 97 169 141 243 194 367 299
15 125 112 195 164 283 228 427 352
20 136 123 215 183 314 255 475 394
30 152 138 244 210 361 297 547 459
FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT FAN + FAN FAN + NAT
4 Inch 5 Inch 6 Inch 7 Inch
Appliance Input Rating in Thousands of Btu Per Hour
Common Vent Diameter - D (inches)
Page 18
Page 19
Removal of the Furnace from Common Vent
In the event that an existing furnace is removed from a venting system commonly run with separate gas ap pliances, the venting system is likely to be too large to prop erly vent the remaining attached appliances.
Conduct the following test while each appliance is operat ing and the other appliances (which are not operating) re main connected to the common venting system. If the vent ing system has been installed improperly, you must correct the system as indicated in the general venting re quirements section.
Using local codes, resize the common venting system to the minimum vent pipe size.
Gas Piping
See local codes for gas piping requirements and gas pipe sizing tables.
Gas supply piping should not allow more than 125 Pa (0.5”W.C.) drop in pressure between gas meter and unit. Supply gas pipe must not be smaller than unit gas connec tion.
WARNING
CARBON MONOXIDE POISONING HAZARD Failure to follow the steps outlined below for each
appliance connected to the venting system being placed into operation could result in carbon mon oxide poisoning or death. The following steps shall be followed for each ap pliance connected to the venting system being placed into operation, while all other appliances connected to the venting system are not in operation:
1 - Seal any unused openings in the common venting sys
tem.
2 - Inspect the venting system for proper size and horizon
tal pitch. Determine that there is no blockage, restric tion, leakage, corrosion, or other deficiencies which could cause an unsafe condition.
3 - Close all building doors and windows and all doors be
tween the space in which the appliances remaining connected to the common venting system are located and other spaces of the building. Turn on clothes dry ers and any appliances not connected to the common venting system. Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they will oper ate at maximum speed. Do not operate a summer ex haust fan. Close fireplace dampers.
4 - Follow the lighting instructions. Turn on the appliance
that is being inspected. Adjust the thermostat so that the appliance operates continuously.
5 - After the burner have operated for 5 minutes, test for
leaks of flue gases at the draft hood relief opening. Use the flame of a match or candle.
6 - After determining that each appliance connected to the
common venting system is venting properly, (step 3) return all doors, widows, exhaust fans, fireplace damp ers, and any other gas-burning appliances to their pre vious mode of operation.
7 - If a venting problem is found during any of the preced
ing tests, the common venting system must be modi fied to correct the problem.
CAUTION
If a flexible gas connector is required or allowed by the authority that has jurisdiction, black iron pipe shall be installed at the gas valve and extend outside the furnace cabinet. The flexible connector can then be added between the black iron pipe and the gas supply line.
Gas Supply
1 - This unit is shipped standard for left or right side instal
lation of gas piping (or top entry in horizontal applica tions). Connect the gas supply to the piping assembly.
2 - When connecting the gas supply piping, consider fac
tors such as length of run, number of fittings, and fur nace rating to avoid excessive pressure drop.
3 - The gas piping must not run in or through air ducts,
clothes chutes, gas vents or chimneys, dumb waiters, or elevator shafts.
4 - The piping should be sloped 6.4 mm (1/4 in) per 4.57 m
(15 ft.) upward toward the meter from the furnace. The piping must be supported at proper intervals every
2.44 to 3.01 m (8 to 10 ft) with suitable hangers or straps. Install a drip leg in vertical pipe runs to the unit.
5 - A 3 mm (1/8”) N.P.T. plugged tap or pressure post is
located on the gas valve to facilitate test gauge con nection. See figure 29.
6 - In some localities, codes may require the installation of
a manual main shut‐off valve and union (furnished by the installer) external to the unit. The union must be of the ground joint type.
IMPORTANT
Compounds used on threaded joints of gas piping must be resistant to the actions of liquified petro leum gases.
NOTE - If emergency shutoff is necessary, shut off the main manual gas valve and disconnect main power to the furnace. The installer should properly label these devices.
Page 19
Page 20
MANUAL
MAIN SHUT-OFF
VALVE
(With 1/8 in. NPT
Plugged Tap Shown)
GROUND
JOINT
UNION
Left Side Piping
(Standard)
AUTOMAT
IC
GAS VALVE
AUTOMATIC
GAS VALVE
MANUAL
MAIN SHUT-OFF
VALVE
(With 1/8 in. NPT
Plugged Tap
Shown)
GROUND
JOINT
UNION
DRIP LEG
MANUAL
MAIN SHUT-OFF
VALVE
GROUND
JOINT
UNION
DRIP LEG
DRIP LEG
FIELD
PROVIDED
AND INSTALLED
NOTE - BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET
FIGURE 24
MANUAL
MAIN SHUT-OFF
VALVE
GROUND
JOINT
UNION
DRIP LEG
Right Side Piping
(Alternate)
Horizontal Application
Left-Side Air Discharge
MAIN SHUT-OFF
MANUAL
VALVE
Horizontal Application
Right-Side Air Discharge
FIELD
PROVIDED
NOTE - BLACK IRON PIPE ONLY TO BE ROUTED INSIDE OF CABINET
AND INSTALLED
FIGURE 25
GROUND
JOINT
UNION
DRIP LEG
Page 20
Page 21
Leak Check
After gas piping is completed, carefully check all piping connections (factory- and field-installed) for gas leaks. Use a leak detecting solution or other preferred means.
NOTE - If emergency shutoff is necessary, shut off the main manual gas valve and disconnect the main power to the furnace. The installer should properly label these de vices.
CAUTION
Some soaps used for leak detection are corrosive to certain metals. Carefully rinse piping thoroughly af ter leak test has been completed. Do not use matches, candles, flame or other sources of ignition to check for gas leaks.
The furnace must be isolated by closing its individual manual shut‐off valve and disconnecting from from the gas supply system the during any pressure testing of the gas supply system at pressures greater than 1/2 psig (3.48 kPa, 14 inches w.c.).
IMPORTANT
When testing pressure of gas lines, gas valve must be disconnected and isolated. See figure 26. Gas valves can be damaged if subjected to pressures greater than 1/2 psig (3.48 kPa, 14 inches w.c.).
MANUAL MAIN
SHUT-OFF VALVE
WILL NOT HOLD
NORMAL TEST
PRESSURE
1/8 NPT PLUG
FIGURE 26
ISOLATE
GAS VALVE
FURNACE
CAP
Electrical
CAUTION
Electrostatic discharge can affect elec tronic components. Take precautions to neutralize electrostatic charge by touching your hand and tools to metal prior to handling the control.
Refer to figure 28 schematic wiring diagram.
1 - Ensure that power connection point is located with 2m
of furnace.
2 - Holes are on both sides of the furnace cabinet to facili
tate thermostat wiring.
3 - Before connecting the thermostat wiring, check to
make sure the wires will be long enough for servicing at a later date. Remove the blower access panel to check the length of the wire.
4 - Complete the wiring connections to the equipment.
Use the provided unit wiring diagram shown in figure
28. 18-gauge wire or larger that is suitable for Class II rating for thermostat connections.
5 - Electrically ground the unit according to local codes.
NOTE - The ML180UHT furnace contains electronic components that are polarity sensitive. Make sure that the furnace is wired correctly and is properly grounded.
6 - One line voltage “EAC” spade terminal is provided on
the furnace control board. Any electronic air cleaner rated up to one amp can be connected to this terminal with the neutral leg of the circuit being connected to one of the provided neutral terminals. See figure 27 for control board configuration. This terminal is energized when the indoor blower is operating.
7 - One line voltage “HUM” spade terminal is provided on
the furnace control board. Any humidifier rated up to one amp ca`n be connected to this terminal with the neutral leg of the circuit being connected to one of the provided neutral terminals. See figure 27 for control board configuration. This terminal is energized in the heating mode when the combustion air inducer is oper ating.
8 - Install the room thermostat according to the instruc
tions provided with the thermostat. See figure 28 for thermostat designations. If the furnace is being matched with a heat pump, refer to the instruction packaged with the dual fuel thermostat.
Indoor Blower Speeds
1 - When the thermostat is set to “FAN ON,” the indoor
blower will run continuously on the heating speed when there is no cooling or heating demand.
2 - When the ML180UHT is running in the heating mode,
the indoor blower will run on the heating speed.
3 - When there is a cooling demand, the indoor blower will
run on the cooling speed.
Generator Use - Voltage Requirements
The following requirements must be kept in mind when specifying a generator for use with this equipment:
The furnace requires 230 volts + The furnace operates at 50 Hz + The furnace integrated control requires both polarity
and proper ground. Both polarity and proper grounding should be checked before attempting to operate the furnace on either permanent or temporary power.
Generator should have a wave form distortion of less
than 5% THD (total harmonic distortion)
10%. 5% .
Page 21
Page 22
Integrated Control
INTEGRATED CONTROL
(Automatic Hot Surface Ignition System)
TERMINAL DESIGNATIONS
HUM - Humidifier 240VAC LINE - Input 240VAC XFMR - Transformer 240VAC EAC - Electronic Air Cleaner 240VAC COOL - Cool Speed 240VAC PARK1, PARK2 - Dead terminals for alternate speed taps NEUTRALS - Neutral terminals 240VAC HEAT - Heating Speed 240VAC FS - Flame Sense
FIGURE 27
Page 22
Page 23
ML180UHT Schematic Wiring Diagram
FIGURE 28
Page 23
Page 24
Unit Start-Up
FOR YOUR SAFETY READ BEFORE LIGHTING
WARNING
Do not use this furnace if any part has been underwa ter. A flood-damaged furnace is extremely danger ous. Attempts to use the furnace can result in fire or explosion. Immediately call a qualified service tech nician to inspect the furnace and to replace all gas controls, control system parts, and electrical parts that have been wet or to replace the furnace, if deemed necessary.
WARNING
If overheating occurs or if gas supply fails to shut off, shut off the manual gas valve to the appliance before shutting off electrical supply.
CAUTION
Before attempting to perform any service or mainte nance, turn the electrical power to unit OFF at dis connect switch.
BEFORE LIGHTING smell all around the appliance area
for gas. Be sure to smell next to the floor because some gas is heavier than air and will settle on the floor.
The gas valve on the ML180UHT unit will be equipped with a gas control switch. Use only your hand to move the switch. Never use tools. If the switch will not turn or if the control switch will not move by hand, do not try to repair it.
Placing the furnace into operation:
ML.180UHT units are equipped with an automatic ignition system. Do not attempt to manually light burners on these furnaces. Each time the thermostat calls for heat, the burn ers will automatically light. The ignitor does not get hot when there is no call for heat on units with an automatic ignition system.
WARNING
If you do not follow these instructions exactly, a fire or explosion may result causing property damage, personal injury or death.
Gas Valve Operation
1 - STOP! Read the safety information at the beginning of
this section.
2 - Set the thermostat to the lowest setting.
3 - Turn off all electrical power to the unit.
4 - This furnace is equipped with an ignition device which
automatically lights the burners. Do not try to light the burners by hand.
5 - Remove the upper access panel.
6 - Move lever on gas valve to OFF. See figure 29.
7 - Wait five minutes to clear out any gas. If you then smell
gas, STOP! Immediately call your gas supplier from a neighbor's phone. Follow the gas supplier's instruc tions. If you do not smell gas go to next step.
MANIFOLD
PRESSURE
OUTLET
PORT
INLET
PRESSURE
PORT
8 - Move lever on gas valve to ON. See figure 29.
9 - Replace the upper access panel.
10- Turn on all electrical power to to the unit.
11- Set the thermostat to desired setting.
NOTE - When unit is initially started, steps 1 through 11 may need to be repeated to purge air from gas line.
12- If the appliance will not operate, follow the instructions
“Turning Off Gas to Unit” and call your service techni cian or gas supplier.
Turning Off Gas to Unit
1 - Set the thermostat to the lowest setting.
2 - Turn off all electrical power to the unit if service is to be
performed.
3 - Remove the upper access panel.
White Rodgers 3600 Gas Valve
MANIFOLD
PRESSURE
ADJUSTMENT
SCREW
GAS VALVE SHOWN IN OFF POSITION
FIGURE 29
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4 - Move lever on gas valve to OFF. See figure 29. 5 - Replace the upper access panel.
Failure To Operate
If the unit fails to operate, check the following: 1 - Is the thermostat calling for heat? 2 - Are access panels securely in place? 3 - Is the main disconnect switch closed? 4 - Is there a blown fuse or tripped circuit breaker? 5 - Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off. 6 - Is gas turned on at the meter? 7 - Is the manual main shut‐off valve open? 8 - Is the internal manual shut‐off valve open? 9 - Is the unit ignition system in lock out? If the unit locks
out again, call the service technician to inspect the unit
for blockages. 10 - Is pressure switch closed? Obstructed flue will cause
unit to shut off at pressure switch. Check flue and outlet
for blockages. 11 - Are flame rollout switches tripped? If flame rollout
switches are tripped, call the service technician for in
spection.
Heating Sequence Of Operation (follow steps below or see Figure 28 for more detail)
1 - When thermostat calls for heat, combustion air blower
starts. 2 - Combustion air pressure switch proves blower opera
tion. Switch is factory-set and requires no adjustment. 3 - After a 15-second prepurge, the hot surface ignitor en
ergizes. 4 - After a 20-second ignitor warm-up period, the gas
valve solenoid opens. A 4-second trial for ignition peri
od begins. 5 - Gas is ignited, flame sensor proves the flame, and the
combustion process continues. 6 - If flame is not detected after first ignition trial, the igni
tion control will repeat steps 3 and 4 four more times
before locking out the gas valve (“WATCHGUARD”
flame failure mode). The ignition control will then auto
matically repeat steps 1 through 6 after 60 minutes. 7 - To interrupt the 60-minute “WATCHGUARD” period,
move thermostat from “Heat” to “OFF” then back to
“Heat.” Heating sequence then restarts at step 1.
Gas Pressure Adjustment
Gas Flow
To check for proper flow to combustion chamber, deter mine Btu input from appliance rating plate. Divide this input rating by the Btu per cubic foot of available gas. Result is the required number of cubic ft. per hour. Determine the flow of gas through the gas meter for two minutes and multi ply by 30 to get the hourly flow of gas.
IMPORTANT
The White Rodgers 36G24 gas valve (figure 29) is equipped with pressure posts for measuring supply and manifold pressures. The posts provide built-in
7.9mm (5/16”) hose connections and have an inte gral 2.4mm (3/32”) Allen-head screw. Rotate the screw counterclockwise one full turn to permit pres sure measurement. Reseat the screw (rotate one full turn clockwise) after measurements have been taken to prevent gas leakage.
Use pressure measurement kit 69M1701 to connect
7.9mm (5/16”) pressure post on gas valve to 6.4mm (1/4”) hose off the manometer.
Line Pressure Measurement
1 - Check the gas line pressure with the unit firing at maxi
mum rate. See table 8 for maximum and minimum line pressures.
After the line pressure has been checked and adjusted, check the manifold pressure per table 8. See figure 29 for the location of the manifold pressure adjustment screw.
Manifold Pressure Measurement
1 - Connect the outlet side of the gas to a manometer to
measure manifold pressure.
2 - Start unit and allow 5 minutes for unit to reach steady
state.
3 - While waiting for the unit to stabilize, observe the
flame. Flame should be stable and should not lift from burner. Natural gas should burn blue.
4 - After allowing unit to stabilize for 5 minutes, record
manifold pressure and compare to value given in table
8.
NOTE - Shut unit off and remove manometer as soon as an accurate reading has been obtained.
Proper Combustion
Furnace should operate a minimum 15 minutes with cor rect manifold pressure and gas flow rate before checking combustion. Take combustion sample beyond the flue out let and compare to the tables below. The maximum car
bon monoxide reading should not exceed 100 ppm.
TABLE 7
Unit
-070
-090
-110
-135
CO2%
For Nat
6.3 - 7.8 7.0 - 9.0
CO2%
For L.P.
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High Altitude
The manifold pressure may require adjustment and com bustion air pressure switch may need replacing to ensure proper combustion at higher altitudes. Refer to table 8 for manifold pressure and table 9 for pressure switch change and gas conversion kits.
TABLE 8
Manifold Pressure Settings at all Altitudes
IMPORTANT
For safety, shut unit off and remove manometer as soon as an accurate reading has been obtained. Take care to replace pressure tap plug.
Model
Input Size
All Models
Gas
Nat 0.87 0.72 0.67 0.62 0.87 1.12 3.20
LP/propane 2.49 2.27 2.19 2.12 2.49 2.74 3.20
0-610 m*
(0-2000 ft)
611-914 m*
(2001-3000 ft.)
915-1219 m*
(3001-4000 ft)
1220-1524 m*
(4001-5000 ft.)
1525-1981 m* (5001-6500 ft)
Line Pressure
kPa
Min Max
* See table 9 for proper high altitude gas conversion kit.
TABLE 9
Pressure Switch and Gas Conversion Kits at all Altitudes
High Altitude
Model
Input Size
070
090 80W51 80W56
110 80W51 80W56
135 No Change 80W51
NOTE - A natural to L.P. propane gas changeover kit is necessary to convert this unit. Refer to the changeover kit installation instruction for the conversion procedure.
High Altitude Pressure Switch Kit
0-610 m
(0-2000 ft)
No Change
611-1219 m
(2001-4000 ft)
80W51 80W56
1220-1981 m
(4001-6500 ft)
Other Unit Adjustments
Natural Gas Burner
Orifice Kit
1525-1981 m
(5001-6500 ft)
73W37 11K15 97W04 96W95
air temperatures have been allowed to stabilize, check the
Natural Gas to LP/Propane
Gas Change over Kit
0-1524 m
(0-5000 ft)
1525-1981 m
(5001-6500 ft)
LP/Propane to
Natural Gas
Change over Kit
1-1524 m
(1 5000 ft)
temperature rise. If necessary, adjust the blower speed to
Primary and Secondary Limits
The primary limit is located on the heating compartment vestibule panel. The secondary limits (if equipped) are lo cated in the blower compartment, attached to the back side of the blower. These auto reset limits are factory-set and require no adjustment.
Flame Rollout Switches
This manually reset switches are located on the top of the burner box.
Pressure Switch
The pressure switch is located in the heating compartment adjacent to the combustion air inducer. The switch checks for proper combustion air inducer operation before allow ing ignition trial. The switch is factory-set and requires no adjustment.
Temperature Rise
After the furnace has been started, and supply and return
maintain the temperature rise within the range shown on the unit nameplate. Increase the blower speed to decrease the temperature. Decrease the blower speed to increase the temperature rise. Failure to adjust the temperature rise may cause erratic limit operation.
Fan Control
The fan-on time of 30 seconds is not adjustable. The heat fan-off delay (amount of time that the blower operates after the heat demand has been satisfied) may be adjusted by changing the jumper position across the five pins on the in tegrated control. The unit is shipped with a factory fan-off delay setting of 60 seconds. The fan-off delay affects com fort and is adjustable to satisfy individual applications. Ad just the fan-off delay to achieve a supply air temperature between 32°C and 43°C at the moment that the blower is de-energized. Longer off delay settings provide lower re turn air temperatures; shorter settings provide higher re turn air temperatures. See figure 30.
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HEAT FAN‐OFF TIME IN SECONDS
Service
WARNING
NO JUMPER
To adjust fan-off timing, reposition jumper across pins to
60 Second
off Time
60
90
120
180
achieve desired setting.
90 Second
off Time
60
90
120
180
120 Second
off Time
60
90
120
180
180 Second
off Time
60
90
120
180
FIGURE 30
NOTE - Do not secure the electrical conduit directly to the air ducts or structure.
Electrical
1 - Check all wiring for loose connections. 2 - Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 230VAC +
10%.
3 - Check amp-draw on the blower motor with inner blow
er panel in place.
Unit Nameplate__________Actual__________
Blower Speeds
Follow the steps below to change the blower speeds. 1 - Turn off electrical power to furnace. 2 - Remove blower access panel. 3 - Disconnect existing speed tap at integrated control
speed terminal.
See unit Product Specifications bulletin for indoor blower data.
NOTE - Termination of any unused motor leads must be in sulated.
4 - Place unused blower speed tap on integrated control
“PARK” terminal or insulate.
5 - Refer to blower speed selection chart on unit wiring
diagram for desired heating or cooling speed. See Blower performance data beginning on the next page.
6 - Connect selected speed tap at integrated control
speed terminal. 7 - Resecure blower access panel. 8 - Turn on electrical power to furnace. 9 - Recheck temperature rise.
Electronic Ignition
The integrated control has an added feature of an internal Watchguard control. The feature serves as an automatic reset device for integrated control lockout caused by igni tion failure. This type of lockout is usually due to low gas line pressure. After one hour of continuous thermostat de mand for heat, the Watchguard will break and remake ther mostat demand to the furnace and automatically reset the integrated control to begin the ignition sequence.
ELECTRICAL SHOCK, FIRE,
OR EXPLOSION HAZARD.
Failure to follow safety warnings exactly could result in dangerous operation, serious injury, death or property damage. Improper servicing could result in dangerous opera tion, serious injury, death, or property damage. Before servicing, disconnect all electrical power to furnace. When servicing controls, label all wires prior to dis connecting. Take care to reconnect wires correctly. Verify proper operation after servicing.
At the beginning of each heating season, a qualified techni cian should check the system as follows:
Blower
Check the blower wheel for debris and clean if necessary. The blower motors are prelubricated for extended bearing life. No further lubrication is needed.
WARNING
The blower access panel must be securely in place when the blower and burners are operating. Gas fumes, which could contain carbon monoxide, can be drawn into living space resulting in personal inju ry or death.
Filters
All ML180UHT filters are installed external to the unit. Fil ters should be inspected monthly. Clean or replace the fil ters when necessary to ensure that the furnace operates properly. Replacement filters must be rated for high veloc ity airflow. Table 2 lists recommended filter sizes.
Flue And Chimney
1 - Check flue pipe, chimney and all connections for tight
ness and to make sure there is no blockage.
2 - Check unit for proper draft.
Electrical
1 - Check all wiring for loose connections. 2 - Check for the correct voltage at the furnace (furnace
operating). Correct voltage is 230VAC +
3 - Check amp-draw on the blower motor with inner blow
er panel in place. Unit Nameplate__________Actual__________
Cleaning the Burners
NOTE - Use papers or protective covering in front of the fur nace during cleaning.
1 - Turn off both electrical and gas power supplies to fur
nace.
2 - Label the wires from gas valve, rollout switches, prima
ry limit switch and make-up box then disconnect them.
10%.
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3 - Disconnect gas supply piping. Remove the screw se
curing the burner box cover and remove cover. Re move the four screws securing the burner manifold as sembly to the vestibule panel and remove the assembly from the unit.
4 - To clean burners, run a vacuum cleaner with a soft
brush attachment over the face of burners. Visually in spect inside the burners and crossovers for any block
ML180UHT BURNER ASSEMBLY & REMOVAL
age caused by foreign matter. Remove any blockage. Figure 31 shows burner detail.
5 - Reinstall burner box, manifold assembly and burner
box cover.
6 - Re-install gas supply and turn on electrical power to
furnace.
Retention Rings
Rollout Switches
Sensor
Ignitor
Cross Over
Manifold And Gas Valve
FIGURE 31
Repair Parts List
The following repair parts are available through independent Lennox dealers. When ordering parts, include the complete furnace model number listed on the CSA International nameplate -- Example: ML180UH070TP36A-01. All service must
be performed by a licensed professional installer (or equivalent), service agency, or gas supplier.
Cabinet Parts
Upper access panel Blower panel Top cap
Control Panel Parts
Transformer Integrated control Door interlock switch Circuit breaker
Blower Parts
Blower wheel Blower housing Motor Motor mounting frame Motor capacitor Blower housing cutoff plate
Heating Parts
Flame sensor Heat exchanger assembly Gas manifold Combustion air inducer Gas valve Main burner cluster Main burner orifices Pressure switch Ignitor Primary limit control Flame rollout switch (s) Secondary limit
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