Lennox MERIT ML193UH Installation Instructions Manual
INSTALLATION
E 2012 Lennox Industries Inc.
Dallas, Texas, USA
INSTRUCTIONS
ML193UH
®
MERIT
UPFLOW / HORIZONTAL AIR DISCHARGE
507010−01
08/2012
Supersedes 06/2012
SERIES GAS FURNACE
Litho U.S.A.
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.
CAUTION
AIR FLOW
AIR FLOW
HORIZONTAL LEFT
UPFLOW
AIR FLOW
HORIZONTAL RIGHT
Table of Contents
Unit Dimensions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
ML193UH Gas Furnace 3. . . . . . . . . . . . . . . . . . . . . . . . . .
Shipping and Packing List 3. . . . . . . . . . . . . . . . . . . . . . . .
Safety Information 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Use of Furnace as a Construction Heater 4. . . . . . . . . . .
General 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Combustion, Dilution, Ventilation Air 5. . . . . . . . . . . . . . . .
Setting Equipment 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filters 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Duct System 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Pipe and Fittings Specifications 13. . . . . . . . . . . . . . . . . . .
Joint Cementing Procedure 15. . . . . . . . . . . . . . . . . . . . . .
As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, personal injury or loss of life. Installation and service must
be performed by a licensed professional installer (or
equivalent), service agency or the gas supplier.
Venting Practices 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Vent Piping Guidelines 17. . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Piping 36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Electrical 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Integrated Control 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Unit Start Up 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Gas Pressure Measurement 43. . . . . . . . . . . . . . . . . . . . .
Proper Combustion 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
High Altitude 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Other Unit Adjustments 46. . . . . . . . . . . . . . . . . . . . . . . . . .
Twinning the ML193UH 47. . . . . . . . . . . . . . . . . . . . . . . . . .
Service 48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Repair Parts List 49. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Start Up Checklist 50. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
08/12
*2P0812*
Page 1
507010−01
*P507010-01*
ML193UH Unit Dimensions − inches (mm)
1
NOTE − 60C and 60D size units that require air
volumes 1800 cfm or over (850 L/s) must have
one of the following
1. Single side return air with transition, to accommodate
20 x 25 x 1 in. (508 x 635 x 25 mm) cleanable air
filter. Required to maintain proper air velocity.
2. Single side return air 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
2
Optional External Side Return Air Filter Kit is not for use
tables for additional information.
with the optional Return Air Base.
A
3/4
(19)
B
AIR FLOW
C
1
Bottom Return
Air Opening
9/16 (14)
2
OPTIONAL
SIDE RETURN
AIR FILTER KIT
(Either Side)
14−3/4
(375)
16
(406)
5/8
(16)
3/4
(19)
33
(838)
FRONT VIEW
ML193UH
Model No.
045XP24B
045XP36B
070XP24B
070XP36B
090XP36C
090XP48C
110XP48C
110XP60C
135XP60D
A B C D
in. mm in.
17−1/2 446 16−3/8 416 16 406 7−5/8
21 533 19−7/8 505 19−1/2 495 9−3/8 238
24−1/2 622 23−3/8 594 23 584 11−1/8 283
COMBUSTION
AIR INTAKE
SIDE RETURN
AIR FILTER KIT
1 (25)
Front Panel
6−9/16 (167)
9 (229)
12−5/8 (321)
(Either Side)
ELECTRICAL
INLET
(Either Side)
2 (51)
D
2
OPTIONAL
(Either Side)
Left
Right
3−1/4
(83)
mm
3−3/8
(86)
2−7/8
(73)
2 (51)
(Either Side)
GAS PIPING INLET
(Either Side)
6−1/2 (165)
(Either Side)
1
in. mm
EXHAUST AIR
OUTLET
SUPPLY AIR
OPENING
23−3/4
(603)
25
(635)
TOP VIEW
27−3/4
(705)
19−7/16
(494)
CONDENSATE
TRAP CONNECTION
(Either Side)
23
(584)
Side Return
Air Opening
(Either Side)
23−1/2
(597)
1
Bottom Return
Air Opening
SIDE VIEW
in.
9/16
(14)
1−1/2
(38)
14
(356)
1−15/16 (49)
mm
194
Page 2
ML193UH Gas Furnace
Shipping and Packing List
The ML193UH Category IV gas furnace is shipped ready
for installation in the upflow or horizontal position. The furnace is shipped with the bottom panel in place. The bottom panel must be removed if the unit is to be installed in
horizontal or upflow applications with bottom return air.
The ML193UH can be installed as either a Direct Vent or
a Non−Direct Vent gas central furnace.
The furnace is equipped for installation in natural gas applications. A conversion kit (ordered separately) is required for use in propane/LP gas applications.
NOTE − In Direct Vent installations, combustion air is taken
from outdoors and flue gases are discharged outdoors. In
Non−Direct Vent installations, combustion air is taken from
indoors or ventilated attic or crawlspace and flue gases are
discharged outdoors. See figures 1 and 2 for applications involving roof termination.
DIRECT VENT INSTALLATION NON−DIRECT VENT
EXHAUST OUTLET
COMBUSTION
AIR INTAKE OUTSIDE
OF HOUSE
INSTALLATION
EXHAUST
OUTLET
COMBUSTION
AIR INTAKE
INSIDE
OF HOUSE
Package 1 of 1 contains
1 − Assembled ML193UH unit
1 − Bag assembly containing the following:
1 − Snap bushing
1 − Snap plug
1 − Wire tie
1 − Condensate trap
1 − Condensate trap cap
1 − Condensate trap clamp
1 − 2" diameter debris screen
1 − 1/2" Threaded street elbow
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
The following items may also be ordered separately:
1 − Thermostat
1 − Propane/LP changeover kit
1 − Return air base kit
1 − Horizontal suspension kit
Safety Information
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage,
personal injury or loss of life. Installation and service
must be performed by a licensed professional installer (or equivalent), service agency or the gas supplier.
FIGURE 1
NON−DIRECT VENT
INSTALLATION
EXHAUST
OUTLET
COMBUSTION
AIR INTAKE INSIDE
VENTILATED
ATTIC SPACE
FIGURE 2
NON−DIRECT VENT
INSTALLATION
EXHAUST
OUTLET
COMBUSTION
AIR INTAKE INSIDE
VENTILATED
CRAWL SPACE
CAUTION
As with any mechanical equipment, personal injury
can result from contact with sharp sheet metal
edges. Be careful when you handle this equipment.
DANGER
Danger of explosion.
There are circumstances in which odorant used with
LP/propane gas can lose its scent. In case of a leak,
LP/propane gas will settle close to the floor and may
be difficult to smell. An LP/propane leak detector
should be installed in all LP applications.
Use only the type of gas approved for use with this furnace.
Refer to unit nameplate.
ML193UH units are CSA International certified to ANSI
Z21.47 and CSA 2.3 standards.
Building Codes
In the USA, installation of gas furnaces must conform with local building codes. In the absence of local codes, units must
be installed according to the current National Fuel Gas Code
(ANSI-Z223.1/NFPA 54). The National Fuel Gas Code is
Page 3
available from the following address:
American National Standards Institute, Inc.
11 West 42nd Street
New York, NY 10036
In Canada, installation must conform with current National
Standard of Canada CSA-B149 Natural Gas and Propane
Installation Codes, local plumbing or waste water codes
and other applicable local codes.
In order to ensure proper unit operation in non−direct vent
applications, combustion and ventilation air supply must be
provided according to the current National Fuel Gas Code
or CSA-B149 standard.
Installation Locations
This furnace is CSA International certified for installation
clearances to combustible material as listed on the unit
nameplate and in the table in figure 12. Accessibility and service clearances must take precedence over fire protection
clearances.
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 18 inches (457 mm) 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 atmosphere, the furnace must be installed according to recommended good practice requirements and current National Fuel Gas Code or CSA B149 standards.
NOTE − Furnace must be adjusted to obtain a temperature
rise within the range specified on the unit nameplate. Failure
to do so may cause erratic limit operation and premature heat
exchanger failure.
This ML193UH furnace must be installed so that its electrical components are protected from water.
Installed in Combination with a Cooling Coil
When this furnace is used with cooling coils (figure 3), it shall
be installed in parallel with, or on the upstream side of, cooling coils 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 manually 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. In addition, in the United States,
installation must conform with the current National Electric
Code, ANSI/NFPA No. 70. The National Electric Code
(ANSI/NFPA No. 70) is available from the following address:
National Fire Protection Association
1 Battery March Park
Quincy, MA 02269
In Canada, all electrical wiring and grounding for the unit
must be installed according to the current regulations of the
Canadian Electrical Code Part I (CSA Standard C22.1)
and/or local codes.
Heating Unit Installed Parallell to Air Handler Unit
(open during heating operation only)
(open during cooling operation only)
Dampers
Gas Unit
AIR FLOWAIR FLOW
Air Handler Unit
Dampers
Heating Unit Installed Upstream of Cooling Coil
AIR FLOW AIR FLOW
Cooling Coil
Gas Unit
FIGURE 3
NOTE − This furnace is designed for a minimum continuous return air temperature of 60°F (16°C) or an intermittent operation down to 55°F (13°C) dry bulb for cases
where a night setback thermostat is used. Return air temperature must not exceed 85°F (29°C) dry bulb.
The ML193UH furnace may be installed in alcoves, closets, attics, basements, garages, crawl spaces and utility
rooms in the upflow or horizontal position.
This furnace design has not been CSA certified for installa-
tion in mobile homes, recreational vehicles, or outdoors.
Use of Furnace as Construction Heater
Lennox does not recommend the use of ML193UH units as
a construction heater during any phase of construction.
Very low return air temperatures, harmful vapors and operation of the unit with clogged or misplaced filters will damage the unit.
ML193UH units may be used for heating of buildings or
structures under construction, if the following conditions
are met:
D The vent system must be permanently installed per
these installation instructions.
D A room thermostat must control the furnace. The use of
fixed jumpers that will provide continuous heating is not
allowed.
D The return air duct must be provided and sealed to the
furnace.
D Return air temperature range between 60°F (16°C) and
80°F (27°C) must be maintained.
D Air filters must be installed in the system and must be
maintained during construction.
Page 4
D Air filters must be replaced upon construction comple-
tion.
D The input rate and temperature rise must be set per the
furnace rating plate.
D One hundred percent (100%) outdoor air must be pro-
vided for combustion air requirements during construction. Temporary ducting may supply outdoor air to the
furnace. Do not connect duct directly to the furnace.
Size the temporary duct following these instructions in
section for Combustion, Dilution and Ventilation Air in a
confined space with air from outside.
D The furnace heat exchanger, components, duct system,
air filters and evaporator coils must be thoroughly
cleaned following final construction clean−up.
D All furnace operating conditions (including ignition, in-
put rate, temperature rise and venting) must be verified
according to these installation instructions.
• The A" coil drain pan is high quality engineering polymer with a maximum service temperature of 500° F.
However, adequate space must be provided between
the drain pan and the furnace heat exchanger. At least
2" space is required for sectionalized heat exchanger
and and 4" for drum−type or oil−fired furnace exchanger.
Closer spacing may damage the drain pan and cause
leaking.
General
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
In addition to the requirements outlined previously, the following general recommendations must be considered
when installing a ML193UH furnace:
• Place the furnace as close to the center of the air distribution system as possible. The furnace should also be
located close to the vent termination point.
• When the furnace is installed in non−direct vent applications, do not install the furnace where drafts might blow
directly into it. This could cause improper combustion
and unsafe operation.
• When the furnace is installed in non−direct vent applications, do not block the furnace combustion air opening
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 insulated space, keep insulation away from the furnace.
• When the furnace is installed in an unconditioned
space, consider provisions required to prevent freezing
of condensate drain system.
CAUTION
ML193UH unit should not be installed in areas normally subject to freezing temperatures.
WARNING
The State of California has determined that this product 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.
WARNING
Insufficient combustion air can cause headaches,
nausea, dizziness or asphyxiation. It will also cause
excess water in the heat exchanger resulting in rusting 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 combustion 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
Combustion, Dilution & Ventilation Air
If the ML193UH is installed as a Non−Direct Vent Furnace, follow the guidelines in this section.
NOTE − In Non−Direct Vent installations, combustion air
is taken from indoors or ventilated attic or crawlspace
and flue gases are discharged out−doors.
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
practices make it necessary to bring in air from outside
for combustion. 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 outside 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 furnace vent pipe or chimney. As a result,
combustion gases enter the living space creating a potentially dangerous situation.
In the absence of local codes concerning air for combus−
tion and ventilation, use the guidelines and procedures in
this section to install ML193UH furnaces to ensure efficient and safe operation. You must consider combustion
air needs and requirements for exhaust vents and gas
piping. A portion of this information has been reprinted
Page 5
with permission from the National Fuel Gas Code (ANSI−
Z223.1/NFPA 54). This reprinted material is not the complete and official position of the ANSI on the referenced
subject, which is represented only by the standard in its
entirety.
In Canada, refer to the CSA B149 installation codes.
CAUTION
Do not install the furnace in a corrosive or contaminated atmosphere. Meet all combustion and ventilation air requirements, as well as all local codes.
All gas-fired appliances require air for the combustion process. If sufficient combustion air is not available, the furnace or other appliance will operate inefficiently and unsafely. Enough air must be provided to meet the needs of all
fuel−burning appliances and appliances such as exhaust
fans which force air out of the house. When fireplaces, exhaust fans, or clothes dryers are used at the same time as
the furnace, much more air is required to ensure proper
combustion and to prevent a downdraft. Insufficient air
causes incomplete combustion which can result in carbon
monoxide.
In addition to providing combustion air, fresh outdoor air dilutes contaminants in the indoor air. These contaminants
may include bleaches, adhesives, detergents, solvents
and other contaminants which can corrode furnace components.
The requirements for providing air for combustion and ventilation depend largely on whether the furnace is installed in
an unconfined or a confined space.
Unconfined Space
Confined Space
A confined space is an area with a volume less than 50 cubic
feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the com−
bined 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 containing 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 either from inside the building or from outside.
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
spaces. Each opening must have a minimum free area of 1
square inch (645 mm2) per 1,000 Btu (.29 kW) per hour of
total input rating of all gas−fired equipment in the confined
space. Each opening must be at least 100 square inches
(64516 mm2). One opening shall be within 12 inches (305
mm) of the top of the enclosure and one opening within 12
inches (305 mm) of the bottom. See figure 4.
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM INSIDE
ROOF TERMINATED
EXHAUST PIPE
An unconfined space is an area such as a basement or
large equipment room with a volume greater than 50 cubic
feet (1.42 m3) per 1,000 Btu (.29 kW) per hour of the combined 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 unconfined, 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.
OPENINGS
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
NOTE − Each opening shall have a free area of at least one square inch
per 1,000 Btu (645mm
all equipment in the enclosure, but not less than 100 square inches
(64516mm.
2).
ML193UH
2
per .29kW) per hour of the total input rating of
(To Adjacent
Unconfined
Space)
FIGURE 4
Page 6
Air from Outside
If air from outside is brought in for combustion and ventilation, the confined space shall be provided with two permanent openings. One opening shall be within 12" (305mm)
of the top of the enclosure and one within 12" (305mm) 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 indirectly
through vertical ducts. Each opening shall have a minimum free area of 1 square inch per 4,000 Btu (645mm
per 1.17kW) per hour of total input rating of all equipment
in the enclosure. When communicating with the outdoors
through horizontal ducts, each opening shall have a minimum free area of 1 square inch per 2,000 Btu (645mm
per .59kW) per total input rating of all equipment in the enclosure (See figure 5). It is also permissible to bring in air
for combustion from a ventilated attic (figure 6) or ventilated crawl space (figure 7).
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM OUTSIDE
(Inlet Air from Crawl Space and Outlet Air to Ouside)
VENTILATION LOUVERS
OUTLET
AIR
(Each end of attic)
ROOF TERMINATED
EXHAUST PIPE
(Inlet Air from Ventilated Crawlspace and Outlet Air to Outside)
Roof Terminated
Exhaust Pipe
2
Ventilation
2
Louvers
(Crawl space)
(Field Provided)
EQUIPMENT IN CONFINED SPACE
Furnace
Coupling or
3 in. to 2 in.
Transition
12 in.(305mm)
*Intake Debris Screen Provided)
Inlet Air
(Minimum
Above crawl
space floor)
* See table 6 for maximum vent lengths
NOTE−The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm
hour of the total input rating of all equipment in the enclosure.
2
per 1.17kW) per
FIGURE 7
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
NOTE−The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm
hour of the total input rating of all equipment in the enclosure.
FURNACE
INLET
AIR
VENTILATION
LOUVERS
(For unheated
crawl space)
2
per 1.17kW) per
FIGURE 5
(Inlet Air from Ventilated Attic and Outlet Air to Outside)
Roof Terminated
Exhaust Pipe
EQUIPMENT IN CONFINED SPACE
Ventilation Louvers
Inlet Air
(Minimum
12 in.(305mm) Above
attic floor)
*Intake Debris
Screen
(Provided)
Furnace
* See table 6 for maximum vent lengths
NOTE−The inlet and outlet air openings shall each have a free area
of at least one square inch per 4,000 Btu (645mm
hour of the total input rating of all equipment in the enclosure.
2
per 1.17kW) per
FIGURE 6
If air from outside is brought in for combustion and ventilation, the confined space must have two permanent openings. One opening shall be within 12 inches (305 mm) of
the top of the enclosure and one opening within 12 inches
(305 mm) 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 indirectly through vertical ducts. Each opening shall have a
minimum free area of 1 square inch (645 mm2) per 4,000
Btu (1.17 kW) per hour of total input rating of all equipment
in the enclosure. See figures 5 and 8. When communicating with the outdoors through horizontal ducts, each opening shall have a minimum free area of 1 square inch (645
mm2) per 2,000 Btu (.56 kW) per total input rating of all
equipment in the enclosure. See figure 9.
When ducts are used, they shall be of the same cross−sectional area as the free area of the openings to which they
connect. The minimum dimension of rectangular air ducts
shall be no less than 3 inches (75 mm). In calculating free
area, the blocking effect of louvers, grilles, or screens
must be considered. If the design and free area of protective covering is not known for calculating the size opening
required, it may be assumed that wood louvers will have
20 to 25 percent 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 operation.
Page 7
EQUIPMENT IN CONFINED SPACE − ALL AIR FROM OUTSIDE
ROOF TERMINATED
EXHAUST PIPE
(All Air Through Ventilated Attic)
VENTILATION LOUVERS
(Each end of attic)
OUTLET
AIR
leg). See figure 10. The bolt and washer must be re-
moved before the furnace is placed into operation. After the bolt and washer have been removed, the rigid leg
will not touch the blower housing.
ML193UH090P48C
and ML193UH110P48C
with 1/2 HP Blower Motor
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
NOTE−The inlet and outlet air openings shall each have a free area of
at least one square inch per 4,000 Btu (645mm
of the total input rating of all equipment in the enclosure.
FURNACE
INLET AIR
(Ends 12" above
bottom)
2
per 1.17kW) per hour
FIGURE 8
EQUIPMENT IN CONFINED SPACE −
ALL AIR FROM OUTSIDE
ROOF TERMINATED
EXHAUST PIPE
OUTLET AIR
SIDE WALL
TERMINATED
EXHAUST PIPE
(ALTERNATE
LOCATION)
NOTE−Each air duct opening shall have a free area of at least one
square inch per 2,000 Btu (645mm
input rating of all equipment in the enclosure. If the equipment room
is located against an outside wall and the air openings communicate directly with the outdoors, each opening shall have a free area
of at least 1 square inch per 4,000 Btu (645mm
hour of the total input rating of all other equipment in the enclosure.
FURNACE
INLET AIR
2
per .59kW) per hour of the total
2
per 1.17kW) per
FIGURE 9
Shipping Bolt Removal
Units with 1/2 hp blower motor are equipped with three flexible legs and one rigid leg. 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
RIGID LEG
(Remove shipping bolt
and washer)
FIGURE 10
Installation − Setting Equipment
WARNING
Do not connect the return air duct to the back of the
furnace. Doing so will adversely affect the operation
of the safety control devices, which could result in
personal injury or death.
WARNING
Blower access panel must be securely in place when
blower and burners are operating. Gas fumes, which
could contain carbon monoxide, can be drawn into
living space resulting in personal injury or death.
Upflow Applications
The ML193UH gas furnace can be installed as shipped
in the upflow position. Refer to figure 12 for clearances.
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,
condensate trap and drain connections, and installation
and service clearances [24 inches (610 mm) at unit
front]. The unit must be level from side to side. Unit may
be positioned from level to 1/2" toward the front to aid in
draining. See figure 11.
Allow for clearances to combustible materials as indicated
on the unit nameplate.
Page 8
SETTING EQUIPMENT
UPFLOW APPLICATION
UNIT
FRONT
SIDE VIEW
AIR FLOW
FRONT VIEW
UNIT
FRONT
AIR FLOW
SIDE VIEW
1/2"
max.
HORIZONTAL APPLICATION
UNIT
FRONT
FRONT VIEW
AIR FLOW
END VIEW
1/2"
max.
Unit must be level side−to−side. Unit may be positioned from level to 1/2" toward the front to aid in draining.
FIGURE 11
Page 9
WARNING
Improper installation of the furnace can result in personal injury or death. Combustion and flue products
must never be allowed to enter the return air system
or air in the living space. Use sheet metal screws and
joint tape to seal return air system to furnace.
In platform installations with furnace return, the furnace should be sealed airtight to the return air plenum. 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. Allow absolutely no sagging, cracks, gaps, etc.
For no reason should return and supply air duct systems ever be connected to or from other heating devices such as a fireplace or stove, etc. Fire, explosion, carbon monoxide poisoning, personal injury
and/or property damage could result.
Installation Clearances
Top
Left Side
Right Side
Return Air Guidelines
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.
Refer to Engineering Handbook for additional information.
ML193UH applications which include side return air
and a condensate trap installed on the same side of the
cabinet (trap can be installed remotely within 5 ft.) require either a return air base or field−fabricated transition to accommodate an optional IAQ accessory taller
than 14.5". See figure 13.
Side Return Air
(with transition and filter)
Bottom (Floor)
Top/Plenum 1 in. (25 mm)
*Front 0
Back 0
Sides 0†
Vent 0
Floor 0‡
*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
†Allow proper clearances to accommodate condensate trap.
‡For installations on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.
FIGURE 12
1−1/2”
Transition
FIGURE 13
20” X 25” X 1”
(508mmX635mmX 25mm)
Air Filter
Return
Air
Plenum
Page 10
CONDENSATE
TRAP
Optional Return Air Base
(Upflow Applications Only)
FURNACE
FRONT
1
23 (584)
Overall
(Maximum)
1
Unit side return air
Opening
5−5/8
(143)
SIDE RETURN
AIR OPENINGS
(Either Side)
26−7/8
(683)
SIDE VIEW
23
(584)
1
Minimum
11 (279)
2
Maximum
14 (356)
1
22−7/16
(570)
Overall
(Maximum)
3/4
(19)
AIR FLOW
17−1/2 (446) B Width (50W98)
21 (533) C Width (50W99)
24−1/2 (622) D Width (51W00)
INDOOR AIR
QUALITY
CABINET
(PCO, Filter
Cabinet, etc.)
OPTIONAL
RETURN
AIR BASE
IF BASE
IS USED
WITHOUT
IAQ CABINET,
A SINGLE
RETURN AIR
PLENUM
MUST
COVER BOTH
UNIT AND
RETURN
AIR BASE
OPENINGS
3−1/4
(83)
7−1/4
(184)
FRONT VIEW
NOTE− Optional side return air filter kits are not for use with 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.
Minimum unit side return air opening dimensions for units requiring 1800 cfm of air and over (W x H): 23 x 11 in. (584 x 279 mm).
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 14 inches) is preferred.
FIGURE 14
Removing the Bottom Panel
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 15.
Horizontal Applications
Screw
Bottom Panel
FIGURE 15
Bottom Cap
Page 11
WARNING
Do not install the furnace on its front or back.
See figure 16.
Front
FIGURE 16
Back
The ML193UH furnace can be installed in horizontal applications with either right− or left−hand air discharge.
Refer to figure 17 for clearances in horizontal applications.
Horizontal Application
Installation Clearances
Right−Hand Discharge
NOTE − Heavy−gauge 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 installation.
Cooling coils and supply and return air plenums must
be supported separately.
Left End Right End
Air
Flow
Bottom (Floor)**
Left−Hand Discharge
Top
Left End Right End
Air
Flow
Bottom (Floor)**
Top 0
Front* 0
Back 0
Ends 0
Vent 0
Floor 0‡
*Front clearance in alcove installation must be 24 in. (610 mm).
Maintain a minimum of 24 in. (610 mm) for front service access.
**An 8" service clearance must be maintained below the unit to
provide for servicing of the condensate trap.
‡For installations on a combustible floor, do not install the furnace
directly on carpeting, tile or other combustible materials other
than wood flooring.
Air
Flow
Air
Flow
FIGURE 17
Suspended Installation of Horizontal Unit
This furnace may be installed in either an attic or a crawlspace. Either suspend the furnace from roof rafters or
floor joists, as shown in figure 18, or install the furnace on a
platform, as shown in figure 19. A horizontal suspension
kit (51W10) may be ordered from Lennox or use equivalent.
HORIZONTAL SUSPENSION KIT
Metal Strap
(typical)
Internal Brace
(provided with kit)
Bracket
(typical)
Air
Flow
FIGURE 18
NOTE − When the furnace is installed on a platform or with
the horizontal suspension kit in a crawlspace, it must be
elevated enough to avoid water damage, accommodate
drain trap and to allow the evaporator coil to drain.
Platform Installation of Horizontal Unit
1 − Select location for unit keeping in mind service and
other necessary clearances. See figure 17.
2 − Construct a raised wooden frame and cover frame
with a plywood sheet. If unit is installed above finished
space, fabricate an auxiliary drain pan to be installed
under unit. Set unit in drain pan as shown in figure 19.
Leave 8 inches for service clearance below unit for
condensate trap.
3 − Provide a service platform in front of unit. When instal-
ling the unit in a crawl space, a proper support platform
may be created using cement blocks.
4 − Route auxiliary drain line so that water draining from
this outlet will be easily noticed by the homeowner.
Page 12
5 − If necessary, run the condensate line into a conden-
sate pump to meet drain line slope requirements. The
pump must be rated for use with condensing furnaces.
Protect the condensate discharge line from the pump
to the outside to avoid freezing.
6 − Continue with exhaust, condensate and intake piping
installation according to instructions.
INTAKE PIPE
EXHAUST PIPE
SERVICE PLATFORM
*GAS CONNECTION
RAISED
PLATFORM
FIGURE 19
Return Air −− Horizontal Applications
Return air may be brought in only through the end of a furnace installed in the horizontal position. The furnace is
equipped with a removable bottom panel to facilitate
installation. See figure 15.
Filters
This unit is not equipped with a filter or rack. A field−provided high velocity rated filter is required for the unit to operate properly. Table 1 lists recommended filter sizes.
A filter must be in place whenever the unit is operating.
TABLE 1
Furnace
Cabinet Width
17−1/2" 16 X 25 X 1 (1) 16 X 25 X 1 (1)
21" 16 X 25 X 1 (1) 20 X 25 X 1 (1)
24−1/2" 16 X 25 X 1 (2) 24 X 25 X 1 (1)
Side Return Bottom Return
Filter Size
Duct System
Use industry-approved standards to size and install the
supply and return air duct system. Refer to ACCA Manual
D. This will result in a quiet and low-static system that has
uniform air distribution.
NOTE − This furnace is not certified for operation in heating
mode (indoor blower operating at selected heating speed)
with an external static pressure which exceeds 0.5 inches
w.c. Operation at these conditions may result in improper
limit operation.
Supply Air Plenum
If the furnace is installed without a cooling coil, a removable
access panel should be installed in the supply air duct. The
access panel should be large enough to permit inspection
of the heat exchanger. The furnace access panel must always be in place when the furnace is operating and it must
not allow leaks.
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 device (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
reverse flow of the flue gas may result in incomplete combustion and the formation of carbon monoxide gas. This
raw gas or toxic fumes might then be distributed throughout the house by the furnace duct system.
Return air can be brought in through the bottom or either
side of the furnace (return air brought into either side furnace allowed in upflow applications only). If a furnace with
bottom return air is installed on a platform, make an airtight
seal between the bottom of the furnace and the platform to
ensure that the unit operates properly and safely. Use fiberglass sealing strips, caulking, or equivalent sealing 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.
Pipe & Fittings Specifications
All pipe, fittings, primer and solvent cement must conform
with American National Standard Institute and the American Society for Testing and Materials (ANSI/ASTM) standards. The solvent shall be free flowing and contain no
lumps, undissolved particles or any foreign matter that adversely affects the joint strength or chemical resistance of
the cement. The cement shall show no gelation, stratification, or separation that cannot be removed by stirring. Refer to the table 2 below for approved piping and fitting materials.
CAUTION
Solvent cements for plastic pipe are flammable liquids and should be kept away from all sources of
ignition. Do not use excessive amounts of solvent
cement when making joints. Good ventilation should
be maintained to reduce fire hazard and to minimize
breathing of solvent vapors. Avoid contact of cement
with skin and eyes.
Page 13
PIPING AND FITTINGS SPECIFICATIONS
TABLE 2
Schedule 40 PVC (Pipe) D1785
Schedule 40 PVC (Cellular Core Pipe) F891
Schedule 40 PVC (Fittings) D2466
Schedule 40 CPVC (Pipe) F441
Schedule 40 CPVC (Fittings) F438
SDR−21 PVC or SDR−26 PVC (Pipe) D2241
SDR−21 CPVC or SDR−26 CPVC (Pipe) F442
Schedule 40 ABS Cellular Core DWV (Pipe) F628
Schedule 40 ABS (Pipe) D1527
Schedule 40 ABS (Fittings) D2468
ABS−DWV (Drain Waste & Vent)
(Pipe & Fittings)
PVC−DWV (Drain Waste & Vent)
Pipe & Fittings)
PRIMER & SOLVENT CEMENT
PVC & CPVC Primer F656
PVC Solvent Cement D2564
CPVC Solvent Cement F493
ABS Solvent Cement D2235
PVC/CPVC/ABS All Purpose Cement For
Fittings & Pipe of the same material
ABS to PVC or CPVC Transition Solvent
Cement
CANADA PIPE & FITTING & SOLVENT
CEMENT
PVC & CPVC Pipe and Fittings
PVC & CPVC Solvent Cement
ABS to PVC or CPVC Transition Cement
D2661
D2665
ASTM
SPECIFICATION
D2564, D2235, F493
D3138
MARKING
ULCS636
IMPORTANT
ML193UH exhaust and intake connections are made
of PVC. Use PVC primer and solvent cement when
using PVC vent pipe. When using ABS vent pipe, use
transitional solvent cement to make connections to
the PVC fittings in the unit.
Use PVC primer and solvent cement or ABS solvent cement
meeting ASTM specifications, refer to Table 2. As an alternate, use all purpose cement, to bond ABS, PVC, or CPVC
pipe when using fittings and pipe made of the same materials. Use transition solvent cement when bonding ABS to either PVC or CPVC.
Low temperature solvent cement is recommended during
cooler weather. Metal or plastic strapping may be used for
vent pipe hangers. Uniformly apply a liberal coat of PVC
primer for PVC or use a clean dry cloth for ABS to clean inside socket surface of fitting and male end of pipe to depth
of fitting socket.
Canadian Applications Only − Pipe, fittings, primer
and solvent cement used to vent (exhaust) this appliance must be certified to ULC S636 and supplied by a
single manufacturer as part of an approved vent (exhaust) system. In addition, the first three feet of vent
pipe from the furnace flue collar must be accessible for
inspection.
Page 14
Vent
Input Size
Pipe
Dia. in.
2
045
2−1/2
3
2
070
2−1/2
3
2
090
2−1/2
3
2 YES YES YES
110
2−1/2 YES YES
3 YES YES
135 3 YES
OUTDOOR TERMINATION USAGE
TABLE 3
STANDARD CONCENTRIC
FlushMount
Kit
51W11
3
YES YES
3
YES YES
3
YES YES
3
YES YES
3
YES YES
3
YES YES
3
YES YES YES
3
YES YES YES
3
YES YES YES
2 inch 3 inch 2 inch
22G44 (US)
4
30G28 (CA)
Wall Kit Wall Ring Kit
44J40
(US)
4
81J20 (CA)
1
YES
1
YES
1
YES
1
YES
1
YES
1
YES
YES
15F74
1
YES
1
YES
1
YES
1
YES
1
YES
1
YES
1−1/2 inch 2 inch 3 inch
Field
Fabricated
5
YES
5
YES
5
YES
5
YES
5
YES
5
YES
5
YES YES YES
5
YES YES YES
5
YES YES YES
5
YES YES YES
5
YES YES YES
5
YES YES YES
5
YES YES
71M80
(US)
4
44W92
(CA)
2
YES
2
YES
2
YES
2
YES
2
YES
2
YES
69M29
(US)
4
44W92
(CA)
60L46 (US)
4
44W93 (CA)
NOTE − Standard Terminations do not include any vent pipe or elbows external to the structure. Any vent pipe or elbows external to the structure must be included in total vent length
calculations. See vent length tables.
1
Requires field−provided outdoor 1−1/2" exhaust accelerator.
2
Concentric kits 71M80 and 44W92 include 1−1/2" outdoor accelerator, when uses with 045 and 070 input models.
3
Flush mount kit 51W11 includes 1−1/2 in. outdoor exhaust accelerator, required when used with 045, 070 and 090 input models.
4
Termination kits 30G28, 44W92, 4493 and 81J20 are certified to ULC S636 for use in Canada only.
5
See table 8 for vent accelerator requirements.
4 − Test fit joint and mark depth of fitting on outside of pipe.
Joint Cementing Procedure
All cementing of joints should be done according to the
specifications outlined in ASTM D 2855.
NOTE − A sheet metal screw may be used to secure the
intake pipe to the connector, if desired. Use a drill or self
tapping screw to make a pilot hole.
5 − Uniformly apply a liberal coat of PVC primer for PVC or
use a clean dry cloth for ABS to clean inside socket
surface of fitting and male end of pipe to depth of fitting
socket.
NOTE − Time is critical at this stage. Do not allow primer to dry before applying cement.
6 − Promptly apply solvent cement to end of pipe and in-
side socket surface of fitting. Cement should be ap-
DANGER
DANGER OF EXPLOSION!
Fumes from PVC glue may ignite during system
check. Allow fumes to dissipate for at least 5 minutes
before placing unit into operation.
plied lightly but uniformly to inside of socket. Take
care to keep excess cement out of socket. Apply second coat to end of pipe.
7 − Immediately after applying last coat of cement to pipe,
and while both inside socket surface and end of pipe
are wet with cement, forcefully insert end of pipe into
socket until it bottoms out. Turn PVC pipe 1/4 turn dur-
1 − Measure and cut vent pipe to desired length.
2 − Debur and chamfer end of pipe, removing any ridges
or rough edges. If end is not chamfered, edge of pipe
may remove cement from fitting socket and result in a
leaking joint.
3 − Clean and dry surfaces to be joined.
ing assembly (but not after pipe is fully inserted) to distribute cement evenly. DO NOT turn ABS or cellular
core pipe.
NOTE − Assembly should be completed within 20 seconds after last application of cement. Hammer blows
should not be used when inserting pipe.
Page 15
8 − After assembly, wipe excess cement from pipe at end
of fitting socket. A properly made joint will show a
bead around its entire perimeter. Any gaps may indicate an improper assembly due to insufficient solvent.
9 − Handle joints carefully until completely set.
CHIMNEY
OR GAS
VENT
(Check sizing
for water
heater only)
REPLACING FURNACE THAT
WAS PART OF A COMMON
VENT SYSTEM
Venting Practices
Piping Suspension Guidelines
SCHEDULE 40
PVC − 5’
all other pipe* − 3’
* See table 2 for allowable pipe.
NOTE − Isolate piping at the point where it exits the outside wall or
roof in order to prevent transmission of vibration to the structure.
Wall Thickness Guidelines
24" maximum
3/4" minimum
inside outside
Wall
FURNACE
(Replaced
by ML193)
WATER
HEATER
OPENINGS
(To Adjacent
Room)
If an ML193UH furnace replaces a furnace which
was commonly vented with another gas appliance,
the size of the existing vent pipe for that gas appliance must be checked. Without the heat of the
original furnace flue products, the existing vent pipe
is probably oversized for the single water heater or
other appliance. The vent should be checked for
proper draw with the remaining appliance.
FIGURE 21
Exhaust Piping (Figures 24 and 25)
Route piping to outside of structure. Continue with installation following instructions given in piping termination section.
insulation
(if required)
FIGURE 20
1 − In areas where piping penetrates joists or interior
walls, hole must be large enough to allow clearance on
all sides of pipe through center of hole using a hanger.
2 − When furnace is installed in a residence where unit is
shut down for an extended period of time, such as a
vacation home, make provisions for draining condensate collection trap and lines.
CAUTION
Do not discharge exhaust into an existing stack or
stack that also serves another gas appliance. If vertical discharge through an existing unused stack is required, insert PVC pipe inside the stack until the end
is even with the top or outlet end of the metal stack.
CAUTION
The exhaust vent pipe operates under positive pressure and must be completely sealed to prevent leakage of combustion products into the living space.
Page 16
Loading...