GAS FURNACES
HIGH EFFICIENCY - SINGLE STAGE CONDENSING FURNACES
92.1% AFUE
USER’S MANUAL
WARNING
FIRE OR EXPLOSION HAZARD
• Failure to follow safety warnings exactly could result in serious injury or property damage.
• Installation and service must be performed by a qualified installer, service agency or the gas
supplier.
• Do not store or use gasoline or other flammable vapors and liquids in the vicinity of this or any
other appliance.
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any phone in your building.
• Leave the building immediately.
• Immediately call your gas supplier from a neighbors phone. Follow the gas suppliers instructions.
• If you cannot reach your gas supplier, call the fire department.
DO NOT DESTROY. PLEASE READ CAREFULLY & KEEP IN A SAFE PLACE FOR FUTURE REFERENCE.
IMPORTANT! Please read all information in this manual thoroughly and become familiar with the capabilities and use of your
appliance before attempting to operate or maintain this unit. Pay attention to all safety warnings and any other special notes
highlighted in the manual. Safety markings are used frequently throughout this manual to designate a degree or level of seriousness
and should not be ignored.
Keep this literature where you have easy access to it in the future. If a problem occurs, check the instructions and follow
recommendations given. If these suggestions don’t eliminate your problem, call your servicing contractor. Under no circumstances
should the appliance owner attempt to install and/or service this equipment.
Some local codes require licensed installation / service personnel for this type of equipment. Improper service, adjustment, or
maintenance may cause explosion, fire, electrical shock or other hazardous conditions which may result in personal injury or
property damage.
M4RC Upflow Models
M4RL Downflow Models
2
IMPORTANT SAFETY INFORMATION .......................3
GAS SUPPLY & PIPING ..........................................3
VENTING SYSTEM .................................................. 3
FILTER .....................................................................4
CLEARANCES TO COMBUSTIBLES ......................4
SOURCES OF CORROSION ...................................4
FLOOD DAMAGE .....................................................4
ABOUT THE FURNACE ..............................................5
INTRODUCTION ......................................................5
CATEGORY IV (CONDENSING) FURNACES .......5
FILTER .....................................................................5
FURNACE LOCATION ............................................. 5
TROUBLESHOOTING .................................................5
COMPONENT LOCATIONS ........................................6
STARTUP & SHUTDOWN ...........................................7
STARTING THE FURNACE ..................................... 7
SHUTTING DOWN THE FURNACE ........................7
MAINTENANCE & INSPECTION ................................7
FURNACE & AIR DUCTS ........................................7
VENTING SYSTEM .................................................. 7
BLOWER & FILTER .................................................7
BURNER OPERATION ............................................7
NEW CONSTRUCTION ...........................................7
3
WARNING:
The furnace was shipped from the factory equipped
to operate on natural gas. Conversion to LP/propane
gas must be performed by a licensed HVAC technician
using a factory supplied conversion kit. Failure to use
the proper conversion kit can cause fire, explosion,
property damage, carbon monoxide poisoning,
personal injury, or death.
WARNING:
All gas piping and shutoff valves must be installed in
compliance with local codes and utility regulations
by licensed installers. DO NOT attempt to modify, or
tap into existing gas lines yourself. Fire or explosion
may result causing property damage, personal injury
or loss of life. Failure to follow the safety warnings
exactly could result in serious injury, death or property
damage.
VENTING SYSTEM
WARNING:
CARBON-MONOXIDE POISONING HAZARD
Failure to folow instructions could result in severe
personal injury or death due to carbon-monoxide
poisoning if combustion products infiltrate into
the building.
Check that all oepnings in the outsdie wall around
the vent (and air intake) pipe(s) are sealed to prefent
infiltration of combustion products into the building.
Check that furnace vent (and air intake) terminal(s)
are not obstructed in any way during all seasons.
AVERTISSEMENT :
RISQUE D’INTOXICATION AU MONOXYDE
DE CARBONE
Si ces directives ne sont pas suivies, cela peut
entraîner des blessures graves ou une intoxication
au monoxyde de carbone pouvant causer la mort,
si des produits de combustion s’infiltrent dans le
bâtiment.
Vérifier que toutes les ouvertures pratiquées dans
le mur extérieur autour du ou des tuyaux d’évent
(et de la prise d’air) sont scellées de manière à
empêcher l’infiltration de produits de combustion
dans le bâtiment.
Veiller à ce que la ou les sorties de l’évent de
l’appareil de chauffage (et la prise d’air) ne soient,
en aucune façon, obstruées, quelle que soit la saison
Safety markings are used frequently throughout this manual to
designate a degree or level of seriousness and should not be
ignored. WARNING indicates a potentially hazardous situation
that if not avoided, could result in personal injury or death.
CAUTION indicates a potentially hazardous situation that if
not avoided, may result in minor or moderate injury or property
damage.
WARNING:
The safety information listed below must be followed
during the installation, service, and operation of this
furnace. Failure to follow safety recommendations
could result in possible damage to the equipment,
serious personal injury, or death.
WARNING:
PROPOSITION 65 WARNING: This product contains
chemicals known to the state of California to cause
cancer, birth defects or other reproductive harm.
WARNING:
This furnace is not approved for installation in mobile
homes. Installing this furnace in a mobile home could
cause fire, property damage, and/or personal injury.
GAS SUPPLY & PIPING
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use
any phone in your building.
• Leave the building immediately.
• Immediately call your gas supplier from a
neighbors phone. Follow the gas suppliers
instructions.
• If you cannot reach your gas supplier, call the
fire department.
INSTALLATION AND SERVICE MUST BE PERFORMED
BY A QUALIFIED INSTALLER, SERVICE AGENCY OR
THE GAS SUPPLIER.
This furnace does not have a pilot. It is equipped with an
ignition device which automatically lights the burner. DO NOT
light the burner by hand.
IMPORTANT NOTE:
If the gas supply fails to shut off or if overheating occurs,
shut off the gas valve to the furnace before shutting off the
electrical supply!
En cas de température excessive, ou s’il est impossible de couper
l’alimentation en gaz, fermer le robinet manuel d’alimentation en gaz du
générateur d’air chaud avant de couper l’alimentation électrique
IMPORTANT SAFETY INFORMATION
4
WARNING:
It is imperative to maintain proper operation of the
venting system, including the masonry chimney (if
applicable). Insufficient venting could create the
production of excessive amounts of Carbon Monoxide
(CO) - a colorless, odorless gas that is produced during
incomplete combustion of any fuel. It can cause death
without warning. Carbon monoxide poisoning can
cause flu- like symptoms and also dizziness, fatigue,
headaches, nausea, and irregular breathing.
If you suspect that you are experiencing CO poisoning,
get fresh air immediately. Leave the home and call
for assistance from a neighbor’s home.
CAUTION:
This furnace requires unrestricted airflow for
combustion and ventilation. For proper and safe
operation, it is extremely important that the furnace
receives an unobstructed flow of clean, fresh air to
properly burn the fuel gas. If this flow of air is restricted,
the partially burned combustion gases may create
dangerous amounts of carbon monoxide that can
cause personal injury or death.
• Do not block or obstruct air openings on the furnace, air
openings or spacings around the furnace area or the room
or closet the furnace is in. Furniture and drapery should be
arranged so that the supply air registers and return grilles are
not obstructed.
• The U.S. Consumer Product Safety Commission (CPSC)
recommends every home have a Carbon Monoxide detector
in hallways near the bedrooms in each sleeping area. CO
detectors should be certified to the most recent requirements
of the UL, IAS OR CSA Standard and should be installed,
operated, and maintained in accordance with the detector
manufacturers instructions.
• If your furnace obtains its air through a pipe to the outdoors,
do not allow the inlet of the pipe to become blocked. If the
furnace is operated without adequate air for combustion, the
flame roll-out switch will open, turning off the gas supply to
the burners. This indicates that a serious problem with the
burners has occurred and must be corrected immediately.
Only a licensed HVAC technician can reset this switch.
• Before remodeling near the furnace, consult with a local code
official or the National Fuel Gas Code to make sure you will be
in compliance with supplying adequate air for combustion. By
erecting new walls, it is sometimes possible to inadvertently
restrict the furnace’s air supply. You can find more information
about supplying combustion air in the NFGC, which is available
at many libraries.
FILTER
WARNING:
Never operate the furnace without a filter in place.
Accumulating dust in the return air can build up on
internal components, resulting in loss of efficiency,
equipment damage, and possible fire.
Keep air filters cleaned. Clean or replace filter to maintain proper
airflow and achieve maximum efficiency. Refer to page 7 for
Maintenance & Inspection information.
CLEARANCES TO COMBUSTIBLES
WARNING:
Do not place combustible materials on or against
the furnace cabinet or within 6 inches of the vent
pipe. Furnace area must be kept clear and free of
combustible materials, gasoline and other flammable
vapors and liquids. A fire or explosion may result
causing property damage, personal injury or loss of
life. Failure to follow the safety warnings exactly could
result in serious injury, death or property damage.
The furnace is designed to have certain clearances to combustible
items such as wood, paper, etc. Some types of insulation are
combustible. If your furnace is installed in an attic, near unfinished
walls, or in other insulated space, keep area surrounding the
furnace free of insulating material.
SOURCES OF COROSION
It is known that certain common household chemicals can
cause heat exchanger corrosion if the vapors are pulled into
the furnace’s burners The following is a list of chemicals that
should not be used or stored near the furnace.
Do not store these chemicals near the furnace:
• Permanent wave solutions
• Chlorinated waxes and cleaners
• Chlorine based swimming pool chemicals
• Water softening chemicals
• De-icing salts or chemicals
• Carbon tetrachloride
• Halogen type refrigerants
• Cleaning solvents (perchloroethylene)
• Printing inks, paint removers, varnishes, etc.
• Hydrochloric acid
• Cements and glues
• Antistatic fabric softeners
• Masonry acid washing materials
FLOOD DAMAGE
WARNING:
Do not use this furnace if any part has been under
water. A flood damaged furnace is extremely
dangerous. Attempts to use the furnace can result in
fire or explosion. A qualified service agency should
be contacted to inspect the furnace and to replace all
gas controls, control system parts, electrical parts that
have been wet or the furnace if deemed necessary.
AVERTISSEMENT:
Ne pas installer ce générateur d’air chaud si l’une de ses pièces a
été immergée dans de l’eau. Un générateur d’air chaud endommagé
par une inondation est extrêmement dangereux. Toute tentative
d’utiliser le générateur d’air chaud peut entraîner un incendie
ou une explosion. Il faut communiquer avec un organisme de
service qualifié pour l’inspection du générateur d’air chaud et le
remplacement de toutes pièces électriques ou parties du système
de commande qui ont été mouillées ou immergées.
5
INTRODUCTION
Congratulations on the purchase on your new furnace! With
our dedication to quality, superior reliability, and outstanding
warranty, we know you will be pleased with this new appliance.
This furnace has been designed and built to provide many years
of safe and dependable home comfort, providing it is properly
installed and regular maintenance has been performed. Improper
use or insufficient maintenance can shorten the life of the furnace
and result in serious personal injury or property damage. Please
read this manual thoroughly and familiarize yourself with the
safety, operation and maintenance procedures for this furnace.
DO NOT DESTROY THIS MANUAL. KEEP IN A SAFE PLACE
FOR FUTURE REFERENCE.
Your furnace is designed to fulfill the requirements of being
classified as a Category IV furnace. This classification is related to
the furnace’s Annual Fuel Utilization Efficiency (AFUE) rating, the
percentage of fuel that is converted into usable heating energy.
The furnace components shown on page 6 will help to identify
and locate various parts of the furnace. The component you need
to familiarize yourself with is the gas valve. You will use this to
turn the furnace on and off. There are no user serviceable
parts. All repairs must be performed by a licensed HVAC
technician.
Category IV (Condensing) Furnaces
Category IV furnaces typically have an AFUE rating over 90%
and are mainly vented through plastic PVC pipe. These furnaces
also produce liquid condensate which is slightly acidic. The vent
pipe must be sloped upwards away from the furnace to properly
drain the condensate back to the condensate disposal system.
• Condensing type furnaces require condensate drain lines
to be properly installed by the installer. Depending on your
configuration, the drain lines may be routed out the left or
right sides of the furnace. These drain lines must maintain a
downward slope to ensure proper condensate drainage.
• Condensate must flow freely during furnace operation. The
homeowner must make sure the condensate drain lines do
not become blocked, pinched or crushed.
• If the furnace is installed in an area where temperatures
fall below freezing, special precautions must be made for
insulating condensate drain lines that drain to the outdoors.
If condensate freezes in the lines, this will cause the
condensate drain switch to shut down the furnace. Only
a licensed HVAC technician can reset this switch.
FILTER
WARNING:
Never operate the furnace without a filter in place.
Accumulating dust in the return air can build up on
internal components, resulting in loss of efficiency,
equipment damage, and possible fire.
• Air filter(s) are not supplied with the furnace as shipped
from the factory. The installer must provide a high velocity
filter and rack for a filter in the return air duct adjacent to the
furnace, or in a return air grill to the furnace.
• The furnace should always have a clean filter located either
at the air return on the furnace or in an air return register. If
the filter becomes dirty, it should be cleaned or replaced.
• New or newly renovated homes may require more frequent
changing until the construction dust has minimized. Filters
designed to remove smaller particles such as pollen, may
require additional maintenance.
• Always reinstall the doors on the furnace after servicing or
cleaning/changing the filters. Do not operate the furnace
without all doors and covers in place.
FURNACE LOCATION
If a furnace is installed in relatively small utility room or closet, the
installation needs openings in the walls or door to let combustion
air in. Make sure that these openings remain unobstructed.
Do not modify these openings in any way without consulting a
licensed HVAC technician.
If the furnace fails to operate check the following:
1. Is the thermostat setting correct?
2. Are the blower compartment door(s) in place?
3. Has the circuit breaker tripped or the control board fuse
burned open?
4. Is the gas turned on at the manual shutoff?
5. Is the filter dirty or clogged?
If the furnace still doesn’t operate, contact a licensed HVAC
technician
ABOUT THE FURNACE
TROUBLESHOOTING
6
Blower
Assembly
Blower Door
Switch
Burner
Assembly
Control Board
Flame
Sensor
Gas Manifold
Gas Valve
Igniter
Inducer Assemb
ly
Main Air Limit Switch
Pressure Switch
(Inducer)
Pressure Switch - Condensate
(‘B’, ‘C’, & ‘D’ cabinets only)
Roll-Out
Switch
Transformer
Vent Limit Switch
Finish
Flange
Finish
Flange
Blower Assembly
(behind blower panel)
Blower Door Switch
(behind
blower panel)
Burner
Assembly
Flame
Sensor
Gas Manifold
Gas Valve
Igniter
Inducer Assembl
y
Pressure Switch
Vent Limit Switch
Control Board
Main Air Limit Switch
Transformer
Roll-Out
Switch
Figure 1. *RC Series Upflow Furnace
Figure 2. *RL Series Downflow Furnace
COMPONENT LOCATIONS
7
STARTING THE FURNACE
1. Make sure the filter is clean and in place.
2. Make sure the vent system is properly installed.
3. Set the thermostat to the lowest setting.
4. Close the manual gas valve outside the furnace.
5. Turn off all electric to the furnace.
6. Remove the door from the burner compartment.
7. Turn the gas valve knob to the OFF position. See Figure 3
for gas valve knob location.
8. Wait 5 minutes. If there is any smell of gas, see “WHAT
TO DO IF YOU SMELL GAS” on page 3.
9. Turn the gas valve knob to the ON position.
10. Turn on all electric to the furnace.
11. Open the manual gas valve.
12. Turn the thermostat back up to force ignition.
13. Observe operation, including burners. If burners fail to ignite,
call a licensed HVAC technician.
14. Replace the door on the burner compartment.
SHUTTING DOWN THE FURNACE
IMPORTANT! IF YOU NEED TO SHUT DOWN YOUR
FURNACE FOR SERVICE OR MAINTENANCE, SHUT OFF
THE GAS VALVE TO THE FURNACE BEFORE TURNING
OFF THE ELECTRICAL SERVICE.
If your installation has a manual gas shutoff valve on the gas
supply pipe, shut this off, then shut off the electric to the furnace.
1. Set the thermostat to the lowest setting.
2. Close the manual gas valve outside the furnace.
3. Turn electric to the furnace off.
4. Open the door to the burner compartment.
5. Turn the gas valve knob to the OFF position.
6. Replace the door on the burner Compartment.
FURNACE AIR DUCTS
• The furnace should be inspected annually by a licensed HVAC
technician. Table 1 (page 8) contains suggested inspections
and frequency of maintenance.
• Homeowners should perform frequent visual inspections of the
furnace for obvious signs of deterioration. The furnace should
be secure without sagging, cracks gaps, etc around the base.
The return air duct connection(s) is secured and sealed to the
furnace cabinet and terminates outside the area containing
the furnace. Any signs of damage or loose connections should
be repaired by a qualified HVAC technician.
VENTING SYSTEM
• For proper and safe operation, this furnace requires
unrestricted airflow for combustion and ventilation. Inspect for
blocked or obstructed air openings on or around the furnace,
and the space around the furnace.
• The furnace venting system should be inspected annually by
a licensed HVAC technician. Vent pipe must slope upwards
and be physically secured without holes or corrosion. Any
corroded section of vent pipe must be replaced, and any
obstruction or blockage must be removed by the technician.
• Flue passageways, the vent system, and the burners should
be inspected and cleaned (if required) by a licensed HVAC
technician annually to ensure continued safe operation.
BLOWER & FILTER
• It is recommended that the blower compartment be cleaned
of dirt or lint that may have accumulated in the compartment
or on the blower and motor as part of the annual inspection.
• Keep air filters cleaned. It is recommended that the furnace air
filter be checked at least once a month. Clean or replace filter
to maintain proper airflow and achieve maximum efficiency.
• Furniture and drapery should be arranged so that the supply
air registers and return grilles are not obstructed.
BURNER OPERATION
Perform the startup instructions on page 10. The igniter should
ignite the closest burner and the flames should quickly carryover
to the other burners. The flames should be bright blue, with
occasional yellow streaks.
NEW CONSTRUCTION
The operation of gas furnaces in a construction environment can
cause a variety of problems with the furnace. Before occupying
the residence, homeowners should have these safety inspections
performed by a licensed technician:
• Before occupancy, the furnace shall be inspected and approved
by applicable local authority even if this results in redundant
inspections.
• The duct work must be inspected and cleaned if found to
contain any construction debris.
• The filter must be replaced or cleaned and the furnace must be
inspected by a licensed HVAC technician. The furnace must
be cleaned and/or repaired if found to be dirty, damaged, or
malfunctioning in any way.
STARTUP & SHUTDOWN MAINTENANCE & INSPECTION
N
A
T
N
A
T
OFF
ON
Figure 3. Gas Valve
Specifications & illustrations subject to change without notice or incurring
obligations (04/18). O’Fallon, MO, © Nortek Global HVAC LLC 2018.
All Rights Reserved.
708875B
(Replaces 708875A)
MAINTENANCE ITEMS
FREQUENCY OF MAINTENANCE
BEGINNING OF EACH
HEATING SEASON
END OF EACH
HEATING SEASON
MONTHLY
Verify furnace area is free of combustible materials. X X X
Verify combustion and ventilation air is not restricted. X X X
Verify no signs of physical deterioration of the furnace. X X X
Verify no obstructions or restrictions in vent or chimney. X X
Verify no holes or cracks in vent pipe. X X
Verify no corrosion in vent pipe. X X
Verify the horizontal vent pipes slope upwards away from furnace. X X
Verify burner flame. X
Clean or replace filter(s). X
Clean blower compartment. X
Clean burner assembly. X
Clean condensate collection & disposal system (if applicable). X
Table 1. Maintenance Table
-
1
-
2
-
3
-
4
-
5
-
6
-
7
-
8
