MORTEX G18D SERIES Guide

MORTEX PRODUCTS INC 501 TERMINAL RD FORT WORTH, TX 76106 Page 1
DOWNFLOW ONLY For Installation In:
SINGLE STAGE GAS FIRED FURNACE 1. Manufactured (Mobile) Homes
MODELS: G18D SERIES 2. Recreational Vehicles
3. Modular Homes & Buildings
For installation only in HUD manufactured homes per Construction Safety 24 CFR Part 3280
USERS INFORMATION MANUAL
3 – Startup and Shutdown Instructions.......................................................... 6
4 – Homeowner/User Maintenance ................................................................. 8
5 – Troubleshooting .............................................................................................18
6 – Blower Performance......................................................................................23
7 – Accessories and Replacement Parts ........................................................23
8 – Wiring Diagrams .............................................................................................27
13 – Flue Box Assembly.....................................................................................................14
14 – Combustion Air Assembly..........................................................................15
15 – Blower Assembly ...........................................................................................15
16 – Component Locations .................................................................................16
17 – White Rodgers Gas Valve.............................................................................20
18 – Measuring Inlet (Supply) Gas Pressure...................................................20
19 – Measuring Outlet (Manifold) Gas Pressure ..........................................20
20 – Integrated Furnace Control Board...........................................................22
21 – Replacement Parts Identication.............................................................24
22 – Wiring Diagram – Heating Only Models................................................27
23 – Wiring Diagram – A/C Ready Models......................................................28
6 – Blower Performance Chart....................................................................................23
7 – Accessories................................................................................................................23
8 – Replacement Parts List ..................................................................................... 25
9 – Hight Altitude Gas Orice Chart..................................................................... 26
1 – Safety.....................................................................................................................2
2 – Homeowner/User Information ....................................................................5
1 – Safety.................................................................................................................. 10
2 – Furnace Maintenance .................................................................................. 11
3 – Furnace Controls ............................................................................................ 15
4 – Sequence of Operation ............................................................................... 17
The following list includes important facts and information regarding this gas furnace.
1. Furnace is rated at 115 VAC at 60 Hz.
2. Furnace is available in “Heating Only”or “A/C Ready”congurations.
3. Furnace is designed for use with cooling only or heat pump systems when a cooling coil cabinet and indoor coil is used. A/C
ready models are furnished with a cooling coil cabinet. The appropriate indoor coil must be selected and ordered separately.
4. A hold-down strap is furnished with furnace.
5. This furnace is designed for downow applications only.
6. This furnace must not be operated with the control box cover or front access panels removed.
7. This furnace is certied by ETL for use in the United States only.
SAVE THIS MANUAL FOR FUTURE REFERENCE
1 – Component Locations.....................................................................................4
2 – Burner Flame ......................................................................................................4
3 – Furnace Examination Checkpoints.............................................................5
4 – White Rodgers Gas Valve Components .....................................................7
5 – Gas Supply Line Piping and Shuto Valve Location.............................7
6 – Louvered Return Air Door - Outside ..........................................................8
7 – Louvered Return Air Door Filter Rack ...................................................................8
8 – Burner Assembly.........................................................................................................11
9 – Heat Exchanger Assembly w/ Baes ..................................................... 12
10 – 4”Combustion Air Tube Flange ................................................................ 13
11 – Top Cover Screws and Combustion Air Pan Screws .......................... 13
12 – Flue Box Cover Screws.................................................................................. 13
1 – Inlet Gas Pressure Range ................................................................................... 20
2 – Nominal Manifold Pressure........................................................................... 20
3 – Input Calculations For Cubic Foot Gas Meter........................................... 21
4 – Input Calculations For Cubic Meter Gas Meter........................................ 21
5 – Dip Switch Settings - Circ Blr Mtr Speeds & Htg Blower O Delay ..... 22
Manufactured and Distributed by: Mortex Products Inc www.mortx.com
501 Terminal Rd
Fort Worth, TX 76106
LIST OF SECTIONS - USERS INFORMATION MANUAL
LIST OF SECTIONS -SERVICE AND MAINTENANCE MANUAL
LIST OF FIGURES
LIST OF TABLES
CONTACT INFORMATION

MORTEX PRODUCTS INC 501 TERMINAL RD FORT WORTH, TX 76106 Page 2
SECTION 1: SAFETY
This is a safety alert symbol. When this symbol is seen on
labels or in manuals, be alert to the potential for personal injury.
Understand and pay particular attention to the signal words
DANGER, WARNING, or CAUTION.
DANGER: Indicates an imminently hazardous situation, which if
not avoided, will result in death or serious injury.
WARNING: Indicates a potentially hazardous situation, which if
not avoided, could result in death or serious injury.
CAUTION: Indicates a potentially hazardous situation, which if
not avoided, may result in minor or moderate injury. It is also
used to alert against unsafe practices and hazards involving
property damage.
Homeowners and furnace users must read all instructions
in this manual before performing any maintenance on this
furnace. This manual must be saved for future reference.
Safety Requirements
1. The furnace area must be kept clear and free of combustible
materials, gasoline and other ammable vapors and liquids.
2. Insulating material may be combustible. The furnace must be
kept free and clear of insulating material. The furnace area must
be examined when the furnace is installed in an insulated space
to make sure that insulation is away from the furnace.
3. Follow the instruction exactly as shown on the operating
instructions label, or the startup and shutdown instructions
located on page 7 of this manual to properly start the furnace or
turn the furnace o.
4. Should the gas supply fail to shut o or if overheating should
occur, shut o the manual gas cock located on the gas pipe
before turning o the electrical power supply to the furnace.
5. Do not use this furnace if any part has been under water as
a ood damaged furnace is extremely dangerous to operate.
Attempts to use the furnace could result in a re or explosion.
A qualied service agency should be contacted to inspect
the furnace and replace all gas controls, control systems, and
electrical parts that have been wet. In some cases, the damage
may be so severe that the furnace may need to be replaced.
6. Flammable materials, solvents, or other volatile liquids should
be stored only in approved containers outside the home. These
materials vaporize easily and are extremely dangerous.
7. Do not store cleaning materials near the furnace. Materials such
as bleaches, detergents, powdered cleaners can cause corrosion
of the heat exchanger and premature failure.
8. Do not use the area around the furnace as a storage area for
items that could block the normal ow of air to the furnace.
This ow of air is required for ventilation of the various furnace
components.
CAUTION
CAUTION
This furnace requires periodic routine maintenance and
cleaning of the exterior surfaces by the homeowner or user
to remove dust and debris. Any additional service or repair
must be performed by qualied personnel. This furnace
must be serviced and maintained as specied in these
instructions and any applicable local, state, and national
codes including, but not limited to building, electrical, and
mechanical codes.
Any adjustment, service, or maintenance by the
homeowner or user may create a condition where the
operation of the product could cause property damage,
personal injury, and death.
Only qualied service personnel or installer may refer to
the service and maintenance section of this manual for
serving or repairing this furnace.
FIRE OR EXPOLSION HAZARD
This furnace is designed and approved for use with Natural
Gas or Propane (LP) only. Do not burn any liquid fuel or
solid fuel in this furnace.
Burning any unapproved fuel in this furnace will result in
damage to the furnace heat exchanger which could result
in a re, personal injury, property damage, and loss of life.
Burning any unapproved fuel in the furnace will result in
termination of the factory warranty.
FIRE AND ELECRTRICAL HAZARD
Failure to follow the safety warnings in this manual and in
the furnace labels could result in a re or electrical hazard
which may cause property damage, personal injury, or
death.
• Do not store or use gasoline or other ammable 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 gas appliance.
• Do not touch any electrical switch.
• Do not use any phone in your building, including cell
phones.
• Leave building immediately.
• Call your gas supplier from a neighbor’s phone. Follow
the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the re
department.
• Instruction and service must be performed by
aqualied installer, service agency or gas supplier.

MORTEX PRODUCTS INC 501 TERMINAL RD FORT WORTH, TX 76106 Page 3
FIRE OR ELECTRICAL HAZARD
Failure to follow the safety warnings could result in a re
or electrical hazard which may cause property damage,
personal injury, or death.
This furnace must not be installed where it may be
exposed to potentially explosive or ammable
atmosphere. Installing this furnace in an explosive or
ammable atmosphere may result in a re or explosion
causing property damage, personal injury, or death.
HAZARD OF ASPHYXIATION: Negative pressure inside
a closet with closet door closed and the furnace blower
operating must not be more than 0.05”W.C.
To prevent premature heat exchanger failure, do not locate
any gas-red appliances in area where corrosive vapors
are present in the atmosphere. Refer to the section on
COMBUSTION AIR QUALITY.
Because of the potential of odorant fade, a gas leak may
not be detected by smell. It is recommended that black
iron pipe be used from the furnace gas valve to outside
the home in order to prevent gas leaks inside the home.
Copper and brass tubing and ttings (except tin lined)
must not be used if the gas contains more than a trace
(0.3 grains per 100 cubic ft.) of hydrogen sulde gas.
Check with the gas supplier about gas content and for
a gas leak detector.
This furnace must not be installed where it may be
exposed to potentially explosive or ammable atmosphere.
Installing this furnace in an explosive or ammable
atmosphere may result in a re or explosion causing
personnel injury, property damage, or death.
D
D
ANGER
ANGER
ELECTRICAL OR EXPLOSION HAZARD
Do not use this furnace if any part has been under water.
A ood damaged furnace is extremely dangerous.
Attempts to operate a ood damaged furnace may result in
a re.
A qualied contractor, installer, or service agency must be
contacted to inspect the furnace for any water damage and
replace components, controls, or electrical parts that have
been damaged or replace the furnace.
D
D
ANGER
ANGER
USE ONLY NATURAL GAS OR HD-5 PROPANE
FUEL IN THIS FURNACE.
DO NOT USE “COMMERCIAL GRADE PROPANE”
OR ANY PROPANE BLEND OTHER THAN HD-5.
IF A FUEL OTHER THAN NATURAL GAS OR HD-5
PROPANE IS USED IN THIS FURNACE, YOUR
WARRANTY WILL BE VOID.
COMBUSTION AIR QUALITY
(LIST OF CONTAMINANTS)
This furnace requires 100% outdoor air for combustion. This
furnace must not be installed in the following environments.
• Restricted environments
• Buildings with indoor pools
• Laundry rooms
• Hobby or craft rooms
• Chemical storage areas
• Chemical Exposure
The furnace must not be exposed to the following substances and
chemicals.
• Permanent wave solutions
• Chlorinated waxes or cleaners
• Chlorine based 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
• Hydrochloric acid
• Cements and glues
• Antistatic fabric softeners
• Masonry acid washing materials
The combustion air intake pipe termination must be located
external to the building and in an area where there is no exposure
to the substances listed above. Any exposure to the substances
listed above will void the furnace warranty.

MORTEX PRODUCTS INC 501 TERMINAL RD FORT WORTH, TX 76106 Page 4
Do no wet electronic components or wire connections
during the gas leak test. Wetting electronic components
may damage circuitry and wire connections and can cause
a hazardous situation.
Dry moisture from all leads and terminals if wetting does
occur.
Wait at least 12 hours for the electronic components and
wire connections to fully dry before energizing the furnace.
This furnace area must never be used as a broom closet, for
any other storage purposes or allow the furnace to come in
contact with the following substances.
1. Spray or aerosol cans, rags, brooms, dust mops, vacuum
cleaners, or other cleaning tools.
2. Soap powders, bleaches, waxes, other cleaning
compounds, plastic items or containers
3. Gasoline, kerosene, cigarette lighter uid, dry cleaning
uids, or other volatile uids.
4. Paper bags, boxes, or other paper products.
FIRE OR ELECTRICAL HAZARD
Servicing the furnace can be hazardous due to exposure
to electrical components. Only trained and qualied
personnel are allowed to service or repair this furnace. The
homeowner or user must never attempt to service or repair
this furnace.
The homeowner or user may perform only basic
maintenance functions such as cleaning of exterior
surfaces and replacing the air lters.
Observe all precautions in the manuals and on the
attached labels when performing maintenance on this
furnace.
Figure 1: Component Locations
Figure 2: Burner Flame

MORTEX PRODUCTS INC 501 TERMINAL RD FORT WORTH, TX 76106 Page 5
EXAMINING THE FURNACE
It is the homeowner’s or user’s responsibility to ensure that an
annual inspection of this furnace is made by a qualied service
agency. The qualied service agency must examine the furnace as
outlined in steps below before each heating season.
1. Examine the heat exchanger, vent pipe, combustion air
passages, vent connectors and chimney to be sure they are
clear and free of obstructions.
2. Examine the vent pipe making sure it is rmly in place, that it
is attached to the top of the furnace and it is physically sound
without holes and all of the connections are secure.
3. Examine the return air louvered door to make sure it is
physically sound, fastened securely to the furnace casing.
4. Examine the furnace casing making sure the physical support is
sound without sagging, cracks, or gaps.
5. Examine the furnace base making sure it is physically sound
without cracks, gaps, or sagging and that it has a good seal to
the casing.
6. Examine the furnace casing for obvious signs of deterioration.
7. Examine the burner ame to make sure the burner is adjusted
properly. The ame should appear long and cylindrical with a
blue color. Some yellow streaks may appear, especially near the
tip of the ame. The ame on a furnace operating on propane
(LP) will appear less blue and has considerably more yellow
streaking.
Figure 3: Burner Flame
SECTION 2: HOMEOWNER/USER INFORMATION
How the Furnace Works
Heating Cycle
1. The thermostat calls for heat which energizes furnace control
board“W”terminal.
2. The combustion air blower is energized for a pre-purge period
to remove any remaining gases from the heat exchanger and
will send those gases out the exhaust vent.
3. After the pre-purge period, the combustion air proving
pressure switch electrical contacts close if there is no exhaust
vent restriction.
4. After the pressure switch contacts closes, the hot surface igniter
is energized and will glow.
5. After the igniter has time to become suciently hot, the gas
valve will open and allow gas to ow to the burner. The gas will
ignite as it passes by the igniter and a ame will be established.
The ame sensor will sense the presence of ame and send
a signal back to the control board that a ame is present. The
control board will keep the gas valve open as long as the ame
sensor detects the presents of a ame and there is a call for heat
by the thermostat unless one of the 2 limit switches senses an
over-temperature condition.
6. After ignition has been established long enough for the heat
exchanger to heat up, the circulating blower motor will be
energized which distributes warm air throughout the home.
7. When the temperature of the home has reached the
temperature setting on the thermostat, the 24 VAC signal will be
removed from the “W” terminal on the control board which
causes the gas valve to de-energize and the burner ame to
extinguish. The circulating blower motor will shut down after
the heat exchanger has suciently cooled down.
8. The furnace will then be in “stand-by” mode until there is
another call for heat.
The furnace is equipped with the components and controls
necessary for proper and safe operation and identied in Figure 1.

MORTEX PRODUCTS INC 501 TERMINAL RD FORT WORTH, TX 76106 Page 6
General Homeowner/User Information
1. Refer to the furnace rating plate for the furnace model number
and specications for safe operation.
2. Provide clearance for service access to the burner
compartment, control box, and the blower compartment.
3. Failure to carefully read and follow all of the instructions in
this manual can result in malfunction of the furnace, property
damage, personal injury, or death.
4. If the furnace is installed in a residential garage, it must be
installed so the burner is located not less than 18 inches above
the oor and the furnace must be located or protected to avoid
physical damage by vehicles.
The Service Technician
A qualied service technician is required to perform any service
or repairs on the furnace. If the furnace gives any indication
of improper operation, call the service technician. The service
technician is allowed to perform the normal routine care of your
furnace as well as service and repairs and can detect potential
problems and make corrections before trouble develops.
Preventative maintenance of this type will allow the furnace to
operate with minimal concerns to the homeowner or users and
will add years of reliable comfort.
Warranty and Responsibilities
It is the responsibility of the homeowner to make certain the
furnace has been properly installed and adjusted to operate
properly.
The manufacturer warrants the furnace to be free from defects
in material or workmanship for a stated time in the warranty
agreement. The manufacturer will not be responsible for any
repair costs to correct problems due to improper setup, improper
installation, improper furnace adjustments, adding parts that
are not listed by the manufacturer for use with the furnace, and
improper operating procedures by the homeowner or users.
Specic examples of service calls which will be excluded from
warranty reimbursement are:
1. Correcting faulty duct work due to too few ducts or ducts that
are too small to provide proper air ow through the furnace.
2. Correcting wiring problems in the electrical circuit to the
furnace.
3. Resetting circuit breakers or on/o switches used for servicing.
4. Furnace problems caused by installation and operation of any
air conditioning unit, heat pump, or other air quality devise
which is not approved for use with this furnace.
5. Adjusting or calibrating the thermostat.
6. Problems caused by construction debris which has fallen into
the furnace.
7. Replacement of fuses.
8. Problems caused by dirty air lters.
9. Problems caused by restrictions in the return or supply air ow
causing low air ow.
The home owner should establish a thorough understanding of
these responsibilities with the installer or service company to
prevent misunderstandings at a later time.
While Homeowner or User is Away From Home
The furnace is equipped with safety shuto devices which will
shut o the gas burner in case of a malfunction. For this reason, it
is never practical to assume the furnace will operate unattended
for a long period of time.
If the homeowner or user is planning to be away from home for
a long period of time, someone should be asked to check on the
home every day especially when the outside temperature may fall
below 35°F to ensure the furnace is operating properly to prevent
water pipes from freezing.
When to Call For Service Assistance
Very often time can be saved if the service agency is given
information about a furnace problem ahead of time. This will
enable the service agency to possibly identify the source of
the problem prior to the service call and determine the specic
replacement components that may be required so the service
agency can arrive with the parts to x the problem.
SERVICE AGENCY INFORMATION
Fill in Below
MODEL NUMBER:
SERIAL NUMBER:
SERVICE COMPANY:
ADDRESS:
TELEPHONE (DAYTIME):
TELEPHONE (EMERGENCY)
NOTES:
Failure to follow these instruction exactly may result in
a re or explosion which can cause property damage,
personnel injury, and / or loss of life.
SECTION 3: STARTUP AND SHUTDOWN
INSTRUCTIONS
Safety Information
Read the safety instructions below before trying to start the
furnace.
1. This furnace does not have a pilot light. It is equipped with an
ignition device which automatically lights the burner. Do not
try to light the burner by hand.
2. Before starting the furnace, smell around the furnace area for
gas. Be sure to smell next to the oor because some gases are
heavier than air and will settle on the oor.
3. Only use a nger to push the gas control switch to the “ON”
position. Never use tools. If the switch will not operate by hand,
don’t try to repair it. Call a qualied service technician. Force or
attempted repair may result in a re or explosion.
4. Do not use this furnace if any part has been under water.
Immediately call a qualied service technician to inspect the
furnace and replace parts and controls that have been under
water.

MORTEX PRODUCTS INC 501 TERMINAL RD FORT WORTH, TX 76106 Page 7
Starting the Furnace
1. STOP! Read the safety information above.
2. Set the thermostat mode to“OFF”.
3. Turn o the electric power to the furnace.
4. Remove the furnace access panel.
5. Move the gas control switch to the“OFF”position. Do not
force it. See Figure 4 for the switch location.
6. Wait 5 minutes to clear out any gas. If gas is smelled, follow
Step 2 in the safety information above. If there is no gas
smell, go to Step 7 below.
7. Move gas control switch to the“ON”position. Do not force it.
See Figure 4 for the switch location.
8. Replace the burner access panel.
9. Turn on electrical power to the furnace.
10. Set the thermostat mode to“HEAT” and the temperature
setting above the room temperature. Burner will typically
light after 30-60 seconds, but it may take multiple tries due to
air in the gas line. The furnace will attempt to light the burner
3 times before it will lock out for 1 hour at which time it will try
to light again.
11. If the furnace will not light, follow the instructions“Shutting
the Furnace O” below.
Shutting the Furnace O
1. Set the thermostat mode to“OFF”.
2. Turn o the electrical power to the furnace if service is to be
performed.
3. Remove furnace access panel.
4. Move gas control switch to the“OFF”position.
5. Replace burner access panel.
The Furnace Fails to Operate Properly
If any abnormalities are observed while the furnace is operating,
perform the following checks:
1. Check the setting on the thermostat to make sure the
thermostat is set above the room temperature.
2. Check to see if the electrical power is turned on at the circuit
breakers at the main electrical panel (circuit breaker box) or
check any on/o switches that may be used for service
disconnect switches.
3. Make sure the air lters are clean, return grilles are not
obstructed, and supply air registers are open.
4. Make sure the control switch on the gas valve is in the
“ON” position. Refer to Figure 4 for the gas valve control switch
location.
5. Make sure the gas cock or valve shown in Figure 5 is in the
“ON” position.
If the cause of the malfunction is not obvious, do not attempt
to repair the furnace. Call a qualied service agency to repair
the furnace.
Should overheating occur, turn the gas cock or gas valve
in the gas supply line to the “OFF”position. After the
furnace has cooled o, turn the circuit breakers in the main
electrical panel (circuit breaker box) to the “OFF” position.
Call a qualied service personal to troubleshoot and repair
the furnace. Do not allow the furnace to continue to cycle
on the overtemperature limit switches.
Figure 4: White Rodgers Gas Valve Components
Figure 5: Gas Supply Piping & Shuto Valve Location

Pull the top out to remove
Air Filters are located on the back of this door
MORTEX PRODUCTS INC 501 TERMINAL RD FORT WORTH, TX 76106 Page 8
This furnace requires maintenance at the beginning of each heat-
ing season to assure proper operation. The annual service must be
performed by qualied service technician. The homeowner/user
is expected to perform general cleaning of the exterior surfaces,
clean dust from the louvers in the return air door, and replace-
ment of the air lters. Air lters must be checked every month
and replaced as needed. Figures 6 and 7 show the location of the
air lters in the louvered return air door. If the louvered return air
grille does not contain lters, the return air lters may be located
in a return air lter grille on the closet wall.
Before proceeding, make sure the area is well ventilated.
Turn the thermostat mode to“OFF”. If the circulating
blower is running, wait until it stops automatically. Follow
the “Shutting the Furnace O” instructions located in
Section 3: Startup and Shutdown Instructions on page
7 of this manual. Check all metal parts and surfaces to
make sure they have cooled to room temperature before
performing maintenance on the furnace.
SECTION 4: HOMEOWNER/USER MAINTENANCE
Figure 6: Louvered Return Air Door - Outside
Figure 7: Louvered Return Air Door Filter Rack
(Requires Two 16” x 20” x 1” High Velocity Air Filters)
Every time the lters are changed, the following items should be
visually inspected.
• Check combustion air and vent pipe for blockage.
• Check for leaks in the vent pipe.
• Check for dirt or lint on any surfaces or on components.
Do not try to clean any of the surfaces or components or try to
repair or replace any components. Cleaning of the furnace and
its components and repairing or replacing components must be
done by a qualied service professional.
• Check for excessive amounts of dirt and lint on components.
• Check for obvious damaged or deteriorated components or
surfaces.
• Check for water on any surface inside or outside of the furnace.
If during the visual inspection of the furnace any of the above
conditions are found, do not operate the furnace. Call a qualied
service technician to check, clean, or repair the furnace. The
service technician can provide additional information or answer
questions about the operation of the furnace and why the furnace
must be checked or cleaned.
If all components appear to be in good operating condition,
replace the front panels and follow the “Starting the Furnace”
instructions in Section 3: Startup and Shutdown Instructions on
page 7 of this manual.
Replacing Air Filters in the Louvered Return Air Door
All models require two 16”x 20” x 1” high velocity pleated air
lters which are located in the louvered return door on the front
of the furnace.
Follow the steps below to replace the air lters located in the
furnace louvered return air door.
1. Follow the procedure“Shutting the Furnace O” in Section 3:
Startup and Shutdown on page 7 of this manual.

MORTEX PRODUCTS INC 501 TERMINAL RD FORT WORTH, TX 76106 Page 9
2. Pull back on the top of the return air grille door until it pops
out of the retainer clip.
3. Let the top of the door fall outward and then lift up slightly
and outward and set the door on the oor.
4. Remove the center retaining bracket by pushing down on the
left side of the bracket then use a small at blade screwdriver
to pry it out.
5. Remove both air lters from the door. These lters are
disposable lters. Do not attempt to clean the lters and reuse
them.
6. Insert the replacement air lters in the door.
7. Place the center retaining bracket between the 2 air lters.
Slide the bracket under the ange on the left side of the door.
Place a at blade screwdriver between the bracket and
the right side door ange and slide the bracket past the door
ange until the bracket is back into place. Use a rubber mallet
to straighten the right side door ange if necessary.
8. Lift the door up against the cabinet and align the slots in the
bottom of the door with the tabs on the divider panel.
9. Push the door forward lining up the plastic door strike in the
top cover with the hinge in the door.
10. Push the top of the door on the left side forward until the door
strike snaps into the latch.
11. Push the top of the door on the right side forward until the
door strike snaps into the latch.
Follow the “Starting the Furnace” instructions in Section 3:
Startup and Shutdown Instructions on page 7 of this
manual.
Optional Return Air Filter Grille
Some installations may utilize one or more eld supplied return
air lter grilles that has been installed in the closet or alcove wall
above the furnace. If there are no lters in the furnace louvered
return air door, look for a return air lter grille or grilles on the wall
the closet or alcove. To replace the lters in a return air lter grille,
turn the thumbscrews or levers on the face of the grille door and
allow the grille door to fall outward providing access to the lter.
Replace the air lter in the return air lter grille with the same size
and type lter that was removed. Once the new lter is in place,
close the grille door and secure it with the thumbscrews or levers.

MORTEX PRODUCTS INC 501 TERMINAL RD FORT WORTH, TX 76106 Page 10
SERVICE AND MAINTENANCE MANUAL
THE HOMEOWNERS AND FURNACE USERS MUST STOP HERE!
This section has been designed to assist a qualied service
agency in performing service and maintenance on this furnace.
Homeowners or furnace users must never attempt to perform
maintenance or service on this furnace, especially when furnace
components must be replaced or adjusted.
The furnace manufacturer is not responsible for damage
to the furnace or furnace malfunctions due to improper
parts changes, improper maintenance, improper furnace
adjustments, or improper modications made by the
homeowner or furnace user.
The furnace manufacturer is not responsible for damages,
repairs, or injury if the homeowner or furnace user uses
this section of the instructions in an attempt to perform
maintenance or repairs to the furnace. This practice is very
dangerous and may result in property damage, personal
injury, or death due to a re, explosion, or electrical shock.
If the homeowner or the furnace user attempts to perform
any maintenance or repairs to this furnace, the warranty
will be voided and the homeowner will be responsible for
all repair costs and/or damages.
Improper adjustment, service or maintenance may create a
condition where the operation of the product could cause
property damage, personal injury, or death.
FIRE OR ELECTRICAL HAZARD
Failure to follow the safety warnings in this manual or on
labels axed to the furnace may result in a re or electrical
hazard which may cause property damage, serious injury,
or death.
This is a safety alert symbol. When this symbol is seen on
labels or in manuals, be alert to the potential for personal injury.
Understand and pay particular attention to the signal words
DANGER, WARNING, or CAUTION.
DANGER: Indicates an imminently hazardous situation, which if
not avoided, will result in death or serious injury.
WARNING: Indicates a potentially hazardous situation, which if
not avoided, could result in death or serious injury.
CAUTION: Indicates a potentially hazardous situation, which if
not avoided, may result in minor or moderate injury.It is also
used to alert against unsafe practices and hazards involving
property damage.
The following safety rules must be followed when servicing
this furnace.
CAUTION
CAUTION
This product must be serviced and maintained as specied
in these instructions and to any applicable local, state,
and national codes including, but not limited to building,
electrical, and mechanical codes.
SAFETY REQUIREMENTS
1. This gas red furnace is powered by a 115 volt, 60 Hz electrical
supply circuit. Check each electrical circuit with a meter to
be sure the power has been disconnected before servicing the
furnace.
2. Insulating materials may be combustible. This furnace must be
kept free and clear of insulating materials.
3. Follow the instructions in Section 3: Startup and Shutdown
Section of the User Information Manual to properly start or
shut the furnace o.
4. Make sure all moving parts have come to a complete stop
before the furnace door is removed to perform service or
maintenance. Moving parts can cause serious injury or death if
clothing or body parts get caught in the moving parts.
SECTION 1: SAFETY
ELECTRICAL SHOCK AND FIRE HAZARD
• Failure to follow the safety warnings in the manual or
on the labels axed to the furnace may result in property
damage, serious injury, or death.
• Improper servicing could result in property damage,
serious injury, or death.
• Placing jumper wires between the RED and WHITE
thermostat wires at the furnace in order to bypass the
thermostat and energize the heater is an extremely
dangerous practice that can result in damage to the
thermostat, property damage, serious injury, or death.
• Before servicing, disconnect all electrical power to the
furnace.
• When servicing controls, label all wires prior to
disconnecting to aid in proper reconnection of wires.
• Verify proper operation after servicing by turning the
thermostat above the room temperature for a brief period
of time to ensure future operation.