MORTEX
PRODUCTS
INC
501
TERMINAL
RD
FORT
WORTH,
TX
76106
Page
10
1.
Cut a rectangular opening in the plenum base. A sheet metal
plate can be made that completely covers the opening in the
base.
2.
The plate must be secured with screws and sealed to prevent
leaks.
3.
The coil cabinet doors can be removed to inspect the heat
exchanger on most Manufactured (Mobile) Home Downflow
Appliances.
Closet Installation
This furnace is approved for use in an alcove with both the heating
only (without an air conditioning coil) and the A/C ready models. A
minimum of 6” front clearance to a face wall or partition is needed
for service access and return air clearances.
Air filter Size – All Models take two (2) - 16” x 20” x 1”.
Prior to installing the furnace make sure the holes are cut into the
floor for the refrigerant tubing, the electrical wiring is in place, the
thermostat wiring and the condenser control wiring is in place.
Follow the sixteen steps above for installing the furnace.
FILTERS
Alcove Installations
All applications require the use of an internal filter. All filters
mounting provisions are factory supplied as part of the louvered
return grille door.
Closet Installations
All furnaces are shipped with air filters located in the return air
louvered door. It is permissible to remove the filters from the return
air louvered door and use a return filter grille that has been installed
into the wall above the furnace and has a sufficient size so it does
not restrict the return airflow. The recommended filter sizes for the
return air filter grille are shown below for throwaway filters that are
rated for a velocity of 300 feet/minute (91.44 m/minute):
1,200 CFM requires a 20 inch x 30 inch filter size.
1,600 CFM requires a 20 inch x 40 inch filter size.
1,800 CFM requires a 25 inch x 30 inch filter size.
2,000 CFM requires a 25 inch x 40 inch filter size.
The recommended filter sizes for the return air filter grille are
shown below for pleated air filters that are rated for a velocity of
500 feet/minute (152.4 m/minute):
1,200 CFM requires a 20 inch x 20 inch filter size.
1,600 CFM requires a 20 inch x 25 inch filter size.
1,800 CFM requires a 20 inch x 30 inch filter size.
2,000 CFM requires a 16 inch x 40 inch filter size.
IMPORTANT:
Throw away air filters with a rated velocity of 300
feet per minute (91.44 m/minute) cannot be used on the furnace
return air louvered door because the air velocity is too high and will
destroy the filter. The filter velocity with this furnace is 400 feet per
minute (121.92 m/ minute). Do not use a filter that is rated for less
than 400 ft/min (121.92 m/minute).
Never use a filter deeper that 1 inch (2.54 cm) or a filter that has a
large pressure drop. This pressure drop will cause the appliance
airflow to be reduced causing the appliance temperature rise to
increase causing reduced efficiency and higher heat exchanger
temperatures. If the appliance does not operate within the specified
rise range on the name plate or the limit is cycling, then you must
change the air filter to a bigger size or reduce the thickness in order
to reduce the pressure drop across the air filter.
DOWNFLOW COOLING COIL CABINET
The cooling coil cabinet is supplied with the A/C Ready models.
The cabinet is 25.5 inches (64.77 cm) tall. The base of the cooling
coil cabinet can be mounted directly to the duct connector and
attached with screws. Make sure all of the openings in the furnace
base matchup with the openings in the duct connector, especially
the supply air opening. You can remove the coil cabinet doors in
order to confirm that all the holes in the base line up with the holes
in the duct connector. A combustible floor base is not required
when using a cooling coil cabinet.
Line up the duct openings and secure the coil cabinet to the
floor before installing the cooling coil.
OUTDOOR AIR ACCESSORY
A replacement furnace may have a blend air accessory that supplies
fresh air from outside through a 4 inch (10.16 cm) pipe that attaches
to the top cover of the appliance. There is a knockout and four
screw holes are located in the top cover of the appliance for the
attachment of a blend air damper or tube assembly. Refer to Figure
10 for knockout and screw hole locations.
Figure 9: Outdoor Fresh Air Intake Knockout
SECTION IV: GAS SUPPLY AND VALVE
CONNECTIONS
All field installed gas piping must be pressure tested for
leaks prior to operation of the appliance. Never test for gas
leaks with an open flame. Use a commercially available
soap solution made specifically for detection of leaks. Be
sure to check all connections.
Failure to properly check all connections for leaks or failure
to check any connections for leaks may result in a fire or
explosion causing property damage, personal injury or loss
of life.
