Service manual

129099-UUM-F-0507
Unitary Products Group 3
GAS SUPPLY
The gas supply to your home will either be Natural Gas or Propane gas.
Your furnace will be factory equipped to operate on only one of these
two different gases.
A small metal tag secured to the furnace next to the gas valve will spec-
ify the type of gas your furnace is equipped to use.
If the gas is different from that specified on the metal tag, the furnace
can be converted by following the instructions on the furnace safety
label inside lower front panel. Parts for conversion are contained in the
small bag attached to the gas valve. Be sure the proper size orifice is
used, as specified on the furnace name plate.
Natural Gas Operation
The furnace is designed for 7" W.C. inlet pressure. Pressure is reduced
to 3 1/2" W.C. by the pressure regulator in the gas valve.
Propane Gas Operation
Inlet pressure to the gas valve must be 11" W.C. When properly con-
verted to Propane gas, the pressure is regulated at 10" W.C.
INSTRUCTIONS FOR EXAMINING THE FURNACE
INSTALLATION
It is the owner’s responsibility to ensure that an annual inspection of the
entire heating portion of the unit is made by a qualified service agency.
Examine the furnace as outlined below in steps “1 - 6” before each
heating season.
1. Examine the heat exchanger, through an access panel located on
the supply air plenum. Visually examine the exterior sections of
the vent/combustion air piping and the vent connectors to be sure
that they are physically sound without holes or excessive corro-
sion.
2. Examine the vent pipe making sure it is firmly in place, and is
physically sound without holes and all of the connections are
secure.
3. Examine return connections for Modular or Manufactured (Mobile)
Homes.
4. Examine the return air filter rack connections to make sure they
are physically sound, sealed to the furnace door.
5. Examine the furnace casing making sure the physical support is
sound without sagging, cracks or gaps. Examine the furnace base
making sure it is physically sound without cracks, gaps or sagging
and has a good seal.
6. Examine the furnace casing for obvious signs of deterioration.
7. Examine the burner flames to make sure the burner look like they
are operating properly. The burner flames for natural gas should
appear blue with a few yellow tips. The burner flames for propane
gas should appear blue with moderate yellow tips. The flame
should appear cylindrical in shape and should extend from the end
of the burner into the heat exchanger.
Observing Burner Operation
1. Observe burner to make sure it ignites. Observe color of flame. On
natural gas the flame will burn blue with appreciably yellow tips.
On Propane gas a yellow flame may be expected. If flame is not
the proper color call a qualified service technician for service.
2. Let furnace heat until blower cycles on.
3. Turn thermostat down.
4. Observe burner to make sure it shuts off.
5. Let the furnace cool and blower cycle off.
If any abnormalities are observed when checking for correct operation,
such as burner failing to ignite or to turn off, sooty flame, etc., call your
nearest authorized service technician as shown in the Service Center
List included in the home owner envelope with the furnace.
If Furnace Fails to Operate Properly
1. Check setting of thermostat - and position of HEAT/COOL switch if
air conditioning is installed. If a set-back type thermostat is
employed be sure that the thermostat is in the correct operating
mode.
2. Check to see that electrical power is ON.
3. Check to see that the knob or switch on the gas control valve is in
the full ON position.
4. Make sure filters are clean, return grilles are not obstructed, and
supply registers are open.
5. Be sure that furnace flue piping is open and unobstructed.
If the cause for the failure to operate is not obvious, do not attempt to
service the furnace yourself. Call a qualified service agency or your gas
supplier.
The furnace must be converted by a qualified technician.
Improper conversion can cause unsafe operation, explo-
sion, and/or fire or asphyxiation.
FIGURE 2: Burner Flame Appearance
Should overheating occur, or the gas supply fail to shut off, shut
off the manual gas valve to the furnace and allow blower to run
until furnace cools down and blower shuts off before shutting off
the electrical supply.
NATURAL GAS
PROPANE GAS
LIGHT BLUE
WITH YELLOW TIPS
DARK BLUE
BLUE TIPS JUST
STARTING TO
BECOME
PRONOUNCED
WHITISH YELLOW
TO LIGHT YELLOW
LIGHT BLUE
BLUE TIPS JUST
STARTING TO
BECOME
PRONOUNCED