StyleCrest Installation Manual

22
FURNACE CONTROLS & FUNCTIONS
Furnace On / Off Switch: This switch turns electrical
power to the furnace on and off. The switch must be set
in the ON position for the furnace to operate. If blower
operation is not desired, the furnace On-Off switch may
be set in the Off position to cut the electrical power to the
furnace. See Figure 26 (page 15).
Limit Control: This furnace is protected by two high
temperature safety limit switches. The auxiliary (upper)
limit switch and the high temperature (lower) limit switch
are automatic reset types. If either limit trips, the burner
will shut off. If either limit switch trips off again soon after
resetting, set the furnace furnace On-Off switch to the
Off position and call your authorized serviceman. See
Figure 26.
Blower Off Delay: When the blower fan operates under
cooling mode, there is a 40 second delay after the call
for cooling (from the thermostat) is satisfied before the
blower turns off.
Gas Valve: The gas valves for the gas furnaces are a
100% shut-off type and will fail safe, if for some reason
the gas is turned off. The valve is a “slow-open” for MG1
models which means it opens to a low-fire position, and
after a few seconds, “steps-open” to high-fire.
Summer Cooling : The unit is equipped to use a 4-wire
thermostat. When using a 5-wire thermostat, RC and
RH should be jumped (see instructions included with
thermostat). NOTE: The MG1 furnace requires a Y
connection to the furnace. See Figure 31 (page 25).
MAINTENANCE
Installer Information
All furnaces need periodic service at the beginning of each
heating season. Call your qualified service contractor for
these items:
• Remove the air circulator and clean all dust and lint
from the unit with a stiff bristle brush.
• Inspect the combustion chamber blower compartment,
flue collar and Roof Jack.
• Check the gas valve (if applicable) and fuel line
connections for leaks.
• Make any adjustments necessary for good operation.
WARNING:
Use of furnace or air conditioning components
that are not included in the certification of
this appliance may create a hazard, invalidate
the certification, and in many states, make
installations illegal. Listed air conditioning
components are specified on the furnace label.
Figure 30. Without Coil Cavity Damper
Figure 29. With Coil Cavity Damper
OPTIONAL ACCESSORIES
Necessary when the furnace is used with packaged
air conditioners
If an air conditioner is installed that does not use the furnace
blower for air distribution and operates independently of
the furnace, the thermostat system must have an interlock
to prevent the furnace and air conditioner from operating
at the same time. This interlock system usually contains
either a “Heat-Cool” switch which must be turned to one
of the positions to activate heat or cool operation, or a
positive “OFF” switch on the cooling thermostat.
The furnace must also be equipped with an automatic
damper to prevent cold air from being discharged up around
the heat exchanger (p/n 901996 for furnaces without coil
cavity, or p/n 901083 with coil cavity). See Figure 29 or
Figure 30. Cold air may cause condensation inside the
heat exchanger which can rust and lead to early failure.
Optional Add-On Air Conditioning
Whether split system or single package, an energy-
saving air conditioner is available that has been designed
specifically for manufactured housing applications and can
best handle your home comfort needs. Ask your dealer or
contractor about add-on central air conditioning systems.
Single package unit includes cooling coils, compressor,
and vertical discharge fan. This type of unit connects with
the existing home air duct system (an optional close-off
damper is required with the furnace).
Split system unit with vertical discharge for quiet operation
connects with cooling coil furnace (optional coil cavity
required with “A” model furnaces).