All installations and services must be performed by qualified service personnel.
24
Figure 8
M. SETTING TEMPERATURE RISE
The GMD1-60N and GMD1-80N is designed and wired at the factory for a heating
blower speed that should result in an approximate temperature rise of 70
°
F.
The blower motor is wired on low speed for heating mode of the GMD1-60N.
The blower motor is wired on medium low speed for heating mode of the GMD1-80N.
The temperature rise through the furnace may vary depending on the duct system,
elevation, heating value, etc. for each installation.
After 10 to 15 minutes of continuous operation, the temperature rise through the
furnace must fall within a range of 55
°
F to 85
°
F. If the outlet or supply duct
temperature is too high, check to make sure the return air filter is clean, the return air
registers are free from obstruction, the outlet registers are properly adjusted and clear,
and the supply and return air ducts are open.
The circulating air blower is not moving enough air if the supply air temperature is still
too high. Before proceeding further, turn off the power supply to the furnace and
remove the blower door. The speed of the blower must be increased by changing the
speed tap from the motor (see wiring diagram). This is accomplished by locating the
control panel attached to the blower housing and switching the blower lead, which
should be connected to the “Heat” terminal on the White-Rodgers 50A65-143 control,
with one of the higher speed blower leads attached to a terminal marked “Park”. Be
sure to attach any unused blower leads to a terminal marked “Park”. Replace the
blower door and turn on the power supply.
