All installations and services must be performed by qualified service personnel.
27
Figure 8
M. SETTING TEMPERATURE RISE
The furnace is designed and wired at the factory for a heating blower speed that should
result in an approximate temperature rise of 60
F for a GMD2-60N or 70
F for a GMD2-
80N.
The blower motor is wired on low speed for heating mode of the GMD2-60N and
medium low speed for heating mode of the GMD2-80N.
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
GMD2-60N furnace must fall within a range of 45
F to 75
F or 55
F to 85
F for the
GMD2-80N. 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 integrated furnace 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.
