GC9C80 Installation Manual
22
Refer to your furnace rating plate for the maximum ESP (ex-
ternal duct static) rating.
Total external static refers to everything external to the fur-
must all be considered when reading your total external
static pressure. The supply duct pressure must be read be-
tween the furnace and the cooling coil.
This reading is usually taken by removing the “A” shaped
reading at the test hole. Tape up the test hole after your test
is complete. The negative pressure must be read between
that can cause excessive temperature rise. This can cause
limit switch tripping and heat exchanger failure.
To determine total external duct static pressure, proceed as
follows:
1.
measure the static pressure of the return duct at the
inlet of the furnace. (Negative Pressure)
2. Measure the static pressure of the supply duct. (Positive
Pressure)
3.
Both readings may be taken simultaneously and read
directly on the manometer if so desired. If an air conditioner
furnace, the readings must also include theses components,
as shown in the following drawing.
4.
If the total external static pressure exceeds the maximum list-
ed on the furnace rating plate, check for closed dampers, reg-
isters, undersized and/or oversized poorly laid out duct work.
The temperature rise of the furnace must be within the tem-
perature rise range listed on the furnace rating plate.
1.
furnace.
2.
3. Set the room thermostat to the lowest possible setting.
4. Remove the burner compartment door.
This furnace is equipped with an ignition device
burner by hand.
5. Move the furnace gas valve manual con
position.
6.
7.
the safety instructions in the Safety Considerations on
minutes, move the furnace gas valve manual control to
the ON position.
8. Replace the burner compartment door.
9.
furnace.
10. Turn on the electrical power to the furnace.
11. Adjust the thermostat to a setting above room
temperature.
12. After the burners are lit, set the thermostat to desired
temperature.