GM9S80 Service Manual

SERVICING
39
.



Check your furnace rating plate to determine its rated al-
titude (either 4500 or 5500 ft). Do not attempt to increase
   -
fold pressure below 4500/5500 feet. This can cause poor
combustion and equipment failure. High altitude installations
above 4500/5500 feet may require both a pressure switch
        
compensate for the natural reduction in the density of both
the gas fuel and the combustion air at higher altitude.
For installations above 4500/5500 feet, please refer to your
distributor for required kit(s). Contact the distributor for a
tabular listing of appropriate manufacturer’s kits for propane
gas and/or high altitude installations. The indicated kits must
be used to insure safe and proper furnace operation. All
    
service agency.
         
󰀨󰀨

be determined based on the BTU/ft
3
content of the derated
gas and the altitude. Refer to the National Fuel Gas Code,
NFPA 54/ANSI Z223.1, and information provided by the gas



of gas and air which has accumulated in the combustion
chamber.

controls have been by-passed or tampered with. Never by-
pass or alter furnace controls.
If delayed ignition should occur, the following should be
checked:
1. Improper gas pressure - Adjust to proper pressure
(See CHECKING GAS PRESSURE).
2. Improper burner positioning - burners should be in lo-
cating slots, level front to rear and left to right.
3. Carry over (lighter tube or cross lighter) obstructed -
clean.
4. 
burner - replace.


 Failure to earth ground the furnace, reversing the
neutral and hot wire connection to the line (polarity), or a
high resistance connection in the neutral line may cause the



-

The ground wire must run from the furnace all the way back

by disconnecting the electrical power and measuring resis-
tance between the neutral (white) connection and the burner

10 ohms.
The ignition control is a combination electronic and electro-

must be replaced.