S-310 Checking Pressure Control; High Altitude Application (Usa); Checking For Delayed Ignition - Goodman GMES80 Series Service And Troubleshooting

SERVICING
S-310 CHECKING PRESSURE SWITCH
The pressure switch a safety device to prevent the combustion
cycle from occurring with inadequate venting caused by a
restricted or blocked vent pipe on the 80% and 90% furnaces.
1. Remove burner compartment door to gain access to
pressure switch(es).
2. Remove wires from the pressure switch(es) electrical
terminals.
3. Using a VOM check from common terminal to NC
(Normally Closed) - should read open.
If switch reads as above proceed to Step 4, otherwise replace
control.
4. Remove the pressure control hose from the control and
interconnect with an inclined manometer as shown in the
following figures.
ID Blower Pressure Switch
Negative Pressure Measurement
(80% Upflow Single-Stage Furnace Shown,
Counterflow Similar)
40
S-311 HIGH ALTITUDE APPLICATION (USA)
Check your furnace rating plate to determine its rated altitude
(either 4500 or 5500 ft). Do not attempt to increase the firing
rate by changing orifices or increasing the manifold pressure
below 4500/5500 feet. This can causepoor combustion and
equipment failure. High altitude installations above 4500/5500
feet may require both a pressure switch and an orifice change.
These changes are necessary to compensate for the natural
reduction in the density of both the gasfuel 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
conversions must be performed by a qualified installer, or
service agency.
In some areas the gas supplier may artificially derate the
gas in an effort to compensate for the effects of altitude. If
the gas is artificially derated the appropriate orfice size must
be determined based on the BTU/ft
gas and the altitude. Refer to the National Fuel Gas Code,
NFPA 54/ANSI Z223.1, and information provided by the gas
supplier to determine the proper orifice size.
S-312 CHECKING FOR DELAYED IGNITION
Delayed ignition is a delay in lighting a combustible mixture
of gas and air which has accumulated in the combustion
chamber.
Furnace design makes this extremely unlikely unless safety
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
S-307 CHECKING GAS PRESSURE).
2. Improper burner positioning - burners should be in locating
slots, level front to rear and left to right.
3. Carry over (lighter tube or cross lighter) obstructed - clean.
4. Main burner orifice(s) deformed, or out of alignment to
burner - replace.
content of the derated
3