18
V E N T - F R E E G A S H E A T E R S E R V I C E M A N U A L
Problem
Main burner does not light (pilot stays lit)
Possible Causes
1.
Low inlet gas pressure
2.
Burner orifice is clogged
3.
Burner orifice is not correct
Procedures
1.
Be sure that the supply pressure and line
size to the heater is adequate. Refer to
“SPECIFICATIONS” on page 13 for the
model you are servicing. If the supply line
is the correct size and the supply pres-
sure is low, contact your local gas com-
pany or LP supplier.
Propane (LP) Models Only:
A. Be sure tank is not empty or nearly
empty.
B. Be sure tank is not frozen due to high
usage rates on a small propane cylin-
der. If many appliances or heating
devices are being run off the same
tank, evaporation rates can cause the
remaining liquid to cool and create
GRH/P 031
Burner Orifice
frost or ice on the outside of the tank.
The ice acts as an insulator and can
reduce the evaporation rate and the
pressure to your heater. If an im-
proper tank size is causing a low
supply pressure to the heater, con-
tact the local LP gas supplier for proper
tank sizing.
2.
Check the burner orifices to be sure that
they are not clogged. Remove the
orifice(s) and examine for dirt or particles
which would restrict the flow of gas. DO
NOT attempt to clean the orifice(s) with a
wire. Blow out the orifice(s) or gently
clean. Replace the orifice(s) if neces-
sary.
3.
Check the burner orifice size. Refer to
the proper drill size in
“SPECIFICA-
TIONS” on page 13 for the model you are
servicing. If an orifice is not the correct
size, it should be replaced.
Problem
Delayed ignition of main burner
Possible Cause
1.
Low pressure to one or more burner
plaques.
Figure 22. Burner Orifice
Procedure
1.
Check for the cause of low pressure by
following procedure number 3 under
“Problem: Gas odor” at the bottom of
page 19.
Burner Orifice (Injector)
Washer
Injector Holder
