Combustion Problems; Backfiring During Operation; Smoke Or Unwanted Odors; Gas Odor - Desa CERAMIC PLAQUE Service Manual

V E N T - F R E E

Combustion Problems

Problem

Backfiring during operation

Possible Causes
1. Burner damaged
2. Low pressure to one or more burner
plaques
Problem

Smoke or unwanted odors

Possible Causes
1. Oil or residue from manufacturing proc-
esses
2. Household chemicals
Procedures
1. If oils or residues from manufacturing
processes are present in the heater, the
problem will usually be eliminated after a
Problem

Gas odor

Possible Causes
1. Gas leak
2. Defective control valve
3. Dirt or particles clogging gas line
!
WARNING: If you smell gas:
• Shut off gas supply.
WARNING ICON G 001
• Do not try to light any appliance.
• Do not touch any electrical switch; do
not use any phone in your building.
• Immediately call your gas supplier from
a neighbor's phone. Follow the gas
supplier's instructions.
• If you cannot reach your gas supplier,
call the fire department.
Procedures
1. Check all heater and gas supply connec-
tions for leaks. See procedures under
"Testing Gas Supply Line Connections"
and "Testing Heater Gas Connections"
on page 11 of this service manual.
2. If all gas connections inside and outside
of the heater have been checked and
found to be free of leaks, check for a
defective control valve. Visually examine
the surface of the control valve to be sure
that it is not cracked, dented or damaged.
A small mirror and flashlight may be nec-
essary to examine the rear of the valve.
Check to be sure that the valve is mounted
securely in a vertical position, and that
G A S H E A T E R
Procedure
1.
2
2.
3.
S E R V I C E M A N U A L
Inspect the ceramic burner plaques to
see if the plaques are cracked or badly
chipped. If a burner plaque is cracked or
broken, replace the burner.
Check for low pressure to the burner by
following procedure number 3 under
"Problem: Gas odor" (bottom of page).
few hours of operation. If odors persist,
remove the front panel and examine the
inside of the heater cabinet for oil or
foreign material.
Some household chemicals, such as
paint, hair spray or glues can produce
unwanted odors when the heater is oper-
ating. Ventilate the room and advise the
user to discontinue using such products
while the heater is operating.
the control knob can be turned to all
positions. If any defect is found, replace
the control valve. Be sure to test all gas
connections for leaks after replacing the
control valve.
Low pressure to one or more burner
plaques can result in improper combus-
tion and gas odor. Check burner opera-
tion at the "HIGH" setting to see if all
plaques have the same uniform color.
A. If one plaque is glowing less than the
others, dirt or particles may be clog-
ging the line between the valve and
the burner, or the burner pipe may be
blocked by spider webs or other ob-
structions. Turn off gas to the heater
at the manual shut-off valve below
the heater. Remove the appropriate
gas line(s) to the burner and clean
foreign matter from the tubing. Check
the burner orifices and clean if neces-
sary.
B. If all plaques do not develop a full
radiance, check manifold pressure at
the 1/8" NPT tap located next to the
control valve. See "SPECIFICA-
TIONS" on page 13 for the model of
heater you are servicing. If manifold
pressure is low, check inlet (supply)
pressure to the heater. If the inlet
supply pressure is correct, clean the
inlet tube between the regulator and
valve. Replace the regulator and valve
if necessary.
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