Section 3 - General Operation And Component Descriptions; General Operation; Burner Assembly; Ignition System - Desa CERAMIC PLAQUE Service Manual

V E N T - F R E E
GENERAL OPERATION AND COMPONENT DESCRIPTIONS
S E C T I O N
3

General Operation

NOTE: See Owner's Manual for operating
procedure.
The heater is operated by the control knob
located on the top of the heater. Be sure that the
service supply valve is open and that the manual
shut-off valve (Figure 8, page 9) is fully open.
Depressing the control knob and turning it to the
"PILOT" position will direct gas to the pilot and
provide a spark to light the pilot. The control
knob must be held down (at least 10 seconds)
until the thermocouple is heated enough to hold
the valve open. Once the pilot flame is
established, the control knob can be released
and turned to any of the operating position
settings. The control knob can also be left in the

Burner Assembly

The burner assembly is constructed of a plated
steel burner case with ceramic plaques ce-
mented into the face. A metal frame assures
uniform spacing between the plaques. The gas
orifices are mounted at the bottom of the air/gas
inlet tubes. The air/gas mixture is distributed to

Ignition System

The ignitor assembly utilizes a piezo electric
ignition system. The spark gen-
erator is built into the con-
trol valve and will pro-
vide a spark to the pi-
lot when the control
knob is fully de-
pressed and turned
G A S H E A T E R
"PILOT" position so that the heater is ready to
use.
Turning the control knob operates the control
valve and directs the flow of gas to the pilot and
the burner plaques. The gas is mixed with air
and is injected into the burner chambers through
tubes in the bottom of the burner. The air/gas
mixture burns on the surface of the ceramic
burner plaques, causing the ceramic plaques to
glow with a radiant orange color. With proper
care and servicing, the heater should give many
years of satisfactory use to the customer. Be
sure to inspect and service the heater at least
annually.
the plaques through the steel burner chambers
and through the small holes in the ceramic
plaques. The air/gas mixture burns near the
surface of the ceramic plaques, resulting in the
production of both radiant and convected heat.
from the "OFF" position to the "PILOT" position.
The resulting high voltage spark ignites the gas
Pilot
Control
Valve
IGNITION SYSTEM
Figure 3. Ignition System
S E R V I C E M A N U A L
at the pilot tube. The pilot flame will
in turn light the main burners
when the control knob is
rotated to the desired
heat setting.
GRH/P027
5