6
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
GRH/P 029
O.D.S.
GAS REGULATOR
GRH/P 032
GRH/P028
Gas Valve
Oxygen Depletion System (O.D.S.)
The pilot burner is designed to produce a preci-
sion flame which will lift off of the pilot
thermocouple if the oxy-
gen content of the sur-
rounding air is too low.
The resulting cooling
of the pilot thermo-
Figure 6. Oxygen Depletion System
Control Valve
The control valve directs the flow of gas to the
pilot burner and the main burners. The con-
trol knob should be slightly depressed and
rotated to select the appropriate heat set-
ting, the “PILOT” setting or to turn the
heater off.
The control valve will maintain gas
flow to the main burner and the pilot
burner only if the thermocouple which
is mounted on the pilot burner is suffi-
ciently heated. The heated thermo-
couple provides a low level electric current to an
electromagnetic plunger in the control valve.
This low level electric current keeps the
plunger open allowing gas to flow to the
pilot and the main burner. If the pilot
flame is extinguished, or if the
pilot flame lifts off of the
thermocouple due to lack of
oxygen, the electric current to
the valve will be reduced and the plunger will
close, shutting off all gas flow to the heater.
Gas Regulator
The gas regulator is used to reduce the incoming
gas pressure to the appropri-
ate pressure for proper op-
eration of the heater. The
regulator pressure is preset
and cannot be adjusted.
NOTE: Propane heaters also require an exter-
nal regulator (11"-14" W.C.) be in-
stalled. The external regulator is not
supplied with the heater.
Figure 4. Control Valve
Figure 5. Gas Regulator
couple will cause the control valve to close,
shutting off all gas flow to the
heater. The oxygen deple-
tion system is required
on all models of vent-
free heaters covered
by this manual.
Pilot
Control
Valve
