5
Gas Valve
On/Off
Selector
Switch
INLET
OUTLET
White-Rodgers Model 36G22
Inlet
Pressure Boss
Low
Regulator Adjust
High Regulator
Adjust
Regulator
Vent
Outlet
Pressure Boss
White-Rodgers Model 36G54
Gas Valve On/Off
Selector Switch
Inlet
Pressure
Tap
Pressure Regulator
(under cap screw)
Outlet
Pressure
Tap
Honeywell Model VR8215 (Single-Stage)
S
AFETY
C
IRCUITS
A number of safety circuits are employed to ensure safe and
proper unit operation. These circuits serve to control any poten-
tial safety hazards and, as inputs in the monitoring and diagnosis
of abnormal operation.
WARNING
I
F THE SECONDARY LIMIT CONTROL SHOULD OPEN, THE REASON MUST BE
DETERMINED BEFORE THE CONTROL RESETS.
T
HE ELECTRICAL POWER
MUST BE DISCONNECTED BEFORE ANY PANEL IS REMOVED OR MAIN-
TENANCE IS PERFORMED.
S
ECONDARY
L
IMIT
The secondary limit control is located on the blower housing and
monitors blower compartment temperatures. It is a normally
closed (electrically), automatic reset, temperature activated
sensor. This limit guards against overheating as a result of
insufficient conditioned air passing over the heat exchanger. It
deenergizes the gas valve if the blower fails.
NOTE
: If the power to the unit is interrupted during the heating
cycle, it may cause the secondary limit to trip. Once the blower
compartment temperature drops below the limit reset
temperature, the limit will automatically reset.
Secondary
Control Limit
Back of Unit
Secondary Limit Control
R
OLLOUT
L
IMIT
WARNING
T
HE CAUSE OF THE ROLLOUT PROTECTION DEVICE OPENING MUST BE INVEST-
IGATED BY A QUALIFIED SERVICER BEFORE ANY ATTEMPT IS MADE TO RESET
THE ROLLOUT PROTECTION DEVICE AND TURN THE UNIT BACK ON.
T
HE
ELECTRICAL POWER MUST BE DISCONNECTED BEFORE EITHER FRONT PANEL
IS REMOVED.
The rollout limit is a normally-closed (electrically), manual-
reset, temperature-activated sensor. It is mounted on the burner
bracket and monitors the burner flame. If there is an improper
draw of burner flames into the heat exchanger, the rollout limit
will detect it and shut off gas flowing to the burners. Contact a
qualified servicer to check the unit before resetting this device.
Rollout Protection
Rollout Protection on Burner Bracket
