GPG14M User Mannual
6
A number of safety circuits are employed to ensure safe and proper
unit operation. These circuits serve to control any potential 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.
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 insucient condi-
tioned 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
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 ame. If there is an improper draw of
burner ames into the heat exchanger, the rollout limit will detect it
and shut o gas owing to the burners. Contact a qualied servicer
to check the unit before resetting this device.
NOTE: Ultra Low NOx models have sealed burner box and do
not have a rollout limit. Sealed burner boxes are equipped with
automatic reset blocked burner limit switch which will shut o the gas
supply when burner box temperature exceeds designed set point.
The limit will automatically reset when the burner box temperature
drops below designed set point. The control would enter a one hour
lockout if the limit exceeds maximum recovery time of 5 minutes or
if the limit has tripped three times in same heating call.
Rollout Protection
Rollout Protection on Burner Bracket
This gas/electric package unit includes components which are
designed to protect the compressor against abnormal operating
conditions.
NOTE: The operation of the indoor blower will not be aected by
any compressor protection devices.
If, during a call for cooling, the indoor fan runs and circulates room
temperature air while the compressor and outdoor fan do not operate:
1. Wait ve minutes, as a protection device may be holding the
compressor o.
2. Check the room thermostat to see if it is correctly set.
3. If the room thermostat is correctly set, call a qualied servicer
to determine if one of the compressor protection devices has
opened.
A short-cycle protector is built into the ignition control. Each time the
compressor is o for less than 3 minutes, the short-cycle protector
will delay compressor startup for up to 3 minutes. This protects the
compressor from improper operation.
On Dual Fuel units (GPD/APD), the short-cycle protector will delay
the compressor 5 minutes.
NOTE: These units are not designed to provide mechanical cool-
ing at outdoor temperatures below 50°F. If low ambient cooling is
needed, consult a qualied servicer.
The unit has an electronic ignition device which lights the burners
automatically. Never try to light the burners by hand. It also has an
induced draft blower to exhaust combustion products.