GPD14 User's Manual

6
SAFETY CIRCUITS
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.
SECONDARY LIMIT
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 sen-
sor. This limit guards against overheating as a result of insuffi-
cient 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
ROLLOUT LIMIT
WARNING
THE 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
COMPRESSOR PROTECTION DEVICES
This gas/electric package unit includes components which are
designed to protect the compressor against abnormal operat-
ing conditions.
NOTE: The operation of the indoor blower will not be affected 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 five minutes, as a protection device may be holding the
compressor off.
2. Check the room thermostat to see if it is correctly set.
3. If the room thermostat is correctly set, call a qualified servicer
to determine if one of the compressor protection devices
has opened.
SHORT-CYCLE PROTECTOR
A short-cycle protector is built into the ignition control. Each time
the compressor is off 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
cooling at outdoor temperatures below 50°F. If low ambient
cooling is needed, consult a qualified servicer.
IGNITER
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 prod-
ucts.