Fedders F80A dimensions Sequence Of Operation, Variations, Warm Air Furnace

WARNING

ALWAYS DISCONNECT THE ELECTRICAL SUPPLY TO THE FURNACE BEFORE REMOVING THE BURNER COMPARTMENT ACCESS DOOR.

CAUTION

THE FURNACE SHOULD BE OPERATED WITH ALL PANELS IN PLACE. NEVER OPERATE THE FURNACE WITH THE BLOWER DOOR REMOVED EXCEPT FOR SERVICE PURPOSES.

The furnace achieves its mid-efficiency in two general areas. First, there is no wasteful standing pilot. The furnace consumes no gas in between cycles. Secondly, the furnace is designed to allow very small amounts of excess air in the combustion process. Older furnaces had heat exchangers that were commonly 40% larger than necessary for complete combustion. While this prevented the creation of carbon monoxide, the heated excess air was expelled up the chimney where it could not benefit the interior of the home. Special safety controls now prevent the formation of carbon monoxide.

IMPORTANT

Your furnace should be cleaned and inspected annually by a trained and qualified service technician.

Your service technician has the knowledge and test equipment to determine the condition of your furnace.

WARNING

THE EXHAUST GASES FROM THIS FURNACE CONTAIN CHEMICALS, WHICH ON SOME OCCASIONS MAY INCLUDE CARBON MONOXIDE (CO). CARBON MONOXIDE IS AN ODORLESS, TASTELESS, CLEAR COLORLESS GAS, WHICH IS HIGHLY TOXIC. EVEN LOW CONCENTRATIONS ARE SUSPECTED OF CAUSING BIRTH DEFECTS AND OTHER REPRODUCTIVE HARM.

UL AND CUL RECOGNIZED CO DETECTORS ARE RECOMMENDED FOR ALL BUILDINGS EQUIPPED WITH FOSSIL FUEL BURNING APPLIANCES. ALL CO DETECTORS SHOULD BE INSTALLED IN ACCORDANCE WITH THEIR MANUFACTURER’S INSTRUCTIONS AND APPLICABLE LOCAL BUILDING CODES.

WARM AIR FURNACE

SEQUENCE OF OPERATION

1.Thermostat, responding to cool room, calls for heat.

2.Combustion air blower begins.

3.After 15 second prepurge, hot surface igniter warms up.

4.After approximately 5 seconds, the gas valve will open, and the burners ignite.

5.Thirty seconds after the burners ignite and flame sense is proven, the main blower starts on the heating speed.

6.System remains in this state until the room air temperature rises causing the thermostat to terminate its call for heat.

7.The gas valve shuts off; the burners extinguish.

8.After brief postpurge period, (5 seconds), the combustion air fan stops. The main blower continues to run. Elapsed time ranges from 60 seconds to 180 seconds, depending on the manufacturer’s requirement.

9.The furnace remains idle until the next call for heat.

VARIATIONS

If your system includes air conditioning, your thermostat (supplied by the installer) will likely have two switches. The first switch is the system switch. The switch settings usually include HEAT, COOL, and OFF. Some thermostats have system switches which include HEAT, COOL, AUTO, and OFF. The system switch must be in the HEAT or AUTO position for the furnace to run.

The second switch is the fan switch. It usually has settings of ON and AUTO. The fan switch may be in either position when using the furnace. If the fan switch is set to ON, the main blower will run continuously, and the blower delays mentioned in the sequence of operation points 5 and 9 will be ignored.

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