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Matthew
Matthew, HVAC Technician
Category: HVAC
Satisfied Customers: 2014
Experience:  14 years experience in the HVAC field of service, installation, Manual J & D calculations
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I have a white Rogers thermostat type number 1F80 261. This

Resolved Question:

I have a white Rogers thermostat type number 1F80 – 261. This is my problem the temperature is set at 68 the actual temperature in the room as shown on the thermostat is 62°. When I shift the thermostat from off the heat would the setting on Otto the heater cycles on and runs for five or 10 min. and then cycles off. In order for me to restart the heater I need to move the switch from heat to off wait a few minutes move it back to auto sometimes I have to do this several times before I can restart the heater. Please advise.
Submitted: 5 years ago.
Category: HVAC
Expert:  Matthew replied 5 years ago.

Matthew :

Hello, My name is XXXXX XXXXX I will do my best to help you today.

Matthew :

Your furnace is cutting off on high limit because of an airflow issue. When you reset the thermostat it resets the limit and lets it fire back up, but the limit is already close to tripping again so it doesn't take long to do it all over again.

Matthew :

The high limit senses the temperature inside the furnace's heat exchanger and if the air isn't being pushed out properly it will exceed this high limit temperature and the limit opens causing the burners to go off and the blower to continue running to push the built up air out. Once the heat exchanger is cooled to it's reset temperature it will allow the furnace to come back on or if you reset the thermostat or high voltage power it will reset this limit. Like I said though when you do this the temperature inside is already built up and the limit will trip again soon.

Matthew :

Things that cause this are a dirty filter, dirty evaporator coil underside, blocked return runs, blocked supply runs, malfunctioning blower motor that is not coming on and pushing air with the burners on, or simply a malfunctioning limit device or control board.

Matthew :

Most furnaces will give you a blink code on the LED of the control board telling you that it is cut off on a fualt

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