In fact the problems that affect gas furnaces typically involve the furnace s thermocouple the pilot light or some component of the electrical system.
Furnace thermal coupler.
If the pilot lights but won t stay lit the thermocouple is probably bad.
If it accumulates soot it can give off a faulty reading and shut off the furnace.
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Most gas furnaces use either a flame sensor or a thermocouple often referred to as a thermal coupler both are safety devices that sense the presence of a flame and control the flow of gas to the appliance accordingly.
If no flame is present the sensor stops or prevents the flow of gas from the gas valve thus preventing the dangerous situation of gas flowing into the appliance when there.
The thermocouple is a safety device located by the pilot light on your furnace.
This device generates a small electric signal to keep the gas valve open when the pilot is on.
Fortunately cleaning a thermocouple is a repair most handy homeowners can do themselves.
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