If your gas furnace keeps cycling on and then turning off within a minute or so, it might be the result of a dirty flame sensor. Most gas furnaces have a small sensor designed to shut off the ...

— J.B., Hornell. The problem may be with the flame sensor, according to heating contractor Dave Feldman. This is a safety device to check the presence of flame so that the furnace can operate.

In principle we can use a regular infrared diode or phototransistor to sense a flame. Certain thermocouples and thermopiles can also be used to sense heat or temperature as employed in most water ...

Here a readily available photo transistor 2N5777 (T1) works as the flame sensor. The 5V regulated dc supply for this circuit can be derived from a 12 V mains adaptor or a 9V rechargeable battery. In ...

Getting your furnace going during cold weather is a high priority and should be dealt with immediately, but it doesn’t ...