I have a digital thermostat and my furnace seems to stay on for only 2 minutes at a time. It does this approximately every 10 min. The programmed cycle rate is 5/hr, so starting up every 10 min makes sense.

If the programmed temp is 72 F and the room temp is around 72 F, it will start up as usual, but only stay on for 2 minutes then shut off. The fan also works.

If I override the programmed temperature to 77 F, the furnace will stay on until the desired temperature is reached.

Is it normal for a furnace to start up and run for only 2 minutes if the programmed temp is close to the room temp?

Thanks.

letmetellu

Is it possible that the air from one of your openings, that puts the heat into the room, could be blowing right on to the thermostat.

kornholio

The thermostat is not near any vents. Can someone tell me what the cycle rate setting for +/- 0.5 degrees means? Does it mean that the furnace starts up when the room temp is +/- 0.5 degrees from the programmed temp?