From time to time my heater will suddenly start throwing out cold air the thermostat will go down 5-10 degrees lower than it's set at for several hrs. Then for no reason it will start giving out warm air again like it's supposed to. Sometimes it will even go 1-2 degrees higher than originally set before clicking off. It's done it a couple of times a month all this winter. Besides being cold I presume it's wasting energy money. This is the second year it's done it. But it doesn't do it in the summer with the cooling. I use electric for cooling gas for heating. Anyone have any ideas? My nephew has worked with heating/cooling units at work but never heard of anything like this.
Sounds to me like a fan limit switch sticking closed. That is the component responsible for running the fan until the remaining heat is removed from the heat exchanger. (to keep it from cracking) But, it only does what the thermostat tells it do do.... The heater not initializing and then running too long is the anticipator in the thermostat not set right or not working at all. That component is responsible for turning on the heat before it cools off too much and then telling the heat to shut off before it gets too hot,.... to even out the temperature swing. Your best bet would be to try to get your hands on an old analog thermostat. That may iron out the whole problem.
