Yesterday my heater was working as normal.

Today I replaced the filter in my Day & Night forced air heater. Later I bumped my thermostat when walking by it, but I'm not certain that this caused the problem.

My heater turned on and blew hot air. I turned it all the way down, but the fan kept blowing hot air (for about an hour). Eventually, I decided to throw a breaker to turn it off, hoping that turning it back on would reset. Unfortunatlely, when I turned it back on, the fan kept blowing cold air, whether I turn it all the way up or all the way down.

So I replaced the thermostat thinking I might have broken it... but have the same result.

There is no "fan" switch on my thermostat. I haven't opened up my heater yet to inspect it.

Any ideas?

Thanks!
Bruce.

Best guess is. When you turned off the power to the furnace while the burners where running. The heat had no where to go and tripped a limit. I can't tell you which one or where. If it is a downflow fornace, it's probably the one in the blower compartment.