Our natural gas furnace kicks on and off too often. Sometimes fires up again 10 seconds after its shut off. I installed a new Honeywell thermostat but still does it. Is there something else that could be causing it? Other than the house was built in 1910 and is just draughty. Last month's gas bill was $127. Thanks ahead for any replies.

Try cleaning the heat sensor with a $ dollar bill. Very simple fix. Do not use anything that is really abrasive. The sensor is a six inch rod with a single wire to it. It is held by a single screw into the igniters. Very simple, just rub the $ bill over the surface of the sensor rod to clean its surface. The dollar bill (a five or one ) should be a newer bill. Not an old wrinkly one.

First off unless you are okay with messing with your own stuff. Call in a furnace guy.

I have a new furnace now only 2 years old. But when my old furnace did what you described. It was low batteries in the thermostat. Of course you said you replaced the thermostat.
When my son's furnace did what you described. First thing I told him was check his batteries in thermostat. Wasn't that. So little research on his furnace and I cleaned his flame sensor. That cured the problem and he was fine that winter. Next heating season same thing so I cleaned whole furnace and the sensor. Didn't work. So I replaced the sensor. Still didn't work. But wait doppy us. Cleaned all that stuff but hadn't changed the filter. It didn't look that bad. But there is also an air flow sensor on his furnace. New filter and ran like it was supposed to.

Mac

Hmm. I will try that!

Check the filter. Had the exact same issue when we were brand new homeowners, where the furnace would kick on and immediately kick off, over and over. Called the HVAC guy, and he found the furnace filter plugged solid.

filter, flame sensor dirty, high temp sensor thingy, does it flash a code when it messes up?

I changed the filter and cleaned both the thermocoupler and the heat sensor. I think. Still working so I'll monitor it and see if anything changes.

If it a newer furnace,,,,, it should have a little light on the main board that will flash.
The flash time and amount will be the code for diagnostic