How do i get my furnace to work

Question

The problem that i have is my furnace will turn on and run but when it is time for it to kick off it kicks off and right back on again ,so why when it shuts off it does not stay of, It just goes on and off

Answer 1

Sound like a thermostat issue.

Answer 2

When it kicks back on, is it just the fan or is it the burners as well?

If the burners are coming back on, then it is most likely a thermostat issue. If just the fan is coming back on, it might be a furnace control or air flow issue.

On older furnaces, the fan is controlled by a temeperature switch. On a call for heat, the burners come on 1st allowing the heat exchanger to warm up. At a preset temperature, the fan control starts the fan. When your thermostat is satisfied, it turns off the burners and the fan continues to run to cool off the heat exchanger. If you have an air flow problem, the amount of air crossing the heat exchanger may not be high enough to cool the furnace down enough to keep the fan switch from restarting the fan. Also, the fan switch itself may have weakend and is causing what you are experiencing.

Answer 3

The furnace only does what it's told to do by the thermostat.  They're cheap, replace it

Answer 4

It sounds as if you have an older mercury bulb thermostat. If you remove the front cover of the tstat, you should see the mercury filled bulb. DO NOT TOUCH THE BULB!!! Mercury is hazardous. What would be happening is that the mercury switches over in the bulb and removes the pressure on the contacts in the tstat thus turning the system off, and then it is quickly switching back in the bulb thus creating the contacts and turning it on. This a common problem with older tstats.

Simply call your HVAC company and they should be able to install a new one. Or if you feel handy then you can purchase one at yourlocal home improvement store and install yourself. However, I always caution homeowners installing their own thermostats because they can cause other problems within the system if they install it incorrectly.

Good luck. For more information on thermostats - common problems, repairs, digital tstats, programmable thermostats,etc. go to www.howellsac.com