when furnace fails first start with thermostat

When a furnace stops heating there are many things a home owner can do to fix the problem before calling in a professional and paying lots of money

first thing you should check is your thermostat and make sure it is set properly


  • heat/cool/heat/off switch is set to heat
  • auto/on does not affect heat call -on fan will run all the time and change speeds with heat or cooling call -auto fan only runs on heat or cooling calls
  • temperature call must be higher then the room temperature where the thermostat is located (when house is cold, by adding heat near the thermostat it may cause the furnace not to come on due to that heat. the rest of the house will be cold
  • digital thermostats will use battery’s make sure they are above 1.5 volts. Do not use rechargeable battery’s, as they are designed for cameras and are only 1.2 volts.some digital thermostats do not require battery to run, because they are getting power from furnace on “C” terminal . Some any time “C” terminal is connected the battery’s are only good if you remove thermostat from wall for programming . Battery’s will leak if left for long time it is still recommended to replace battery’s every couple years. Battery’s should be tested yearly


  • similar to heating except heat/cool/off must be set to cool
  • temperature must be set below room temperature

Click here to see my Post “Next step after Thermostat”
Click here to see my Post “Cracked Heat Exchanger”
Click here to see my Post on protecting your home when on vacation “Alarm for Home”

Thank you for visiting my blog I would appreciate any feedback I can get, Please leave a comment on whether my information has helped you. I am always interested in more topic to write about, so feel free to leave a comment asking about anything related to HVAC-R(Heating, Ventilation ,air conditioning, refrigeration).

Thanks for reading my blog

9 thoughts on “when furnace fails first start with thermostat

  1. Arcelia 11/29/2012 at 10:28 pm Reply

    Your post, when furnace fails first start with thermostat furnace trouble shooting help, is really well written and insightful. Glad I found your website, warm regards from Arcelia!


    • jetstrem 12/10/2012 at 2:50 pm Reply

      Thanks for your comment about thermostat trouble shooting help. I like to see everyone figure out the simple problems first before paying big money on repairs.

  2. Maybell 12/18/2012 at 4:58 am Reply

    Great post, really enjoyed it!
    — Maybell


    • jetstrem 12/18/2012 at 8:56 am Reply

      Thanks for your comment with my post about thermostat checking tips. Lots of problems will be in thermostat and not a major problem, best if people look at the thermostat before calling a professional or suffering without heat.thermostat battery’s should be checked every fall and replaced if weak.

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