Monthly Archives: December 2020

Trane XR80 furnace

When we came back from our ski trip, our heater broke! I have to get it fixed!!

First of all, our HVAC is Trane XR80, I found  the simple manual of my xr80.

I found a few good videos instruction, they are all good suggestions. And, my friends told me some other tricks also.

Here is a good step by step instruction
Fix the flame sensor
A furnace not blowing hot air
Here are the possible false code
The thermostat shall get correct voltage, which is around 24 - 27 volt.

I went a long way and found out the possible correct procedures.

  • We need to check whether the electricity comes through well into the thermostat. Following this video to make sure correct voltage is read.
  • Next, go the furnace. Before opening it up, there could be error indicators codes. It is very helpful to diagnose.
  • Mine was "normal, no heat calling". I checked those low voltage measure, I got the same reading as those from the thermostat.
  • I should have known that it was the thermostat's problem, as NO signal is sent to the board.
  • If correct, those reading should be "zero" volt. I missed it badly.
  • Of course, if I passed this step, I need to check the ignition, flame sensor etc.
  • This should be the next episode in case I encounter any error in the future. Fingers crossed.
  • In my case, I am lucky (and unlucky) that it was a bad thermostat. Simply replacing the thermostat solves the problem.

    One more note is that the thermostat serves both “gas furnace” and “heat pump”. One needs to be careful when setting it up.