On multiple occasions now, I have noticed odd things going on with my HVAC system, only to go to the thermostat and find that it has been set to heat! This happened once in the middle of summer, when it was 95+ degrees outside... I came home and the house was burning up! It happened again just last week during a cold snap. No kids in the house, and neither my wife nor I have adjusted the thermostat during the times when it was set to heat... so it's just changing itself. What could possibly be going on? I'm assuming it's a malfunction and I'm just going to replace it, but I wanted to check first.

Incidentally, I leave my pilot light off for my furnace except for November to March. Gotta save those few bucks. So, when the heat comes on, it's just running the system but not actually blowing hot air since the gas is turned off...

  • maybe a timer function set to turn your house into an oven? – ratchet freak Oct 7 '14 at 14:09
  • What is the make and model of the thermostat? Does it have a physical switch to change between heat/cool/off? – Tester101 Oct 7 '14 at 15:24
  • What is the make and model of the furnace? It's odd that the furnace would do anything, without sensing a flame. – Tester101 Oct 7 '14 at 15:26
  • I'll get the make/model when I get home... it does not have a physical switch, it has a button that cycles through the settings. I'm replacing it this afternoon anyway, but I wanted to make sure it didn't have something to do with the furnace rather than the thermostat. – John Chrysostom Oct 7 '14 at 15:32
  • If it was a physical switch, I would say it was a ghost. Since it's not, I'd say it's a bad thermostat, or an improperly set setting. – Tester101 Oct 7 '14 at 17:07

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