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Temperature in house rises way above thermostat setting

HWGNY Member Posts: 2
Every so often, the temperature on the 2nd floor of our house stays at 68 F (20 C) all night, even though the overnight setting on both thermostats of our houses' two-zone system is 64 (18 C) degrees. This happens quite irregularly; on most nights, the temperature falls normally to the set level. I am quite puzzled.

This can happen when the outside temperature is below freezing, as tonight. It is now 4 hours after the night setting kicked in, the setting has definitely not been altered (pressing "present setting" shows 64), and there is this 4-degree F differential. Incidentally, the temperature is holding stable at a level above even the day setting, which is 67.

Any clues as to what is going on?


  • LionA29
    LionA29 Member Posts: 255
    Do you do any work on your heating system?
  • jacobsond
    jacobsond Member Posts: 85
    And you have verified that the heat is not shutting down in that zone.
    coming to you from warm and sunny ND
  • Is the thermometer accurate? If you were to set a constant temperature, with no setback, would it remain at the set point?
    Does your boiler make hot water as well as heat?--NBC
    HWGNY Member Posts: 2
    edited February 2017
    OK -- I have discovered that the setting on the thermostat downstairs was overridden, so that it was actually set to 70 degrees overnight...I'm guessing that the heat rose and warmed the upstairs, as well, without the thermostat ever actually triggering the heat upstairs.

    Result: very cold bedrooms, very warm hallway (where the thermostat is).

    Sorry -- I should have checked this first thing. Thanks for all the responses!