GAS water heater, I turn off the gas valve and water, but leave the thermostat at low level, didn’t turn it off. I will back the house in 10 days, Will this cause any issue?enter image description hereenter image description here

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    Is there any electrical connection at all? If this is a "traditional" gas heater with pilot, the thermostat can't do anything at all without the pilot on, so no problem. If it has some sort of electronic ignition then it is a different situation. If you are not sure, post the model # and/or a picture of the controls and we can probably figure it out. Commented Dec 20, 2018 at 4:41
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    Surely all gas water heaters are designed to not be damaged if the gas is shut off without turning the thermostat to off first. Commented Dec 20, 2018 at 8:33
  • @manassehkarz I don’t know what’s version, but my heater is more than 10 years old and I didn’t see a ignition button next to the gas valve.
    – Brian Z
    Commented Dec 20, 2018 at 12:38
  • Not in the house, so not able to check the version. Another question is, I didn’t drain the water, so when the temperature is fall and under the setting of thermostat, will it continuously try to ignite the gas to burn the water? If yes, will it cause some problem?
    – Brian Z
    Commented Dec 20, 2018 at 12:48
  • @Jim Stewart I turn the gas valve off, but.didn't turn the ball valve on the gas pipeline off, is this fine? I saw somone said turn off the gas valve doesn’t mean completely turn off the gas.
    – Brian Z
    Commented Dec 20, 2018 at 12:57

1 Answer 1


Assuming everything's in good working order, then no problem. Turning off the gas killed the pilot and stopped the water heater from doing anything by the thermocouple.

However, based on your comments you may have bigger problems than a few wasted dollars from leaving the water heater running. It seems you shut the heat off to the house as well when you left and are worried about the water heater possibly freezing.

The water heater would be the last thing to freeze in being such a big and thick column of water. But yes, it could freeze after all of your other plumbing.

You must winterize properly to avoid damage to everything or just turn things down so they only maintain easier lower temperatures.

  • I have left my furnace on at 51 f.
    – Brian Z
    Commented Dec 20, 2018 at 23:09
  • So, freezing is not my concern, but leave the gas pipeline on is my concern (I did turn off the gas valve). But, I think my heater should be fine as the pilot is off.
    – Brian Z
    Commented Dec 20, 2018 at 23:27
  • I saw there has something looks like ice inside of the tank, no ice outside of the tank. Is the tank frozen inside?@lggy
    – Brian Z
    Commented Dec 28, 2018 at 3:01
  • Yep, you got some freezing, thank you very much for the pictures. It's nothing major, thankfully, and the ice could only block the flow out to the fixtures. Start the heater and give the ice an hour or so to melt, you'll be just fine.
    – Iggy
    Commented Dec 28, 2018 at 14:34

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