We have turned off one of our gas water heaters because we simply have low demand. What we wonder about is how to treat the mothballed heater? Should we leave the water in it? switch between water heaters monthly or at all? What problems with the water itself will occur if we do not use a water heater?

What is the best scheme to keep the unused heater in good shape so as to be a replacement should the other heater fail? Thanks for your help, E. Underwood

  • Are they installed in series or parallel? (Will water flow through the disabled unit?)
    – isherwood
    Jan 17 '19 at 15:46
  • They are independent
    – user95771
    Jan 17 '19 at 21:09

I would be 100% sure that the power is disconnected (or the gas supply and controls are turned off), then drain it completely. Water heaters should be drained annually anyway to purge sediment, so this won't hurt a thing.

Take precautions to be sure that power won't be reconnected until the heater is completely full of water to avoid damage to heating elements.

  • 1
    Since gas I would shut the gas off but I knew that's what you meant.+ drain and no gas since a pilot would waste gas and use some of the life being on pilot for a long time.
    – Ed Beal
    Feb 17 '19 at 1:20

A glass lined steel tank is protected by the anode. When you drain the tank, it will be 100% humidity and will hold around a gallon of water even when drained. The anode only works when the tank is full of water. Storing empty and damp is a bad idea.

A disconnected tank can be tipped over 45 degrees to get more water out. Drying the tank would require air flow through the tank for long time.

Better to store with water in it once wet or find a way to dry with an air pump.

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