I have a water heater that is 20 years old. When we turn up the water temp the pressure release value opens and drains water into the overflow pipe. The issue is this then overflows from the top of the pipe onto the floor and is only fixed by turning the water temp down. The water temp setting doesnt even have to be too high for this to happen. Time for a new water heater??

  • Is there an expansion tank installed? What are you setting the temperature to? Has the unit been off, or turned down low for an extended period?
    – Tester101
    Aug 4, 2015 at 20:07
  • No tank. It is set to low. Anything above medium it opens. And yes, it was off for like 9 months
    – Packy
    Aug 4, 2015 at 20:08
  • Is there a check valve on the main supply? Is this a recent purchase?
    – Tester101
    Aug 4, 2015 at 20:10
  • Not that I know. This thing is 20+ years old
    – Packy
    Aug 4, 2015 at 20:13
  • Sometimes during the sale of a house, there's a requirement that a check valve be installed. This is a great idea, as the valve helps prevent contamination of the water supply. However, the installation of an expansion tank is not always required, even though it is often required for the proper operation of the water heating system once a check valve is installed.
    – Tester101
    Aug 4, 2015 at 20:20

1 Answer 1


20 years old, it's almost certainly time for a new one unless it's of very unusual construction - like stainless steel.

If water:

overflows from the top of the pipe onto the floor

Then the overflow pipe is not correctly routed - it should go DIRECTLY down to the floor. I can see it going sideways in the picture on your other question. It also appears to be reduced in size, which is a code violation, and if it's positioned so that water is held (trapped) in it, that's a code violation.

enter image description here

Many hot water heaters need an expansion tank to avoid over-pressurizing the PRV when heating a slug of cold water when no water is being used. Most PRVs are rather bad about resealing when they have been "exercised" a bit. Both of these may play into your problem.

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