I just replaced the safety valve on my water heater. The only immediately available replacement was an inch taller than the original. It is still in contact with the water. Is it safe?

This is the exact fit replacement part (it was not in stock locally): http://www.homedepot.com/p/Rheem-PROTECH-3-1-4-in-Standard-Shank-Water-Heater-Temperature-and-Pressure-Relief-Valve-SP12574/205651345

This is the part I bought (it is taller and the temperature rod is shorter): http://www.homedepot.com/p/Cash-Acme-3-4-in-Bronze-NCLX-5LX-Temperature-and-Pressure-Relief-Valve-with-2-1-2-in-Shank-MNPT-Inlet-x-FNPT-Outlet-23577-0150/203164748

Is this replacement part adequately safe or should I go ahead and order the exact fit?

  • @Mazura has given a good answer from the Wisconsin, USA code; are you in the USA? Dec 18, 2016 at 19:39
  • Yes I am in the US
    – Freiheit
    Dec 18, 2016 at 19:51
  • As long as the new sensing element is as long as the old one was, relative to where the threads are, it should be fine. Total height of the assembly is only a concern if it raises the discharge pipe above 6" off the floor.
    – Mazura
    Dec 18, 2016 at 19:51
  • Freihelt,I've noticed this on the new tanks with the T&P valve on the top. The temp probe only extends 2" (app) in the water. So that tells my the code or the manufacturers need to get their stuff together. I've gotten 6 different answers from the manufacturer and so called high priced plumbers.
    – Kent
    Feb 8, 2020 at 20:41

1 Answer 1


TPR valve shall extend into the heater tank and monitor the temperature in the top 6 inches of the heater. The discharge pipe shall terminate within 6 inches over the floor and not have any threads on the end, nor are there to be any valves in it.

  1. All pressurized storage-type water heaters and unfired hot water storage tanks shall be equipped with one or more combination temperature and pressure relief valves. The temperature steam rating of a combination temperature and pressure relief valve or valves shall equal or exceed the energy input rating in BTU per hour of the water heater. No shut off valve or other restricting device may be installed between the water heater or storage tank and the combination temperature and pressure relief valve.

  2. All pressurized non-storage type water heaters shall be provided with a pressure relief valve installed at the hot water outlet with no shut off valve between the heater and the relief valve.

3. Temperature and pressure relief valves shall be installed so that the sensing element of the valve extends into the heater tank and monitors the temperature in the top 6 inches of the heater or tank.

  1. Every relief valve which is designed to discharge water or steam shall be connected to a discharge pipe.

    5 (a) The discharge pipe and fittings shall be made of a material acceptable for water distribution piping in accordance with s.Comm 84.30 (4) (e) 1.

    5 (b) The discharge pipe and fittings shall have a diameter not less than the diameter of the relief valve outlet.

    5 (c) The discharge pipe may not be trapped.

    5 (d) No valve may be installed in the discharge pipe.

5 (e) The discharge pipe shall be installed to drain by gravity flow to a floor served by a floor drain or to a receptor in accordance with s. Comm 82.33 (8). The outlet of the discharge pipe shall terminate within 6 inches over the floor or receptor, but not less than a distance equal to twice the diameter of the outlet pipe. The discharge pipe may not be threaded.


  • That is within the top 6". So if the temperature element being 3.5" or 2.5" is fine as long as it is in the water and not more than 6" in the water
    – Freiheit
    Dec 18, 2016 at 19:52
  • 1
    @Freiheit - Note, it states "in the top 6 inches" not 'within'. As in, "monitor the temperature [throughout] the top 6 inches". To determine if it's safe, we'd need the model number of your tank and the part that you used. Then again, some TPR valves go on the side, about 6" down from the top, so the important part is probably getting all the way down 6" - far enough down so that it can be in the convection current swirl.
    – Mazura
    Dec 18, 2016 at 20:37
  • 1
    It's probably fine is not advice I like to give concerning safety equipment. But anything's better than capping it or relying on an old one that might not function properly.
    – Mazura
    Dec 18, 2016 at 21:02
  • 1
    I've updated my question with the exact match replacement and the one I bought. Even the original part would not have had its temperature rod extending down 6" into the water heater.
    – Freiheit
    Dec 19, 2016 at 14:22

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.