To protect an unvented hot water tank on a central heating system should the pressure relief valve be installed on the inlet or the outlet pipework?

What is the best practice basically.

  • This may be a pressure relief valve, but most are temperature/pressure relief and these are always located on the outlet. I think my tankless water heater has a pressure relief valve and it is located on the outlet. Aug 8, 2018 at 11:35

1 Answer 1


In my area, temperature/pressure valves are required on all storage type domestic and production water tanks and must be installed in the top or near the top of the tank. Pressure relief valves that do not respond to temperature are required on all other heat producing boilers such as hot water heating and steam boilers. To answer your question, more information is needed about the system and the tanks actual use.

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