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relief valve sizing

smc Member Posts: 18
installed a 500,000 btu input hot water boiler. Plate on boiler calls for minimum 600 lb/hr relief capacity. Do I use 970 per pound to convert to btu's?


    EBEBRATT-Ed Member Posts: 15,849
    edited October 2017
    Just make sure you are putting a hot water relief valve on the boiler and not a steam safety valve.

    The reason I ask is that steam safety valves may be rated in lb/hr but hot water relief valves should be rated in btu/hour.

    if this is a new boiler it should have come with the correct relief valve.

    Also, make sure the valve is rated for a pressure not to exceed the rating of the boiler (perferebley lower).

    make sure the btu rating of the valve is larger than the boiler rating

    If you have a non- ASME rated expansion tank your relief valve cannot exceed 30 psi
  • smc
    smc Member Posts: 18
    confused the tech rep at the relief valve manufacturer of the one we used, also confused boiler tech rep. everyone says go by btu but when stamped 600 lb/hr on boiler I have no way to argue with the state inspector. watts tech rep (not the brand we used) finally said use the 970=1lb. we originally used a 510,00 relief on 500,000 input. changed to larger one now