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    Which T&P Valve? (2 Posts)

  • Javelin Javelin @ 10:19 AM
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    Which T&P Valve?

    Heating Gurus,

    I have a Triangle Tube Prestige 250 boiler hooked up to a Smart 40 Indirect Hot water heater. Which T&P relief valve am I supposed to use? The manual seems to have two suggestions - one based on tank size, the other on BTU - but they differ:


    Determine T&P relief valve size by the follow- ing specifications, unless they conflict with local codes:
    - TR 20/30/36/45 - SMART 20/30/40/50: 3/4”NPT with an AGA Rating of 100,000 BTU/hr. (Watts 100XL-8 or equivalent).
    - TR 60/80/100/120 - SMART 60/80/100: 3/4”NPT with an AGA Rating of 200,000 BTU/hr. (Watts 40XL-8 or equivalent).


    Also, the Watts 100XL-8 is about $14 from PEX supply while the Watts 40XL-8 is about $130.. Why is there such a difference in price? Something I'm missing?

  • Neither one

    Here in California, you have to use a relief valves rated higher than the input rating of the boiler.

    Look at this chart (over 200,000 BTU) for correct sizing:

    As far as the higher price, it's probably related to their insurance costs and not the manufacturing costs.
    Often wrong, never in doubt.
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