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RELIEF VALVE

DAVE LANDY
DAVE LANDY Member Posts: 3
in THE MAIN WALL
Why does the relief valve on a 650mbtuh water heater, (125PSI) have a BTU rating on the tag claiming in excess of 2.2 MILLION BTUh. Can anyone explain what this is based on? Thanks for any help.

Comments

  • Art Pittaway
    Art Pittaway Member Posts: 230
    The next one smaller

    was probably to small for the 650mbtuh heater you have. Relief valves come in "standard sizes" (with exceptions) and the shelf item that fits and covers the load load is what gets installed.
  • DAVE LANDY
    DAVE LANDY Member Posts: 3
    LOAD LOAD

    THANKS FOR NOT GETTING TOO TECHNICAL ART, BUT I WAS LOOKING FOR MAYBE A LITTLE MORE DETAIL.
  • Unknown
    Unknown Member
    here you go.

    http://www.conbraco.com/products/safety/indexsaf.html

    Look at the capacities of the 10-600 in 125 PSI

    Notice that 3/4" is the smallest size offered. It passes over 2 1/2 million BTUHs

    1" passes almost twice that amount.

    Art's right.

    Noel
  • Art Pittaway
    Art Pittaway Member Posts: 230
    Sorry,

    didn't mean to dumb down the reply. All levels of questions come up in this forum. The size depends on mainly burner input plus a "safty factor" depending on the code authority. BTUH X 1.5 (or whatever multiplier is required) or 500,000 load = 750,000 relief. Next is pressure set point, it is determined by the system. A residential water boiler will have a 12psi boiler running pressure and a boiler max. pressure of 50 psi, so usually the R/V is set at 30 psi. Ask your local plumbing code official what they recommend for your situation, he should be able to tell you off the top of his head. Go to Google.com and type in "relief valves" (with quotes) and find 'Conbreco manufacturing', they make lots of different relief valves. The site has some great info. Also, relief valves fall into many catagories, steam, water pressure, pressure & temperature and specials, etc. When you start to dig into the field, it's huge, and specialized. There are two companies in Chicago that only set (ASME Certified $$$) and sell custom relief valves to industry. Think about a typical house, one on the waterheater, and then think about an oil refinery or processing plant, hundreds of them, all sizes and shapes. I hope this little bit of detail helps.
  • DAVE LANDY
    DAVE LANDY Member Posts: 3
    relief valve

    Thank you Art, I knew there was a reason or formula, and now that you begin to open up that particular can or earthworms, I probably have a lot of other things I need to learn before I can do relief valve specs in my head. By the way, I am a countersales guy at Johnstone Supply #114
    Depew, NY. So I do have some questions asked of me by the customers that I need to find help with on (rare) occasion. Thanks again
  • Art Pittaway
    Art Pittaway Member Posts: 230
    Ahhh, now I know the market,

    your in. Johnstone has several companies that supply R/V's to them. ITT Industries Bell & Gossett, Taco, and Watts have the shelf item hydronic R/V's, you probably carry 3/4" thru 1 1/2" in brass and 2" + in Iron for your boiler replacements. In there catalogs you will see each has a chart that shows the range of pressure X size = output. For steam you may have ITT Hoffman, Spirax-Sarco, and Conbreco, the steam valves are sized in a similar way. If you really want to learn about this stuff, see if you can talk the boss into sending you to classes at some of these manufacturers. All of them have excellent topics from basic to advanced, system design or equipment service.
    Best wishes and glad I could help.
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