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backflow valve ?

dpenny
dpenny Member Posts: 12
edited March 17 in Gas Heating

Why does backflow preventor have an outlet?

What does it mean if it is dripping.

Is in a 12 yr old hydronic baseboard sys.

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Rinnai3b.jpg

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 17,415

    It means the backflow preventer needs replacement. You can probably get a rebuild kit for it if you think it is worth it.

  • Intplm.
    Intplm. Member Posts: 2,520

    As @EBEBRATT-Ed says above, absolutely rebuild the thing. If the money is about the same you can purchase the same one for direct replacement if you prefer.

  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,340

    "Why does backflow preventor have an outlet?"

    A check valve will stop backflow without venting, but it can become fouled and allow seepage back into the potable system.

    That Watts 9D is a step up from a check valve and will dump any water trying to get back.

    And then there's the RP device which you see at hospitals, irrigation systems and any highly toxic installations, protecting the fresh water system. San Francisco requires these on hydronic systems (overkill?) and they have to be inspected, tested and certified every year. There are others, but the RP device is the one you see most often.

    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • Intplm.
    Intplm. Member Posts: 2,520

    @Alan (California Radiant) Forbes You answered your own question in your above post, or did you already know that? That discharge port on back flow preventers are there as you say to dump water when back flow is sensed in the system.

    One of the biggest complaints is when such a device, or reduced pressure zone device (RPZ) is installed on a fire suppression system. The reason its a complaint, and a very legitimate one in my view, is because when the water spills out of the discharge it is not discharging onto a fire lessoning, or fully negating the fire suppression system. The water should be putting out the fire and not discharging on the floor.

    In many states the health department along with building departments require these in what can be categorized as high level hazard installation and low level installations.

    A high hazard would be the water supply to a boiler feed as boilers can be treated with chemicals potentially getting to the drinking water supply.

  • Jamie Hall
    Jamie Hall Member Posts: 25,756

    Someone complains if an RPZ or similar is discharging out of the vent? And this is a problem? May I humbly point out that the only time it will do that is if isn't functioning properly and needs servicing or replacement? Preferably yesterday morning?

    Don't complain about it. Fix it.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Intplm.
  • hot_rod
    hot_rod Member Posts: 24,713

    There are many different types of BFD, and there is a difference between backflow and back pressure condition.

    NFPA explains the different types.

    The issue with boiler water, is it a high hazard or not? Plain water, probably not, if someone adds ethylene , automotive , type antifreeze, cleaners, conditioners, etc, now you need a higher level BFD. Many boiler inspectors error on the higher hazard versions.

    Oddly enough the very best is sometimes the simplest, an air gap :)

    We had the City of Milwaukee backflow trainer/ inspector on a Coffee with Caleffi a few years back. Very interesting presentation.

    The BFD device that concerns them the most is a small simple device found on soft drink and coffee machines, and ASSE 1022 listed BFD. With Coke towers the concern is CO2 pushing into the city water supply. There are millions of these small in use across the country.

    https://www.nfpa.org/news-blogs-and-articles/blogs/2022/10/28/backflow-preventer-types

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream

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