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Should a backflow prevention device be installed to prevent water from the boiler from flowing into

FHills Member Posts: 20
Should a backflow prevention device be installed to prevent water from the boiler from flowing into the cold water supply? While installing the hot water heater replacement and repiping the cold water input feed into the boiler, my plumber noted that I did not have a backflow prevention device to prevent "contaminated water" from the boiler from backflowing into the tap water.  He says it's required by law in New York City where I live.  I checked online and there is such a requirement for large-scale dwellings but not yet for single-family residences like mine.  <a href="  ">  </a> Under my old arrangement where the hotwater heater fed the boiler, any backflow from the boiler would have to flow through the hot water heater tank before it could reach the cold water line.  Now, any backflow would have a more direct route to the cold water supply.  Is one necessary and/or good to have?  Should I have it installed above the auto water feeder on the cold water line?

Once again, thank you.


  • Joe V_2
    Joe V_2 Member Posts: 234
    edited April 2014
    I put one one mine

    and I also installed them on my branches to hose spigots. Dont know if it is code or not.

    My feeling is , that vertical pipe with water is a deadleg. Water in any deadleg becomes stagnant sitting there waiting for me to open a valve. Over time, microbes can grow and at night when the water in all the pipes is static, those microbes can float out of the dead leg and into my next glass of water. I am sometimes a victim of my own imagination, but I sleep well at night.
  • Fred
    Fred Member Posts: 8,518
    edited April 2014
    Me Too

    I have one on my boiler feed as well. I'm not as methodical as Joe V. I just figure on the occasions I might add some type of chemical to my boiler, I'd rather not have a cocktail in my morning glass of water :)
  • Kakashi
    Kakashi Member Posts: 88

    Have you ever seen/smelled/tasted the water from your boiler? When I was a rookie the senior tech told a trick on how to get water out of an expansion tank..........

    It is a law, in my area on new installs it is. Use common sense tho, the odds of it ever blowing are slim if you have city water. CYA :)
  • Bob Harper
    Bob Harper Member Posts: 868

    Backflow prevention is required by the International Codes and the EPA. If the fire dept. catches a local fire hydrant, it can suck boiler water not only into the home but back into the neighborhood, too. That's why the house itself should have backflow prevention, too.
  • heatpro02920
    heatpro02920 Member Posts: 991
    are we talking steam or fhw

    If I use an auto feed I put a check valve after the feeder, if it is a manual ball valve feed I don't install anything between or before..
  • FHills
    FHills Member Posts: 20
    A backflow preventer with more than 0.25% lead

    Thank you all for your insights.  My water does not taste like it contains anything from the boiler, but I went ahead and had a backflow preventer (Watts 1/2 BBFP).  See pictures.  But after the plumbing left, I noticed on the box a label that says the device contains more than 0.25% lead and:  "It is illegal to use this product in any plumbing system providing water for human consumption . . . everywhere in the United States after 2013."  The cold water flowing through this device is going into the boiler, and won't be used for human consumption, but the device is still part of a system that is providing potable water to the home.
  • Fred
    Fred Member Posts: 8,518
    All new ones are lead free

    The new brass plumbing fittings are now lead free. This is probably New, old Stock the plumber had on hand. Depending on when your house was plumbed/re-plumbed, most of the solder used on all the joints, not to mention any brass fittings and/or fixtures have lead in them. This install is not going to affect your water quality. 
  • FHills
    FHills Member Posts: 20
    I see, Pb in my water supply

    Thank you.  My house is old, so I guess I will have to continue using a water filter to deal with the lead.  My plumber is an old man from Genoa.  I joke with him that Italians are good at plumbing because they've been doing it since Roman times.  The Romans also used a lot of lead in their piping.  But circa 2014 CE, lead has been banished from plumbing.  Civilization has advanced. 
  • lza
    lza Member Posts: 40


    I could be wrong since I'm a fitter not a plumber, but it is now illegal to use anything other than lead-free products in your domestic water system.  He could face stiff penalties if it is inspected--and in most places backflows need to be certified annually. 
  • JOutterbridge
    JOutterbridge Member Posts: 11
    > @heatpro02920 said:
    > are we talking steam or fhw
    > If I use an auto feed I put a check valve after the feeder, if it is a manual ball valve feed I don't install anything between or before..

    Any reason why putting the check valve after the auto feed? I always see it before the fill even if their is a manual bypass or shut off avaliable.
  • hot_rod
    hot_rod Member Posts: 14,797
    Containment and isolation are the options for BFDs. Public water is supplied to you as potable. Once it enters a building it becomes not potable as far as the city is concerned, they don’t want it back😏. Most water providers require BFD on the supply to buildings. Additionally a building may also require individual BFDs on equipment inside the building to prevent contaminating your building water supply, even if it is prevented from going back to the provider.

    More and more AHJs want high hazard testable BFDs to assure the public system is protected at every connection

    RPZ type BFDs should be tested when installed, repaired and yearly, many jurisdictions record that data.

    There is a wide variety of devices depending on the application, fire protection, lawn sprinklers, boilers, hose bibs, espresso machines all require different listed BFDs

    We will have an expert on this subject Thursday Coffee with Caleffi webinar, noon central, to help wade through all the requirements

    codes may dictate devices, local AHJs can also require additional devices, most areas are toughening up requirements after Flint.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Erin Holohan Haskell
    Erin Holohan Haskell Member, Moderator, Administrator Posts: 1,599
    Thursday, Dec 13, Coffee with Caleffi: Backflow Preventers and How They are Applied
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