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whats a back flow preventer

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chris_93
chris_93 Member Posts: 84
I always thought taco feed valves have a built in backflow device, to prevent pressure loss on the system, should you lose water pressure. This is tacos link for their feed valves. Seems repetitative.
http://taco-hvac.com/en/products/Boiler%20Feed%20Valves/products.html?current_category=115

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  • will_10
    will_10 Member Posts: 4
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    whats a back flow preventer

    whats a back flow preventer and why does it say vent next to a hole were it looks like something should be screwed in there. Why is it attatched to a verticle copper pipe and a couple people told me it should be attatched to a horizontal pipe
  • Weezbo
    Weezbo Member Posts: 6,232
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    You sound like an adventurer *~/:)

    forget everything you ever wanted to do in life .... just write steam a couple times in your posts and you will be living here :)
  • burnerman_2
    burnerman_2 Member Posts: 297
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    it does what it says

    it prevents water from the boiler returning to any other part of your house bath sink ect any way i mostly put a copper pipe where u say something should be screwed in if it builds up pressure and pops off(the water run off) it would be directed to the floor i always installed mine horizonal not sure if it's ok vertical or not someone else may chip in thier 3 cents (inflation) royboy
  • burnerman_2
    burnerman_2 Member Posts: 297
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    it does what it says

    it prevents water from the boiler returning to any other part of your house bath sink ect any way i mostly put a copper pipe where u say something should be screwed in if it builds up pressure and pops off(the water run off) it would be directed to the floor i always installed mine horizonal not sure if it's ok vertical or not someone else may chip in thier 3 cents (inflation) royboy
  • ScottMP
    ScottMP Member Posts: 5,884
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    Burnerman is

    almost correct. It does not pop off due to a build up preasure.

    A backflow preventor protect the water supply from contamination from a non-potable supply. For most of us that means it stops boiler water from being sucked back into the house water. The most common examples would be a fire down the street and the Fire Dept. is drawing off alot of water creating a negative preasure in your house, or a water main break in the street, also putting your water main in a negative condition. In either case the backflow device would seal the boiler water from flowing back into the house water and the check valve inside would open up the the atmospere and allow air to enter your water piping.

    This happens because the backflow device has two small, spring loaded check valves that the water preasure seals in the direction of preasure. When the preasure drops on the street side or becomes lower than the boiler preasure they pull back and allow air to enter through the threaded port you mentioned.

    Since they are a simple spring check with rubber seals and a stainless steel seat, occaisionally, somtime due to a preasure drop or surge, they will drip alittle water. Thats why you vent them down to the floor. If dirt gets trapped under the seal they can leak alot and need to be changed/repaired.

    Its a small price to pay to protect the drinking water from contamination.

    I could find nothing about horizontal vs. vertical but thats not to say there is'nt a correct location for install. Hopefully some one will have that.

    Scott

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  • Dan C.
    Dan C. Member Posts: 248
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    doesn't matter

    They can be installed vertical or horizontal. At least a 9D can i'm not sure about other ones.

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  • tim smith
    tim smith Member Posts: 2,752
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    Backflow preventers

    We have to use double check backflow preventers w/ air gap, must be mounted horizontal, as if you mounted vertical the water would never enter air gap, would just dribble out edge of relief port and splash all over. Tim
  • ScottMP
    ScottMP Member Posts: 5,884
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    your correct Mike

    but that is just a small spring loaded check and not a true backflow device and there for does not meet most codes. A small it of debris could get caught in the check and you'd have no protection.

    Scott

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  • kevin coppinger_4
    kevin coppinger_4 Member Posts: 2,124
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  • nugs
    nugs Member Posts: 77
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    Not what's it's Watts.
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