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Why have fill valves?

Bob Cat_2
Bob Cat_2 Member Posts: 14
I read all the comments on the fill valve post and I personally let the H.O. decide if they want it off or on.(usually I leave them off)

It makes me wonder why use one if I'm going to leave it off. I can regulate the pressure when I fill it with a valve. I think one of the code requires that a valve be installed to allow the boiler to operate at a safe pressure. Does any one out there not use a prv an a boiler?

How does something like this get addopted to a code? In the past when it was original designed was it intended to be left on and then years later it was found that its better to leave off?


  • c-rex
    c-rex Member Posts: 48
    PRV/to use or not to use

    that is the question. If the home owner wants a fill valve,
    they are also buying into a back-flow preventer. With the advent of the fast fill feature on both the B&G and Watts valves, it make a system start up puge really easy. Shut them puppies of for six or seven seasons and try to get them to pass water......Bottom line, they are handy when you are venting, a true witch as they age, and a master pain when they fail/overfill and run water across the basement on the way to the floor drain. I evaluate the situation, discuss it with they home owner and use them 50% of the time. Good luck
  • Rob T
    Rob T Member Posts: 64
    Being a HO

    my main reason for a PRV is convenience. If I notice a low pressure problem it is just a lot easier to flip the shut-off open and know that the incoming pressure isn't going to pop the relief valve. (Assuming the PRV has not stuck...)


  • heretic
    heretic Member Posts: 159
    Why auto fill valves?

    My guess:
    Old CI rads have air purge valves.
    Would be difficult to fill/purge them without the FVs.
    Would otherwise take 2 people and a radio, or a lot of yelling (or running) to get it done. For most old house owners, purging is a seasonal ritual (or worse).
    The FV also encourages the HO to not set the system pressure too high.
    Seems rare for an old iron system to have zero leaks, plus there are a lot of circs placed on the return out there.

  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    Standing Iron Systems

    Is what you said EVER true. It is a NIGHTMARE and usually a MESS to fill them without a PRV.

    Try three or four people if the boiler is in the basement, the top rads are on the 3rd floor and the temperature/pressure/altitude gauge is way on the other side of the boiler...
  • bobcat
    bobcat Member Posts: 1
    ok good point!

    I think csnow and Mike brought up good points about CI radiators. I usually do new construction and was thinking about baseboard systems where i usually have the purge set up right at the boiler. No need for vents anywhere else. Anyways they were all good responses thanks.
  • Ruthe  Jubinville
    Ruthe Jubinville Member Posts: 67
    Fill valve

    One contractor said at a seminar i was at, to use them so the people that make them can make a living
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