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Filling Hydronic Boiler Through Drain Valve?

jeb21
jeb21 Member Posts: 6
edited June 2021 in Radiant Heating
Is possible to refill makeup water by using the drain valve. I read a post somewhere that suggested this, but, I don't want to cause any damage.

Any help would be greatly appreciated. Thank you!

Comments

  • jeb21
    jeb21 Member Posts: 6
    Is it possible to hook up a hose to the drain valve and add water?
  • Jamie Hall
    Jamie Hall Member Posts: 18,924
    Not a problem to fill through the drain valve -- or anywhere else you can get at, for that matter. You may find that the easiest thing to do is to make up a nice hose with female fittings on both ends and run from a handy bibb to the drain valve.

    The sequence of pressure reducer/backflow preventer is fine as is. However, the drip from the backflow preventer's vent indicates something is amiss in the backflow preventer. That type can, I believe, be serviced -- but it's going to need that, or replacement.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    mattmia2jeb21
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 11,992
    Sorry to disagree with @Jamie Hall and i didn't know this until recently as well but the backflow preventer must be in the water pipe before it goes into the pressure reducing valve.

    As far as filling through the drain valve that is fine
    mattmia2jeb21HomerJSmith
  • Steamhead
    Steamhead Member Posts: 15,331

    Sorry to disagree with @Jamie Hall and i didn't know this until recently as well but the backflow preventer must be in the water pipe before it goes into the pressure reducing valve.

    As far as filling through the drain valve that is fine

    This.
    All Steamed Up, Inc.
    Towson, MD, USA
    Steam, Vapor & Hot-Water Heating Specialists
    Oil & Gas Burner Service
    Consulting
    jeb21
  • mattmia2
    mattmia2 Member Posts: 5,512
    I assume that is a converted gravity system?

    My question would be where is the water going?

    Filling through a boiler drain is fine. might want to purge the hose before you connect it so you don't add much air in the process.
    jeb21
  • Jamie Hall
    Jamie Hall Member Posts: 18,924
    Thank you all for the correction -- I didn't know that either!

    Why we come here -- to make sure we know what we are doing.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,190
    The connections to the BFP and PRV are unions with gaskets on both ends. The end on the system side is brass to steel pipe. in 90+% of the time, the brass fitting is not a problem removing the brass union adaptor from the steel pipe. If the water is cooled below 100'F (so not to scald) and you drop the boiler pressure, you can back out the BFP union from the steel pipe and have a ball valve ready to put back in about a second... loosing only a few ounces of water. I can detail the step by step procedure if you are interested.

    Looks like there is enough room to replace the old setup with a pre-assembled Watts 911 and use the old union nut on the supply (copper) side and have room for a ball valve and close nipple on the system side.

    With valves on both sides, future repairs will be much easier.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
    Intplm.
  • jeb21
    jeb21 Member Posts: 6
    mattmia2 said:

    I assume that is a converted gravity system?

    My question would be where is the water going?

    Filling through a boiler drain is fine. might want to purge the hose before you connect it so you don't add much air in the process.

    Yes, converted gravity. I don't think I'm really losing water, the pressure barely dropped, and my house is small, I would have noticed if I have a leak somewhere.
  • jeb21
    jeb21 Member Posts: 6

    I can detail the step by step procedure if you are interested.

    Yes!!! I am interested. I would like to get this fixed, but, can't find a good example of how-to with this setup.

    I cannot thank you enough!!!
  • jeb21
    jeb21 Member Posts: 6
    Thank you all for your comments and suggestions. I am cooling down the boiler now and will fill it back through the drain valve ... repairs to come.

    Thank you for the quick responses, this site is awesome!
  • jeb21
    jeb21 Member Posts: 6


    With valves on both sides, future repairs will be much easier.

    I was thinking about doing this, but, my biggest concern with this repair is working on those iron pipes. I read some posts from another site that referenced the difficulty of knowing the proper tensions for tightening and I'm also concerned about breaking the existing connections.

    I am handy, but have only done very basic plumbing and pipe work (i.e. cut into a copper line to insert a sharkbite and ball valve for a new dishwasher). I would probably take this on without hesitation if it were all copper.
  • HomerJSmith
    HomerJSmith Member Posts: 1,562
    I always tighten pipes until they break and then I give one more turn.

    You might want to clean the double check as it is dripping and re-assemble in the order it was taken apart. Take pictures when dis-assembling it. You can lube it with silicone grease that you buy from the auto parts store. Dielectric grease.