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Auto boiler feed valve??

GChuck Member Posts: 1
Hello. I've had this system for a few years and it has started to give me some trouble. The pressure in the system keeps falling and I have had to add water manually by turning the valve in the photo. ( nut has loosened up a bit so there was a slow drip causing cruddy looking handle, nut now tight). The fitting that has the valve handle and is also connected to the expansion tank is something I have no seen before. Is this an autofill valve that depends on pressure in the expansion tank to work? The expansion tank sounds "solid" to tapping and when I depress the shrader valve, nothing comes out (water or air), imagine the tank has ruptured inside and the schrader valve is corroded. The system was plumbed in a way that makes replacing the tank pretty difficult. I'm thinking of redoing all the plumbing but if this fitting can be serviced (cleaned?) and a new tank screwed on it might still be easier. Any advice / knowledge appreciated.


  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
    May need to see more pictures, but obviously if your having to constantly fill, you have a leak that needs to be addressed, sooner then later, before fresh make up water kills your boiler.
    If no air comes out of the shrader valve, the tank is bad, or at least lost its charge. The valve wouldn't be corroded from water as no water should come out the valve on a properly working bladder tank.
    I imagine you need water because you keep popping the relief valve and losing water.
    You truly need a competent hydronics person to come out and assess the situation.

    There was an error rendering this rich post.

  • HomerJSmith
    HomerJSmith Member Posts: 2,468
    You have hard water. Hard water is hard on fill valves of any kind. If that is a fill valve the red handle should be open all the time and the auto fill valve would stop filling the system when the pressure in the system equals the air charge on the air side of the tank. It doesn't take much water loss to drop the pressure in the system. That water loss may not be a leak in the piping, but water flowing into the expansion tank because of a loss of air charge in the EX-tank. If that's the case, water will be coming out the pressure relief valve on the boiler as the boiler heats up. This is because there isn't any acceptance volume in the EX-tank.

    The tank looks old, I would replace it. You would have to do some re-piping as your existing tank is on the floor. Make sure that the air charge on the tank is between 12-15 psi. Try an Amtrol Filtrol 110 tank.

    You might have to add a 1/2" ball valve on the boiler feed pipe before the EX-tank. The old tank has a shutoff valve built into the fill valve.
  • hot_rod
    hot_rod Member Posts: 22,268
    How much water are you adding, how often? Any signs of a relief valve seeping? maybe into the PVC drain?

    Maybe buy an accurate pressure gauge, 30 psi and pressurize the system and observe for a day or so.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • the_donut
    the_donut Member Posts: 374
    Almost looks like that valve to compression tank is closed. If it is, then there is no pressure in the tank. That’s why you get nothing out of the schrader valve.