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Leaking Relief valve

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Uni R
Uni R Member Posts: 663
in THE MAIN WALL
If your expansion tank is pooched, then that may have caused the old one to activate, and then it continued to leak afterwards. Is the new one leaking while you aren't looking at the pressure gauge? I'd check to make sure your expansion tank is okay.

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  • Mark Porfido
    Mark Porfido Member Posts: 4
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    Leaking relief valve

    Hi,
    I recently replaced my boilers 30 psi pressure relief valve because it was weeping at a system pressure of 20psi. When it continued to leak I drained some water from the expansion tank again without success. What am I overlooking?
    The water temp is about 175.
  • Mark Porfido
    Mark Porfido Member Posts: 4
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    Yes, it continues to leak at the same pressure the old one did. How do I confirm the expansion tank? I see no leaks nor do I hear rushing air from it when I refill it.
  • John Starcher_4
    John Starcher_4 Member Posts: 794
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    You need to..........

    ....make sure you are reading the ACTUAL system pressure. If you are just going by what the boiler guage says, there is a very good chance that it is wrong, as these guages are notorius for being inaccurate.

    I have a guage that I keep on my truck - 0-30# range, with a female garden hose adapter attached. I screw this to the boiler drain valve, then open the valve to read the system pressure.

    Starch
  • Weezbo
    Weezbo Member Posts: 6,232
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    John,

    dont get me wrong here buh i used to connect the gage to the boiler drain too until i ran into two of them that were so clogged up it was a wonder water ever came thru the thing in the first place.

  • John Starcher_4
    John Starcher_4 Member Posts: 794
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    I agree, Weez.......

    ....and that is always a possibility.

    The boiler drain, though, is the quickest and most convenient place to attach a guage. If I'm ever concerned about "crud" in the valve, I flush a small amount of boiler water out first.

    Starch
  • Mark Porfido
    Mark Porfido Member Posts: 4
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    Ok, I suppose the pressure gauge could be faulty but the temperature gauge too? If the temp gauge is accurate and the actual system pressure is above 30# with a temperature of 175F then everything points towards the expansion tank, correct? The tank itself does not have a bladder so I was wondering how much water should be drained from it.
    Thanks much for everyones help.
  • John Starcher_4
    John Starcher_4 Member Posts: 794
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    Yes.

    The temperature guage could be just as inaccurate.

    If you have an isolation valve between the boiler and the expansion tank, try draining it completely. Also make sure that you do not have automatic air vents anywhere in your system, as they can cause the expansion tank to become waterlogged. This will cause your system pressure to become excessive when it's hot, and the relief will leak.

    Starch
  • Weezbo
    Weezbo Member Posts: 6,232
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    John *~/:) interested in some 145degree 12 lbs...

    pre stuck gages ? good thing about them they always tell the same story :)
  • Mark Porfido
    Mark Porfido Member Posts: 4
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    Well, there is an automatic air vent immediately adjacent to the relief valve, tee'ed with it. But this shouldn't allow air in the expansion tank to escape, correct?
  • Richard_12
    Richard_12 Member Posts: 7
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    Boiler Pressure

    On tanks that are is not a bladder tank must be drained completly before turning on the water. Also check the feed valve to make sure it is not leaking by. put a gauge on the boiler drain, turn off all the line going to the system from the boiler. leaving the main water valve on going to the boiler and let set to see if the gauge starts to move.
  • John Starcher_4
    John Starcher_4 Member Posts: 794
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    Yes it can.

    "But this shouldn't allow air in the expansion tank to escape, correct?"

    I'm not good enough with words to explain it well. I think there is an article in "Hot Tech Topics" on this site that gives a very good explanation.

    Basically, with a non-diaphragm expansion tank, you don't want ANY auto vents in your system. Period. As George would say, "FACT."

    Remove the auto vent and replace it with a coin, or manual, vent. Drain your exp. tank, open your feed valve and allow the system pressure to stabilize, verify your system pressure with another guage, and I bet your problems will go away. Also, you may want to verify that your automatic fill valve is not leaking through. This can cause over-pressurization of your system.

    Starch
  • John Starcher_4
    John Starcher_4 Member Posts: 794
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    Ebay maybe?????

  • John Starcher_4
    John Starcher_4 Member Posts: 794
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    Found it!!

    Here's the link:

    steel expansion tanks and air

    Like Dan says, "It pays to wander off the wall."

    Starch
  • Uni R
    Uni R Member Posts: 663
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    Autovents - It does allow air out of the tank...

    Water and air are in the expansion tank. Some of that air goes into suspension and gets carried out with the water. The air when circulating escapes through the autovent and then there is less air in the expansion tank and this is made up through the feed if it is on. The air that doesn't escape often ends up in the branches that you have to bleed.

    If you can, get rid of the conventional tank. Put a bladder style expansion tank on the suction side of the circ and some form of air eliminator, even just a tee with a vertical rise and an autovent on top will work.
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