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Thread: 35+ PSI boiler pressure. Have gone through the usual checks.

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    DIY Junior Member mdgolfguy's Avatar
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    Default 35+ PSI boiler pressure. Have gone through the usual checks.

    Hey Guys,

    I have a Burnham boiler with a Weil McClain indirect WH tank attached to it. I've noticed recently that water has been leaking from the PRV of the boiler and have seen PSI at around 35 at the high point. I've gone through the usual steps:
    1) I turned of the boiler and let the pressure hit 0. I read the expansion tank pressure and it was good, at around 12.
    2) I reduced the pressure to around 10 and shut off the cold water main to the auto feed valve. Pressure slowly rose over the next few hours
    3) I reduced the pressure to around 10 and shut off the cold water main to the indirect tank. Pressure slowly rose over the next few hours.
    4) Aquastat is set at 183. I have though seen it reach 220.

    Any idea what is wrong? Did I properly isolate the indirect tank and is my conclusion on that point valid?

    Thanks,

    Russ

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    Plumbing Contractor for 49 years johnjh2o1's Avatar
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    You may have two problems. It could be a bad auto feed. I realize your turning of the valve for the feed should eliminate the pressure from rising but the valve may not be holding.

    John

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    DIY Junior Member mdgolfguy's Avatar
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    my set up is like this: cold water main, shut off valve, backflow preventer, auto feed, shut off valve, expansion tank. If both shut off valves are closed wouldn't that rule a faulty shut off valve out?

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    Plumbing Contractor for 49 years johnjh2o1's Avatar
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    If you're turning a valve off between the boiler and the expansion boiler pressure will rise when the water is heated. You cannot isolate the expansion tank from the boiler.

    John

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    In the trades Dana's Avatar
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    If the expansion tank is undersized it can still hit high pressures when the system is up to temperature. What happens to the pressure when you turn off the boiler-fill valves and the cold feed to the indirect?

    You may still have pressure on the indirect from mixer valves elsewhere on the system- open a hot water tap somewhere on the system after turning off it's cold feed, just to rule that out.

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    DIY Junior Member mdgolfguy's Avatar
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    Quote Originally Posted by johnjh2o1 View Post
    If you're turning a valve off between the boiler and the expansion boiler pressure will rise when the water is heated. You cannot isolate the expansion tank from the boiler.

    John
    The valve is before the expansion tank

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    DIY Junior Member mdgolfguy's Avatar
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    Quote Originally Posted by Dana View Post
    If the expansion tank is undersized it can still hit high pressures when the system is up to temperature. What happens to the pressure when you turn off the boiler-fill valves and the cold feed to the indirect?

    You may still have pressure on the indirect from mixer valves elsewhere on the system- open a hot water tap somewhere on the system after turning off it's cold feed, just to rule that out.
    Expansion tank was fine for a few years.

    When the auto feed valve and and the cold feed to the indirect are both closed, the pressure still rises.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Some things like shower valves and many single handle faucets can allow backflow, and bypass the water feed to the indirect by feeding into the hot water outlet. So, you may have to turn the water to the house off if you don't have a valve on the outlet of the indirect.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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    DIY Junior Member mdgolfguy's Avatar
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    Quote Originally Posted by jadnashua View Post
    Some things like shower valves and many single handle faucets can allow backflow, and bypass the water feed to the indirect by feeding into the hot water outlet. So, you may have to turn the water to the house off if you don't have a valve on the outlet of the indirect.
    I have a valve on the hot water line that feeds out of the indirect.

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    DIY Junior Member mdgolfguy's Avatar
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    Also, I did flush my water heater fairly recently. Not sure if that means anything.

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    In the Trades Tom Sawyer's Avatar
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    With the auto feed off are only two things it can be. The expansion tank is bad or there's a leak in the indirect coil.

    Shut off the water feed to the indirect and the auto feed to the boiler. Drop the pressure in the indirect tank to below 12 lbs. fire up the boiler. If the pressure doesn't climb, the indirect coil has a hole in it.

    If the pressure still climbs, your expansion tank is bad.
    Last edited by Tom Sawyer; 05-29-2013 at 04:23 PM.
    [B]No, plumbing ain't rocket science. Unlike rocket science, plumbing requires a license[B]

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    DIY Junior Member bluefleetwood's Avatar
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    Quote Originally Posted by Tom Sawyer View Post
    With the auto feed off are only two things it can be. The expansion tank is bad or there's a leak in the indirect coil.

    Shut off the water feed to the indirect and the auto feed to the boiler. Drop the pressure in the indirect tank to below 12 lbs. fire up the boiler. If the pressure doesn't climb, the indirect coil has a hole in it.

    If the pressure still climbs, your expansion tank is bad.
    Can I assume you mean, "Firing Up The Boiler" by turning the stat on the Indirect Up to call for Hot Water?
    Sounds like I should be performing this test as well.
    http://www.terrylove.com/forums/show...p-of-t-P/page2

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    In the Trades lkgproducts@gmail.com's Avatar
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    You can test that boiler with the all purpose pressure tester

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    In the Trades lkgproducts@gmail.com's Avatar
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    Quote Originally Posted by lkgproducts@gmail.com View Post
    you can test that boiler with the all purpose pressure tester
    have you ever heard of the appt testers and kits?

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    DIY Junior Member bluefleetwood's Avatar
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    Quote Originally Posted by lkgproducts@gmail.com View Post
    have you ever heard of the appt testers and kits?
    No I haven't, Where do I acquire one?

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