Can't get pressure down

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  #1  
Old 09-18-12, 04:20 PM
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Can't get pressure down

Hi all,
I'm a long time boiler owner, but am having a "brain fart" on this one, and need some help...
I have a thirty-nine year old American Standard gas-fired hot water boiler for my two story house. It is all baseboard radiation, and I keep the system well maintained. I usually try to keep the pressure in the 12-15 pound range, but this year, it seems to want to stay between 18-22 pounds. There is an overhead horizontal expansion tank.
The water supply is currently off, so I know the pressure reducing valve is not affecting this.
I want to get this pressure back down, but am drawing a blank. I just need a nudge in the correct direction on what to check next, please.
Thanks!
Andy
 
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Old 09-18-12, 05:55 PM
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I'm a little confused....have you tried draining a little water out of the boiler to get it back down to the 12-15psi range? If so, does the pressure rise back up to the higher range when the boiler is hot, and then stay there?
 
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Old 09-18-12, 06:03 PM
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Sorry for the confusion, yes, I did drain some water, and the pressure stays up there.
 
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Old 09-18-12, 06:10 PM
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Sounds like your expansion tank has lost its air cushion. Drain the entire tank of water. They can trick you sometimes into thinking that you have it empty when the water stops draining because it hasn't been displaced by air.
 
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Old 09-18-12, 10:14 PM
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NEVER TRUST A BOILER GAUGE! If you have any hair, you won't for very much longer if you trust that gauge.

Please read:

http://www.doityourself.com/forum/bo...ure-gauge.html

Then we'll talk...
 
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Old 09-18-12, 10:17 PM
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By the way, does your boiler also provide domestic hot water via a 'thankless' coil insert ?
 
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Old 09-19-12, 09:34 AM
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Boiler does not have a domestic HW coil. I will try to do the gauge verification thing asap.
Thanks!
 
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Old 09-19-12, 05:14 PM
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NEVER TRUST A BOILER GAUGE!
Whoops! I forgot that one. I must be getting rusty.
 
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Old 09-20-12, 06:56 AM
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As the others have mentioned (was going to be my suggestion), don't trust the gauge.
When I finally get around to repiping my boiler (going PEX and cleaning up years of retrofits), I'll be adding a second pressure gauge after my temp/pressure combo gauge. Straight pressure gauges are cheap and easy to replace.
 
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Old 09-20-12, 10:55 AM
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No air cushion in your tank. The tank i believe your talking about is not an expansion tank, its a compression tank. If those become completely water logged they need to be drained down completely. Any pics would help. You have your water off. No tankless coil as well, probably the gauge like everyone is saying, but make sure your tank is empty.
 
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Old 09-20-12, 04:56 PM
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Thanks again guys. I have a nice 30# gauge I'm borrowing, but still need to make up an adapter. Been very busy at work, so haven't had much time to work on this. Hopefully I will in the next few days. Stay tuned...
 
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