Boiler Pressure Problem

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Old 10-23-06, 02:22 PM
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Boiler Pressure Problem

I have a 40 yr. old American Standard boiler. When setting idle (no call for heat) the pressure gauge reads 12 psi constantly. When the boiler fires up for awhile the pressure builds to 30 psi and then trips the relief valve. I have shut the valve off to the expansion tank (old canister type - 40 yrs old) and drain the tank completely. I then open the valve back up allowing the tank to fill up (cannot check pressure in expansion tank) until it stopped. I shut off the water valve comming into the pressure reducer valve and then fired up the system. The pressure still built up and popped the relief valve. I know the pressure reducer valve isn't leaking through because I have drained the whole system before and left all the drains open and nothing leaked out. Today, while downstairs I noticed the pressure was building up and temp was 195* F and my Temp Immersion Limit Control is set for 175*F. Is this symptomatic of a bad expansion tank?
 
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Old 10-23-06, 03:25 PM
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Wink

If you drain the expansion tank how does it fill right away as you say??? (cannot check pressure in expansion tank) until it stopped.
Do you have a bladder tank. Is the bladder bad???

while downstairs I noticed the pressure was building up and temp was 195* F and my Temp Immersion Limit Control is set for 175*F. Is this symptomatic of a bad expansion tank?

Id say more like a bad limit or aquastat there.

ED
 
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Old 10-23-06, 05:27 PM
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how do you know the expansion tank was empty?

i had similar problem and persistance in emptying the tank resulted in resolution of problem. when the water stops coming out you may have to blow air in tank and continue to drain till blowing air does not get anything out. see other posts with similar issues. my tank had a small needle valve to let air get in on the inlet to expansion tank.

Originally Posted by Ed Imeduc
If you drain the expansion tank how does it fill right away as you say??? (cannot check pressure in expansion tank) until it stopped.
Do you have a bladder tank. Is the bladder bad???

while downstairs I noticed the pressure was building up and temp was 195* F and my Temp Immersion Limit Control is set for 175*F. Is this symptomatic of a bad expansion tank?

Id say more like a bad limit or aquastat there.

ED
 
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Old 10-25-06, 02:34 PM
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There's no bladder in the expansion tank - 40 years old. The tank fill rather quickly, matter of a few minutes. No way to check the pressure on the tank, it only has a manual fill valve and empty valve, along with a bleeder nipple for air.

Another problem has cropped up. The circulator pump started leaking water from the bottom. Water is drizzling out from where the motor part of the pump connects to the housing part that connects between the feed pipes. I have a Ball & Gossett 100 Series pump. Is the pump worth having rebuilt? If not, what type of pump should I replace it with?

Thanks,
RCJB
 
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Old 10-25-06, 08:00 PM
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Circulator

Even with a re-built bearing assembly for the B&G 100, it is cheaper to replace the whole circulator. In most cases a Taco 007 will do the job just fine.
 
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Old 10-26-06, 07:46 PM
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I installed a Bell & Gossett NRF-22 circulator instead of having purchasing the bearing assembly for the 100 series circulator. I just finished installing it and running new electrical wires. Tomorrow I will finish installing the new Extrol #30 expansion tank. I will let you know how things work out.

Thanks.
 
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Old 10-29-06, 06:59 PM
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I replaced the circulator with a NRF-22 and put in an Extrol #30 expansion tank. I opened up the bottom of the pressure reducer valve to clean it, but the little screen inside fell apart. Can the scree be replaced or do you have to by the whole valve? I filled the system to 12 psi (pressure reduce valve automatically). I've been busy bleeding the baseboards. It seems that when I bleed the upstairs baseboard (one furtherst away) while it is calling for heat, I get air out at first and then a small stream of water, but then nothing. The water makes a chugging sound, like it's falling - I guess this is due to loss of pressure. Is it best to bleed the system while calling for heat or idle?

Thanks
 
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Old 10-30-06, 08:03 AM
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you must be really cold

interesting turn of events. i am not sure you needed to replace the expansion tank. emptying it completely might have solved the problem. you are trouble shooting too many parts at the same time to figure exactly where the problem is.

i think you can only bleed while circulator is on since water can't go against gravity. i am also learning so correct me if i am wrong.

Originally Posted by RCJB
I replaced the circulator with a NRF-22 and put in an Extrol #30 expansion tank. I opened up the bottom of the pressure reducer valve to clean it, but the little screen inside fell apart. Can the scree be replaced or do you have to by the whole valve? I filled the system to 12 psi (pressure reduce valve automatically). I've been busy bleeding the baseboards. It seems that when I bleed the upstairs baseboard (one furtherst away) while it is calling for heat, I get air out at first and then a small stream of water, but then nothing. The water makes a chugging sound, like it's falling - I guess this is due to loss of pressure. Is it best to bleed the system while calling for heat or idle?

Thanks
 
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Old 10-30-06, 04:04 PM
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Screen/Bleeding air

You will have to get real lucky to find a screen for the reducing valve. Your's would not be the only one with no screen.

The lack of flow when bleeding could be due to lack of pressure.
If this is a two story house, you should be at about 15#.

Bleeding air is a trial & error thing. Sometimes best done with the circulator running, sometimes not. I always start with the circulator off.
 
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