pressure tank blowing off steam


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Old 03-31-10, 02:16 PM
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pressure tank blowing off steam

returning from vacation and turning on boiler,hot water type,went on normally and shut off at the cutoff of 220 degrees and minutes later the pressure tank blew off steam,measured 8.5 psi at the pressure tank,could this be the problem?how do I know when the system is full?any ideas would be appreciated,thanks in advance.
 
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Old 03-31-10, 03:24 PM
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Can you post some photos on a "free image hosting" site, and link them here?

What is the usual high-limit set at? The 220 deg must be a hi-hi-cutoff?

Did the relief valve lift? Look at the nameplate - what is its pressure setpoint? Surely not close to 8.5 psi? It almost sounds like instead of a pressure relief valve, you have a combined P-T safety valve such as used for a closed water heater.
 
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Old 04-02-10, 03:54 PM
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blowing off steam

my expansion tank says 12-15 pounds,the safety valve on the boiler did not blow,just the valve on the expansion tank did,i,m guessing the boiler needs water as i have a on-off valve and when i cut it in the water starts filling the boiler,the auto filler doesnt seem to be working althoufg it was changed out last spring,have the system anti-freezed so dont want to keep filling,any ideas,thanks
 
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Old 04-02-10, 05:39 PM
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Valve on the expansion tank?

You really need to show us what you are talking about. Doesn't make sense.

Take some pictures and put them up on a hosting site like photobucket.com and link to them so we can view.
 
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Old 04-04-10, 06:10 AM
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blowing of steam

sorry cant take any pictures,yes the valve blowing off is on the exspansion tank,the blowoff valve on the boiler itself does not blow off,I found that the exspansion tank at cold,0 degrees measured 8.5 pounds brought that up to 12.5 pounds.turn on boiler from cold runs around 8 minutes and the temp on the guage measures between 200 and 220 degress and the valve on the exspansion tank blows off steam so i turn off the boiler,it does turn itself off at the hi cutoff of 220 degrees.what I do find that I have a cutoff valve before the automatic filler and its off,now i realize it shouldn,t,when I turn it on water feeds into the boiler ater awhile while its still going in I shut it off as I have anti freeze in the system and afraid thai I am diluting it too much.I do notice that the pressure on the guage reads 8 psi I do beleive it should read around 15 psi indicating the water level is ok,is this correct? If there wasn't enough water in the boiler itself would that cause the exspansion tank to blow off?thanks for the help you guys offer us,much appreciated.
 
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Old 04-04-10, 08:43 AM
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I'm sorry, but I have no idea what you are talking about!

If you can't take pictures, can you at least tell us the make/model of the boiler, and any other equipment labels that you can find on the system?

Maybe this is a steam system? and what you think is the expansion tank is really a condensate tank? I dunno... something is uhhhh... unusual here.
 
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Old 04-06-10, 10:27 AM
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blowing off steam

.it is a burnham steel boiler,fhw system with amtrol ,extrol model 30,anyhow thanks for your help will try talking to people,one question,the system has anti freeze in it,would like to see what temperature it is good for?can you use a regular car anti-freeze tester?if not what do I need? dont know how else to explain the problem I apologize for that.
 
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Old 04-06-10, 11:01 AM
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OK, an Extrol tank does not have a relief valve on it. One end of the tank has the 1/2" pipe threads and 'usually' screws into the bottom of an 'air scoop' of some sort. The tanks should be installed so they are 'hanging', and on the bottom is the schrader valve where you check the air charge. On top of the air scoop may be a float type automatic air vent... looks like a brass can, about the size of 'red bull' ... small cap on top of that can... is this what's blowing off the steam?

In any case, it sure sounds like you don't have enough water in the system... if you are blowing 'steam' out of a vent. And, something else is way wrong if the system is getting up to 220 degrees...

I don't mess with AF, so can't tell ya how to check... I'm sure one of the other guys will be able to... I think it may also be important to check the PH of the mix as well.
 
 

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