Re: hotwater/expansion tank questions

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Posted by Chadwick T. Morgan on October 06, 2001 at 06:21:34:

In Reply to: Re: hotwater/expansion tank questions posted by roger on October 05, 2001 at 14:47:38:

I'll check that out - but that would imply a possible leak almost anywhere from the supply line to the tank and/or boiler, couldn't it?

I called Bell and Gosset yesterday afternoon and tried another way - I followed their S10300G service manual on the airtrol valve (drain tank, refill, etc. - note I have an isolation valve from the boiler to the tank - I shut that as well isolating the tank - then opened that isolation valve, allowing water to settle into the tank from the loop - then opened up supply)- except after running supply carefully into the tank, I then shut off supply and ran the boiler with supply still shutoff, observing how the pressure builds. At about 24 psi and obviously slowly creeping to high pressure, I manually tripped the relief valve, dropping the pressure down to 20. I did this only once. The upward creeping of the system slowed quite a bit - I then opened up supply (runs through the PRV of course - re-adjusted the setting of the valve to 12 psi after much mucking around).

I ran it this way for about 2 hours till I finally went to sleep. It was slowly creeping upward.

Am trying again this morning - 33 in O'Hare airport. About the same in the far northwest suburbs where I am at.

: Talked with someone that thinks the drain valve on the expansion tank could be leaking air around the packing nut. This would let the air leak out(and not water) until the tank fills with water and then over pressure occurs and no visible signs of leaking. Makes sense? Maybe!!

: : I have the same sort of problem. The PRV appears to be fine, keeping static room T pressure at about 12 psi. There is a cutoff between the expansion tank and boiler - the expansion tank is above head in the basement and is fitted with an B&G airtrol valve. I have followed B&G's online manula to the "T" and implemented my own procedures and I still connot keep the expansion tank from refilling.

: : My boiler supply is directly from my hotwater heater, using well water at about 40-50 psi. The PRV is not blocked - prior to my purchasing the house, I ran the circulator pump and boiler - while cool, the boiler maintained the set 12 psi. I have since drained quite a bit of water and it refills appropraitely. But when I do the expansion tank draining (using several methods because none have worked so far) I will open the supply line - and hear the tank refill as if there is a hole on top - but absolutely no leaks I can determine - if it is an air leak, I think it would have to be small, but then would take several hours/days to allow water to fill the tank.

: : So, when I fire up everything, I eventually hit 30+ psi and the relief starts to go. I have purged radiators per known procedures, as well.

: : What gives? I am near Chicago and we are in for colder weather shortly. I am an ex-navy machinist mate and now an engineer, so please, anyone, speak in whatever terms you wish but I need some quick advice. Thanks, C

: :
: : : I've notice this heating season that my boiler psi is running around 30-35 and bleeding off excess pressure constanlty. I've drained the expansion tank and re-filled. This brings it back down to around 18-22 psi which is wher eit used to run at. Problem is that it gos back up after a day or so. Do I need a new expanion tank? Why is the pressure running so high?

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