Re: hotwater/expansion tank questions

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Posted by Chadwick T. Morgan on October 07, 2001 at 20:31:19:

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

well, I've tried and checked several things - to no avail. What is the best way to check the PRV? Can a PRV backflow? Our supply line is connected to the hot water heater - my fiance stated she had extremely hot water all through her bath today while I was fiddling with the boiler, even though I have dialed down the hot water setting (gas heater) - I may dial it down a lot further to almost off and then check the water temp at the faucet while running the boiler. Don't know why they hooked it up this way.

Anyway, if there is an air leak at the top (per jtown's suggestion, 10-06 post) I would think I would hear it because the water seems to fill the tank qute rapidly. I turn on the supply line after bleeding and I hear water rushing it quite quickly. An air leak of that size would have to release water, but maybe not. I cannot find any leak of any type anywhere (odd I am sure, but still true - they put this thing together pretty well).

More suggestions?

: 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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