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pingers7 03-13-2007 08:25 AM

poss. expansion tank?
i have had problems with this system in the recent past but fixed most problems, now i have a pressure problem i get about one half gallon of water dumped from the pressure relief valve every night and i get air noises(clanking) in the pipes. i have a one zone baseboard hot water oil boiler weil mclain only about 7-8 years old. on the expansion tank there is a schrader valve, when i push it i thought only air would come out but i get water does this mean the tank is bad? i thought there was a bladder in there to seperate the water and except pressure. if this is bad and i replace it will this also fix my noise problem? i still have heat. small house only 900 sq. ft.

only need to replace a couple more things and it will be a new system again. thanks for any help bob

redline 03-13-2007 03:57 PM

If you are getting water out of the expansion tank then the bladder has gone.

replace the expansion tank and this will solve the air and water problem.

You will have to bleed the air out of the system after the expansion tank is replaced.

pingers7 03-14-2007 07:19 AM

thanks for the quick response just a couple of questions. does the new expansion tank need to be pressurized (air put in), also what is the best way to bleed the air out? i do not have any bleeders on any baseboard units, two auto bleeders on the system and one elbow with a bleeder screw on the first pipe going up to the house, two drains one on the boiler at lowest point and one just above the expansion tank on the same line kind of. thanks again for you're help bob

hvactech 03-14-2007 05:18 PM

The expansion tank pressure should match the water pressure of the pressure reducing valve usually about 12 psi, in order to get a true reading out of the tank you must first drain all the water out of it and then pump till it reach the 12 psi, now if the pressure reducing valve failed and its allowing the water pressure in the boiler to raise then you have a different issue.

pingers7 03-14-2007 08:02 PM

thanks hvactech so i should pressurize the tank before i connect it to the piping, there should not be any water in the tank when it is new. 12 psi sounds right it says that on the side of the old tank. so you think i may have a problem with my pressure reducing valve? i feel that if water is coming out of the expansion tank at the schrader valve then the diaphram must have a hole in it so it can not allow any expansion of pressure does this sound right to you. well i hope this works. bob

hvactech 03-14-2007 08:10 PM

if you see water coming out of the schrader valve then the tank is bad for sure, now after reading your post again it seems like you found the problem.

mikemy6 03-20-2007 04:10 PM

I think you have burst the bladder check or replace youre PRV as you are not protected if its bad!!!!!!! check w/ gauge next time !

pingers7 03-21-2007 07:42 AM

just want to thank every one for helping me. running good now still have some air in the bedroom heater hopefully it will work its way out if not i will be draining the system in a little while (getting warmer outside). thanks again bob

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