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tconkey 01-27-2008 07:25 PM

Old Hot Water furnace won't hold pressure
 
I have an old oil-fired hot water furnace heating an old three story house. Every couple days I have to go down into the basement and add water to bring the pressure up high enough to provide heat to the third floor. Once pressure is added and the radiators on the third floor are bled, they put out plenty of heat ... for a couple days.

I don't see any evidence of any of the radiators leaking, no evidence of leaking pipes in the walls or anywher else, and no evidence of water leaking from the furnace.

Do I perhaps have to adjust the pressure regulating water valve? Do these things go bad? I had some problem last winter, but this year it's worse.

I'd most greatly appreciate any ideas anyone might have.

sgthvac 01-27-2008 07:30 PM

Sounds like your pressure reducing valve is bad or needs adjustment. There is a screen in it if you take the big nut offn the bottom off and clean the screen it might help, but chances are the pressure reducing valve needs repalced. Good Luck

bigMikeB 01-28-2008 05:59 AM

Do you raise the pressure back up after bleeding the air out? I would go with replacing the PRV if you don't see water anywhere but still think you will find a leak on careful inspection.

Mainah 01-28-2008 06:01 AM

water is leaving somewhere...

is your releif valve piped directly to a drain? Stay and watch your boiler go thru some cycles, whats the high temp when the burner shuts off? is it getting so hot it's actually boiling and making steam?
How are you adding water, a manual feed or do you have to fiddle with the auto feed valve to get it to start feeding? if the latter your feed valve is likely plugged and is not able to keep up with the water that is leaking out somewhere.

**have a buddy at the boiler while your bleeding and have him maintain the pressure as your bleeding the upstairs (with 3 floors I would reccommend 20 psi @high temp)


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