Air Purge Valve will not stop dripping


Old 01-20-15, 05:20 PM
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Air Purge Valve will not stop dripping

Greetings all,
I'm trying to help my cousin with his furnace. House is a Cape and it's a forced hot water (baseboard) system. Attached photo is just something I grabbed off the internet but it's almost exactly what he has.

Furnace is oil
Temp gauge of furnace reads approx. 80-85
Pressure gauge reads approx. 15-20PSI

Above the expansion tank is a bleeder valve assembly. (see pic) The very top little cap is adjustable and it is continuously dripping water. I've tried adjusting it everywhere from completely tight to completely removed. It still drips the same amount of water at the same rate.

I understand this device to be there to let air bubbles in the system escape? I'm not sure why it keeps dripping water. It's been doing it for several weeks. I hate throwing parts at the system without a proper diagnosis but I'm not sure if I need to just replace the small pressure release assembly at the top or if this points to a larger system problem; e.g. the expansion tank.

Any help would be appreciated. I tried to research it online and the only thing I could find was if it was a bad expansion tank the pressure would be way off. The pressure seems normal.
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Old 01-20-15, 07:29 PM
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From what I see on Taco's site, it probably has a bad seal which is allowing some water to bleed off, along with the air. Replacements appear to be under $10.
Old 01-20-15, 07:52 PM
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Replace the cap with a high quality (metal) tire valve cap for now. Next summer you can replace the entire air vent assembly.

Also, you are in the wrong forum, this is for forced warm air systems. You should be in the boilers forum.
Old 01-21-15, 09:42 AM
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Thanks for tip but I'd just assume get this fixed now. I didn't make the connection between boiler and furnace...
Old 01-21-15, 07:11 PM
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While you are replacing the vent it would be a very wise choice to also make sure that the expansion tank has proper charge.

Step by step instructions here:

"Maid-O-Mist" #67 will replace that vent.

Things can go very wrong when you're working on stuff you've not worked on before and don't have full understanding of.

Take Furd's advice and wait until Spring time.
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