Need Advice RE: Purging Air From Baseboard Hot Water Heating System - HVAC - DIY Chatroom Home Improvement Forum

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Old 01-19-2011, 02:47 PM   #1
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Need advice RE: purging air from baseboard hot water heating system

I purchased a home that has baseboard hot water heating, two zones.

For one of the zones, there are two pipes within the baseboard, it comes in to the room on an upper pipe which goes around the room then bends and goes back through the bottom of the baseboards (the lower pipe has the metal fins around it) to get back to the boiler.

there are no bleeding valves on the baseboards, but in this zone the top pipe gets hot and the bottom one stays cold.
I can't get this zone above 61-63 degrees.

I do have a bleeding valve above the circulator (there's one circulator for the whole system)

I have located my two zone valves, those seem to test out ok, both of them get hot on the other side of the valve when i manually open them.

What is the best approach to get the air out of the problematic zone?
I was thinking the best way is to close the send and return valve for the working zone, close the valve above the circulator and open the bleeding valve and the feeder valve for that zone.

I was then going to use the "fast fill" valve to purge the air out of the system by pushing water through with the bleeding valve open. My problem is it seems my fast fill valve is broken or doesn't provide enough pressure even when it's lifted to the vertical position.
I don't know much about heating systems, i've just been picking up info while looking in to this problem. To be honest i dont know if the feeder valve shown in picture #1 is even supposed to be able to force the air out of the system.

When trying to purge the air like this eventually nothing was coming out, i was able to get it to push some air out and water then eventually the water stopped coming out of the bleeding valve.

When i closed everything up the system came back up to normal pressure (12-15psi) so it seems the feeder valve is working but i can't use it as a "quick fill" to force the air out of the system.

There's also a drain valve on the bottom of the boiler.
Is it an option to hook up a garden hose to the drain valve at the bottom of the boiler and pump water in to the system from an outside water faucet through that valve?

I've attached a few pics of the system that shows the fast fill valve, bleeding valve and the lower valve.

thank you.
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Need advice RE: purging air from baseboard hot water heating system-2011-01-14-10.20.59.jpg   Need advice RE: purging air from baseboard hot water heating system-2011-01-14-10.20.18.jpg   Need advice RE: purging air from baseboard hot water heating system-2011-01-14-10.20.34.jpg  


Last edited by mikenri; 01-19-2011 at 03:08 PM.
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Old 01-19-2011, 07:04 PM   #2
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(copied from another post)

Are you sure there are no bleed valves? Check for screwdriver adjustments on the heat pipes, not necessarily one in the baseboard in each room. These may be bleed valves.

Check the heating system expansion tank, empty it out, then put it back, refill the system, and turn the system back on. (There are other more precise ways to calibrate the expansion tank, but you would need more heating and plumbing system experience.)


The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.
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Old 01-19-2011, 07:17 PM   #3
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Not that i could see.

I took the end caps off all the baseboards.
on the far end the pipe just bends back in to the lower portion, the pipes are seperated on the side where it comes in to the room.
It goes through a closet and the piping is all covered by pipe insulators, i'll look under there and see if there are valves.

i've read some systems get installed without the valves and you need to bleed it at the boiler but it seems i just can't get enough pressure from my fill valve to push all the air out, it's the lower zone in the house.

i will check out the expansion tank. since the top pipe in the problem zone is hot a portion of the way around the room then it gets cold after a certain point i was thinking the problem was air was blocking the water from flowing properly.
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