Boiler heating airlock problem


Old 04-21-03, 07:40 AM
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Boiler heating airlock problem

Good Morning.

I've got a boiler heating system with 3 zones (quad level home). The 2 bottom zones are fine, but the upstairs zone appears to have an airlock in it. I've looked at every radiator, and there are no bleed valves.

On the boiler, there is a 'bell' which I think lets out air out through a small "jiggle-cap" (yeah - I'm highly technical .

Anyway, my plumber hasn't been able to solve the airlock in the top level, and hasn't been returning my calls. Late last night the upstairs (top level) pipes started really banging and woke me up. I went downstairs, and the jiggle cap had blown/fallen off and a small but steady stream of water was dripping from the bell. I opened one of the lower zones for a moment and the banging stopped and hasn't re-started, but I turned off the entire boiler for the night because I can't find the "jiggle-cap". I think it rolled under the boiler.

I didn't want the water dribbling out all night (and day while I'm at work) so I just shut the whole thing off.

My plumber - before he disappeared - suggested the pump wasn't strong enough to push through the airlock upstairs. Is this possible? According to tags on the system when I bought the home 3 years ago, the boiler was replaced in '82 and I've had all 3 zone control modules replaced last year (which may have created the airlock - OR it might have been when I had an upstairs radiator removed so I could put in a doorwall to a new deck. Both operations occurred in the summer within a few weeks of each other). I don't know the real age of the furnace.

1. is this cap something I can buy at a plumbing supply store?
2. it's suppose to drop to the 40's tonight, can I turn the furnace back on if the water is still dribbling out? (there is an open 'refresh' tap to the boiler)
3. is it possible the pump needs replacement because seals or age has weakened it to the point that it can't pump all the way upstairs?
4. Is there someplace where I can get detailed instructions on how to deal with airlocks. I have no reference material on this type of furnace.

Thanks for your help!
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Old 04-21-03, 10:32 AM
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Lot of if's and and's here . Did the plumber get water out of the top radiator and bleed the whole set up then???Whats the psi there on the boiler??? On the water pumps they are just so called circulation pumps.So if your plunber said that they aren't strong enough. I think I would look for another plumber. There is an impeller in the pump that can go out but I have only put 2 in in 35 years ED

Where are youuuu KField
Old 04-21-03, 02:53 PM
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Just a thought here. Did this thing work correctly since the removal of the radiator? If not, someone may have capped the pipes and not continued the loop through. Depending on the piping of the system, it is likely that the pipes for the removed radiator should have been connected together under the floor to maintain the continuity of the zone. That work would have definitely caused the loop to get airbound. If you don't have individual bleeders on the radiation, you may have to purge the loop. Assuming the zone valves are on the supply side, look for a valve near the boiler on the return pipe to isolate the boiler from all 3 loops. Then on the loop side of that valve, look for a valve that you could connect a garden hose to. That combination constitutes a purge setup. You should turn the boiler off, close the valve on the return, manually open the zone valve on the loop to be purged and open the drain valve on the return line. You will then be pushing air and water all the way through the zone and out the drain valve. You may need to let water flow for a few minutes to clear all the air. You should maintain 10-15 psi of water on the gauge during the process to get enough water velocity to carry the air back down and out.

The banging you are hearing is probably steam. Yo may be running the boiler at a high temp and with a low pressure. Check those numbers and get back to us. The cap on the air vent may not be a standard thread either. You might have to get down on your hands and knees ans find the original. The steam coning out the air vent probably jarred it loose and shot it across the room. Just close it if it continues to leak. You have more serious problems to resolve first.

Old 04-21-03, 04:14 PM
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Unhappy Photo

Can you post a digital picture of the thing with the cap, it just might be a standard auto air vent. Is this hot water or steam, it sounds like hot water BUT with the banging sound your describing steam condensate....oh, check the temp and pressure on the boiler...Some might think well he has a circulator...but, this might be steam with a hot water coil below the watrer line with a circulator pump, so indulge me.....also, is there a gauge glass tube to indicate a waterline???
Old 04-21-03, 05:38 PM
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the bell thingy that you are rfering to sounds like a normal tin can air vent...most common is the good old #67....they clog or fqail regularly, and in most installations is put in a spot that is totally worthless for eliminating air from the system. replace the whole thing they are about 12 bucks if that much......but remember if you have to drain the system to do it you will have to bleed the system when you are far as the pump is concerned if you have an average house with three zones a basic B&G series 100 or a B&G little red pump or a Taco 007 is more than enough you don't need a new pump especially if the other two lower zones work ok...rem3ember the job of the pump is not to lift water it is to circulate it. air is your proble...many systems have a hose bib near the zone valves...hopefully above each one. turn the system off.....hook up a hose to the problem zone and open the the same time open the fast feet valve usually there is a lever on the pressure regulator....force water through the problem zone this should force the air out of that loop and your heat should be restored to that zone......but if all else fails call your local heat contractor to bleed it.
Old 04-22-03, 06:05 AM
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Airlock problem found (solved?)

Thanks for the replies to my problem guys.

I gave up on my plumber (after 6 weeks and $700, he still hasn't replaced the guest shower he was hired for - that issue is still pending), and called in a local plumbing company who had replaced the zone valves last summer.

It turns out the boiler was DRY. Apparently the valve off the water main feeding the boiler was ok - but the valve that regulates how much gets delivered to the boiler was defective. Over the winter, water was slowly being lost through the hot water expansion tank (with the air relief valve - also known as the "Jiggle-thingie"). The major pipe pounding I heard was steam.

Fortunately, I turned the whole furnace off and prevented a bigger problem.

Once the new expansion tank (and built in valve) was replaced, everyhing seemed OK - except all three zone cut-off valves started leaking. Since the furnace is nearly 40 years old (though the boiler was replaced in 82) I'm looking at replacing the whole thing with a modern furnace. My heating bill was nearly 300/month (Nat. gas) and I could use the increased efficiency.

This web-site is a great resource and I'm glad I found it. I plan on using it a great deal in the future. As much for research before I contact a contractor as anything. Everyone wins when you both speak and understand the same language, terms and theories.

Thanks again.
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