Baseboard Heating - Air and other Oddities, Can you help?

Old 02-25-05, 06:51 AM
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Unhappy Baseboard Heating - Air and other Oddities, Can you help?

Hi. I've got a crane gas-fired boiler providing baseboard heat to 4 zones in my home, each with its own Taco valve. When we moved it, two of the TACO valves were replaced, along with the grey accumulator (pressure relief?) tank and the little air-release valve (with the small red plastic cap) that sits lightly on top of it. This was because the system kept getting more and more pressurized.

Eventually we discovered that the automatic valve that lets water into the system from the main cold water line was not closing. Since there was a manual valve in line with that one, shutting off the water supply to the boiler solved the over-pressurization problem. I keep an eye on the pressure and if I see it ever dip low, I can add water into the system by opening the manual valve and then manually opening the sticky automatic valve to force water into the system.

Thats the "background"..but here is the problem:
I shut off the boiler each summer....then in October when we turn the heat on, all is usually well. But every year, like clockwork, by the time Jan and Feb roll around (when the heat is running alot), I get loads of air in my system, keeping us all up at night. I have no idea why..the air just appears.

I go from the nice "tinkling" of the baseboard vanes expanding, letting me know the heat has come hearing this never-ending waterfall of gurgling water, and the expanding vanes, which many times wakes me up at night. Gah!

I dont notice any drywall falling down or water leaks, so I'm hoping I'm ok there!

The pressure (when the heat is on, but not running) is around 8-12 psi. When its running, it maxxes out around 20psi. I have NO IDEA what the pressure in the system is supposed to be, nor do I know of any way on this boiler to adjust it.

My question is this: What is the best way to get air out of the system. I have four zones, and I have four red valves around my basement that are all on the return line back to the boiler. One is easy to get to, and I've opened that valve much sputtering and spitting as air was released, along with water. The pressure would drop down, I'd force cold water into the system to bring the pressure up, but that wouldn't get all the air out.

Someone said I'd have to do that draining technique on each individual zone, not just the one valve I have 'easy access to". Another suggested I look at my baseboard heating and see if those have their own pressure-release valves on them. To turn off the furnace, let the lines cool a little bit, and then open those valves to let out air. When only water comes out, tighten them down.

Of coures I'm scared that these valves have never been bled before, and as soon as I try to open one its going to snap off in my hand or if its a screw be rusted shut, or break and send gallons of water spilling all over my floor.

I'm perplexed. What can I do here? Whats the right thing to do....any advice appreciated. Thanks in Advance.
Old 02-25-05, 10:33 AM
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Air in Hydronic System


You should be able to tackle this if you've already bled one of the zones with one of the red valve handles; this is known as a "purge valve"; the procedure is to temporarily turn off the boiler elec switch & work on one zone at
a time by attaching a short length of garden hose into a bucket; manually open the zone valve lever for that pipe section by pulling down the little metal-colored lever at the top of the Taco valve (this will manually open that zone) open the red purge valve & use the "quick fill" lever on the auto fill valve to force water thru the zone until the bubbles stop coming out of the hose in the bucket; close that particular purge valve & return the Taco lever to its UP (NORMAL) position; repeat the process for the remainder of the zones; this will get rid of much of the air; you will have to bleed the baseboard/radiators upstairs to get the rest of it.

Next, go to Home Depot or Lowe's & buy 2 extra bleed valves in the plumbing dept.; these come in standard 3/8" compression (screw on) fittings & cost only ~$1 each; if you run into a problem
with any of the valves you can simply unscrew the old valve at the base with a pliers or small 3/8" open end wrench & install a new one; stuff a wad of paper toweling around the valve to catch any water & remove the metal baseboard covers to give yourself room; the water is only at 12 psi, so it is easy to stop with your finger or thumb while you locate the spare bleed valve & screw it in; bleed all the valves on all the baseboard until you get water from each one; this will get most of the air out of the piping system; however, whenever you introduce new water into the system, it has a lot of dissolved air in it; as the water heats up, this air will separate from the water & you'll have to bleed the baseboard/radiators several days later; there should also be an automatic bleed valve somewhere near the boiler/air scoop/expansion tank with a little screw on cap that you can manipulate when the boiler is running to see if any air comes out.

Don't forget to return the zone valve levers back to the UP (non-manual) position & turn the boiler back on.
Old 02-25-05, 07:27 PM
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Danger !!!!

Please get a pro in to check your system IMMEDIATELY . You should never shut the water off to a boiler while it is in operation. It sounds as though you need a new water pressure regulator. If the system loses water and cannot replace it automatically you could easily crack and ruin a good unit. Even worse it may form steam pockets resulting in burst pipes and scalding steam. Excessive air in a system is a good indication of a water leak . It may well be small but over a little time it will result in too much make up water entering the system resulting in excess air. This is likely to be a relatively minor repair and not terribly expensive. If there is no leak in the system then the instalation of additional auto air vents ( the thing with the little red cap most likely) will help to solve your problem. There should also be an air purger ( different peice of equipment ) in the outgoing main supply line. If there is not then ask about having one installed. These are not expensive things to do but failing to properly fix this system may result in having to replace your boiler or worse. Major bucks. $$$$$$$$

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