Airlock in baseboard heating system! Help!!


Old 03-05-17, 11:31 AM
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Airlock in baseboard heating system! Help!!

I noticed last night (5 degrees outside) that the first floor was not keeping up with the heat.

My house has 3 heating zones off of a water boiler. Each floor has baseboard pipes with fins against the walls.

I noticed the 2nd and 3rd floors were heating fine. The first floor was cold.

I took apart the motorized 3 way valve and found it to be working fine.

I opened the drain for the 1st floor system and turned on the valve for the water feed and water was flowing through the three way valve to the drain without a problem.

When I seal off just the first floor, no water is coming through the drain.

So this brings me to 2 questions:

#1) How to bleed the air? Most sites indicate I should go to the highest point and open an air valve, but I have a sealed copper pipe system. I do have a small tire valve above the furnace which I expect is for removing smaller air bubbles from the system. When I press that in, I get hot water, not air. I tried holding it for 20 seconds and nothing but hot water.

#2) I assume getting an a big airpocket like this is not normal and indicates a leak in the system? I don't see any leaks anywhere. How do I diagnose this? I guess it's possible that I caused a smaller air pocket to be bigger by messing around with the drain and the valve to begin with.

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Old 03-05-17, 12:46 PM
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To bleed your system you must isolate the zone you want to bleed which means valve off the other 2 zones so that know additional water can be introduced into those zones.

Next, lift the lever of your feed valve if possible and bring pressure to at least 25 psi or so making sure to stay under 30. With the pressure up and the feed valve open, open up the spigot on the return line for that zone and let water run until all the air is out and you get a nice stream of water out.

When you're satisfied there is no more air close the spigot and put the feeder back on automatic. At this point you will most likely have high pressure in the boiler which is what you want so no fresh water gets introduced after the zone is bled. Drain excess water from boiler to bring pressure down to about 18 psi.

Once this is done. make sure all isolation valves are open to system and turn on boiler to restore heat.

This is all done with the boiler off of course and if you have zone valves the zone you are bleeding must have the zone valve opened manually to allow water to flow through.

I did pick up something from your post about when you isolated the first floor no water came out of spigot. You might not be air bound at all but are experiencing frozen pipes.

If you start your bleeding procedure and nothing comes out shut your spigot and open all your valves on the other zones back up, restore proper pressure if high and restore heat. Look for frozen pipe or you can manually open that zone valve to the frozen zone and whenever any other zone calls, water will also flow through that zone eventually thawing it out.

Keep an eye out if it is frozen that when it thaws the pipe isn't split. It will not show up when frozen until thawed.

Hope this helps a little.

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