Air in baseboard heating system

[shrewsky]

Hi, Thanks in advance for your help.

Early this summer the boiler valve was opened during repair to the cold water feed to the hot water system introducing air into the system (please, don't ask). Now, of course, the pipes are gurgling. There is a Watts air scoop with an air vent which doesn't appear to be venting any air when the system is on. I had been hoping this would solve the problem.

I know the basics to bleeding the system from reading various forums but I have read some conflicting steps that I'm hoping you can clarify.

First some basics on my system with pictures:
Burnham propane system
2 zones in a raised ranch with 1 zone for up and 1 for down
Zone upstairs heats with noise
Downstairs has no heat
There are no vents at the baseboards







Now for my questions:
1. I've read to bleed each zone separately. Attach a hose to the valve of the zone being bled and put the end into a bucket to monitor air removal.
Close the corresponding yellow handle below the blue valve
Open the blue valve
Open the water feed (some include this step, some don't)
Drain until no bubbles are seen in the bucket
Turn off the blue valve
Close the water feed
Open the yellow handle
Repeat with the other zone
Can you verify these steps are correct and in the right order?

2. I read in one forum that I need to isolate the zone I am purging. Is that what I am doing by closing the yellow handle? I am confused because the 2 zones spit from a central lead from the furnace on the supply side so they are always connected to each other. How do I stop air from one zone from being introduced to the zone I am bleeding?

3. Should the heat be on or off? I've read both. I've also read that the heat should be turned on to heat the system and then off prior to starting to bleed.

4. With air having been introduced at the boiler, will bleeding the system work?

I'm out of work and this seems like a simple process so I'm hoping to avoid a service call.

Thanks again!

[beenthere]

That is pertty much it.

Boiler off, exspecially since your autofeed will be putting cold water into boiler.

A bucket may not be big enough, might want to use the sump, if you have one.

Also thats not a proper thimble for your vent system.

[karsthuntr]

I use a utility pump to recirculate the water through the boiler, it beats hualing buckets and doesn't waste water.

[casturbo]

That vent you have is nothing special, and after awhile they hardly work. If they don't leak, and remove some air, that's all you can expect. A true air separator is much more complicated, and really not necessary if a system is purged correctly. Your purging procedure, as described, is just fine.

[shrewsky]

It went very smoothly. I now have heat in both zones and it is quiet!

Thank you very much!