Purging Air Mystery

dooododoo

Okay experts, I have something that's been puzzling me. Consider the diagram below.



Is the correct way to purge the lines to:

1) close the SO below the circulator
3) close each return SO
2) connect a hose to the drain above the circulator
3) open said drain, and
4) purge each return line?

rick in Alaska

Pretty much, yes. Probably go through each one individually, then do it again just to make sure. Make sure you don't pressurize too much or you will blow the relief valve.
Rick

delta T

Yes.

If you have zone valves, make sure they are locked manually open for the zone you want to purge, and of course turn the boiler off as step '0'.

Purge until you get clean, airless water (within reason, you will never get every last bit of air out) and then allow the air separator to remove the remaining air. You do have an air separator installed right?

dooododoo

Is it this?

delta T

That is an air vent on the boiler, not really a proper air separator. Stand back and take a picture of the boiler and the piping around it.

Are you having air problems?

dooododoo

In that case, I don't have an air separator. I've had to purge one zone twice in the past 4 weeks. I discovered that I need a new expansion tank. Ill see if that fixes the problem.

Can't take a photo right now. Apartment is all the way in the city.

dooododoo

delta T said:

Are you having air problems?

No, I don't have an air separator. However, I was having air problems. One of the zones kept getting cold. Turns out the bladder on the expansion tank failed. Replaced and system runs like a champ.