HELP! How to purge air from basement loop?

Johnny12

I had a pipe burst in one of two hot water loops in my basement zone, and repaired the burst section of pipe myself. Now, I'm having a hard time getting the air out of the loop.

I made sure the upstairs zone wasn't calling for heat so that the zone valve on the return for the upstairs was closed. Then, I turned up the thermostat for the basement zone and ran the system with cool water (I have the boiler off so it doesn't fire). When I did this, I didn't hear any water moving through the basement loop, although I did hear water noise at the circulator. I never heard any gurgling noises like I would have expected, either. I really think that there's still a slug of air stuck in the basement loop and I didn't accomplish anything.

I want to note that I did not close any of the valves on the supply side when I did this. Is that possibly the problem?

RJ_4

air

Always shut the pump off when bleeding air from any HW baseboard or terminal unit. If you dont have a purge valve ahead of the return shut off valve you will need to install one. Until you have time to make permanent repairs you can install a saddle tap on the baseboard piping, The type used for tapping into water lines to hook up ice machines on refrigerators.

Johnny12

Purging air from a baseboard loop

I don't have any purge or shut-off valves on the return side. I only have the zone valves on the return plumbing near the boiler, and a drain directly underneath the circulator pump.

I took another look at the system, and I think I might be able to do what you're describing in the reverse direction, though. I have shut-off valves in between the cold water feed and the supply side going to the expansion tank and the baseboards. So, if I close those valves and manually open the zone control valve, I can block the flow of cold water so that it is forced backwards through the boiler and the baseboards, and then open up the drain valve on the supply side until the air is purged.

Does this sound like it will work, or is there a check valve somewhere that will prevent this from working?

Johnny12

Another question related to purging this air...

One more question related to purging the air out of this loop. I can either put softened water or 20-grain-hard water back into the system. Which would be better?