Bleeding air out of system

Larry Chappa

I have a 3zone hot water system in a 2 level house.Dont know the proper way to bleed off the air.Should the system be hot and the water circulating and do I close off the in and out valves on the furnace?There are drain valves above each zone valve and bleeder valves on the baseboards.Any ideas on this procedure?

Timco

The idea is to get the water pressure up, and scoot the air out with the water. Cold boiler. Pressure up to 25 or so. Close the valves just past the drain cock on the returns, leave the supply open. Turn on water feed, and open drain valve with hose attatched. You will hear the water and air rush out. When the crackeling of the air stops, and you just hear running water, stop. You can close the drain valve and bump up the pressure and open it again to keep the mass moving. Again, get the zone to circulate with water pressure. When done, re-fill to 12# or so.

T

Brad White_9

What

Tim proposes is correct and is called "purging". You should also know that this gets the bulk of free air out but not all of it by any means. Once you fire the boiler to temperature a few times, an amount equal to about 20% or more of the air you got out the first pass will be forced out of solution and will come to rest at the top of your system (high points not just the very top). If you do not have vents, you may want to invest in a Spirovent (microbubble resorber is the generic term). Even just to SHOW it to people...


Seriously, it literally acts like a scrub brush to remove bubbles other air eliminators leave behind.

Pipe it in-line upstream of your circulator. There is a connection for the expansion tank in this device too.