air in copper HW heating lines

[FINER9998]

i helped a friend install an intellidyne HW+ boiler control.http://intellidynellc.com/ all went well and the boiler fired properly and the control is functioning as it should. however, when the bolier was fired, we noticed the system's single circulator was sucking air when a basement zone called for heat. home has 6 zones, one for indirect HW heater and five heating zones(copper HW baseboard). we bled the offending zone and immediately got heat. system is functioning properly as of 10 pm sunday night. my question is, how could this zone become air bound? there are no noticeable leaks anywhere and the boiler was not drained as part of the boiler control installation. its as though some of the water in this one zone, which wasn't used much in the last month, "magically" evaporated from the heating pipes. i know this sounds ridiculous but it happened. any thoughts on how the air could have gotten introduced into only one zone of the system?

[Masterplumb]

Is the Circulator installed on the return or supply?

[mtnman1100]

when you add more water to the system you are adding more air also. When the water is heated it releases the air that's why you need a scoop with an air vent on top, preferably on top of your expansion tank at the point of no pressure change, then the primary pump pumping away from there.

[mtnman1100]

http://www.nextstepenergy.com/images/boiler_heating.gif (http://www.nextstepenergy.com/images/boiler_heating.gifI)
check out this diagram

[Masterplumb]

when you add more water to the system you are adding more air also. When the water is heated it releases the air that's why you need a scoop with an air vent on top, preferably on top of your expansion tank at the point of no pressure change, then the primary pump pumping away from there.

He stated that he did not drain the system or that there is no leaks, so I take that as no new water was added. I never install an air scoop on any systems I install as an air scoop is basically useless. The only time I'll add an air removal device is when its for a radiant zone, and I'll use a spirovent.

[plumberscrack]

He stated that he did not drain the system or that there is no leaks, so I take that as no new water was added. I never install an air scoop on any systems I install as an air scoop is basically useless. The only time I'll add an air removal device is when its for a radiant zone, and I'll use a spirovent.

I agree, the air scoop is a waste of time. I'll put in a spirovent when there is a radiant zone or fintube baseboard.

[bigPipe09]

mmmm Microbubble resorber...so sweet

[FINER9998]

spirovent atop the expansion tank at end of supply (water going out of boiler up to heating zones) header. single circulator on return side with zone valves also on return side. all heating elements are 3/4" copper fin tube baseboard. the boiler is located in the basement of a ranch style house and the greatest amount of air occurred in one of the two zones that heat the basement. any ideas as to where the air came from?

[Masterplumb]

spirovent atop the expansion tank at end of supply (water going out of boiler up to heating zones) header. single circulator on return side with zone valves also on return side. all heating elements are 3/4" copper fin tube baseboard. the boiler is located in the basement of a ranch style house and the greatest amount of air occurred in one of the two zones that heat the basement. any ideas as to where the air came from?


Who knows where the air came from. The question is if you remove or have removed it, will it/does it come back?

It may be coming from the circulator being on the return pumping towards the point of no pressure change.

What is the systems pressure with the circulator off?

Is the system brand new or has it been operating like this for a long time?

Maybe a few pictures of the boiler and near boiler piping would be helpful.

[plumberscrack]

My guess is he had some work done on the system this past year and drained the boiler. He may have purged the system after filling but like MTMMAN said the air will eventually separate and collect in a high spot. And in this instance, the basement zone.

Unless there is a radiant zone under the floor I wouldn't suspect a leak

Master are you suggesting that the pump is cavitating because it's on the return side?

I like pictures too

[Masterplumb]

Pcrack, Here is what I'm talking about.

http://www.bellgossett.com/Press/CounterpointJan2001-A.pdf