Help! Getting the Air Out

[velvetfoot]

I'm having trouble getting the air out of my system. I'm sure things aren't ideal for doing this. High on the list is no vents on the distribution piping. I guess that's the trend nowadays-all the original system had and has is a Taco air scoop. This air scoop is on the supply header, but AFTER the thermomix valve. The supply header then goes to the distribution zones and then to the buffer tank. There are air vents (Hy Vents) on the air scoop and on top of the buffer tank.

It'll be tough to dig around and try to sweat in air vents in the distribution piping.

I guess I could put another air separator (non-air scoop) after the tank and before the supply header.

I'm visualizing big bubbles of air that won't come down easily. They float up and there are no vents there. Maybe I'm visualizing wrong.

There are drain valves on the supply side of the return-pumping distribution pumps that I tried bleeding from this morning, zone by zone, using the fill valve, but I don't think it did much good.

I'm hoping that over time the bubbles might travel to the air scoop vent and tank vent, but I don't know.

Is there no substitute for having valves at the high points?

I don't want to mess up my nice new pumps; they're sounding quite gravely.

Thanks for any tips.

 

[brant2000]

I think bubbles will take care of themselves without any trouble. I tend to notice a few random puffs of air releasing out of my air scoop vent for the first few hours of starting up, after the system has been open. I think dissolved O2 will continue to vent off as you bring your temps up. The key is just to make sure that you don't have any large air pockets or sections of piping that would cause a circulator to lose prime. Small pockets/bubbles of air will continue to circulate around until they find their way out the vent.

 

[velvetfoot]

That was my original thought, but I don't know, these might be pretty big bubbles. I'd feel better with some vents off the baseboard, just that the potential for failure in adding them to the baseboard is great, for me, anyway. I think I'll search for and maybe resurrect an old thread on the subject.

 

[Bob Rohr]

That was my original thought, but I don't know, these might be pretty big bubbles. I'd feel better with some vents off the baseboard, just that the potential for failure in adding them to the baseboard is great, for me, anyway. I think I'll search for and maybe resurrect an old thread on the subject.

Big air you should be able to purge out with the system fill pressure and valves placed in appropriate locations.

The pump circulating the system will eventually take care of the small and micro bubbles.

If you have a zone or section that is not circulating, you need to power purge it. Crank the fill valve to 25 lbs to help get a good clean purge and isolate zones to purge one at a time to get a good flow rate.

I prefer microbubble type separators, they work quickly and remove the smallest of micro bubbles better than a scoop.

High point vents can help catch air that may rise over the off season, but really are not needed if you have a good central air eliminator and flow in all the zones.

Vents in finished living spaces tend to leak more often than the ones in the un-finished basement

 

[velvetfoot]

I'm getting flow, but darn noisy, and you can hear bubbling. I might try fast flow purging again.

 

[Bob Rohr]

I'm getting flow, but darn noisy, and you can hear bubbling. I might try fast flow purging again.

If you have enough isolation valves, purge one section at a time, valve it off and go to the next. It's tough to purge an entire system at one time from one point. You end up just chasing the air through all the piping.

The scoop vents, with that tiny 1/8" air vent can take hours, or days to get the system air free. And they don't work well if you are flowing through them quickly, below 4 fps is their comfort range, else the air flows right on by that vent hole.

 

[velvetfoot]

Thanks. I tried a lot just now on the distribution, but kept on getting that noise that I thought was bubbles on the hose I strung to the outside. I kept the boilers out of it, but there's probably air somewhere in there as well or the headers or tank or something. I turned the system back on, and even without the distribution pumps on, I can hear the air bubbling up through the pipes-not a good sign. Maybe I'll stay up 'til it's warm enough to run, but I bet they'll be some more interesting noises when they do. After all that running of the makeup water through the distribution system and out through the fill valve by the pump, I don't think I've made any progress.

 

[mike van]

I had the same problem, and to make it worse I found my 40+ year old 'keep full' valve on the oil boiler was rusted inside beyond a useful state. Like Bob said, try to do it in sections, that worked best for me, sometimes the valve I opened would run full bore [after I changed the rusted up 'keep full' valve], for maybe 2 gallons of water then a big belch of air would come out. I put one of those air scoops on a 6" long 1/2" pipe tee, just to give a little better trap for the air as it went past. I thought I'd have to cut one into my upstairs heat loop too, but eventually got the air out without doing that.

 

[velvetfoot]

I spent all morning futzing with it and think I have it pretty good now. But it is cold, so we'll see when after it gets hot.
I have the two Vario zone pumps running at max, and also the pellet and oil boiler pumps, also Varios running at max as well, and no noise, knock on wood.
The only noise appears to be coming from the Caleffi Thermomix. I wonder if a check valve could be the culprit there. Maybe it'll go away when I turn things down.

It's all well and good to do the zones separately, but they are all ultimately connected to the headers.
The Thermomix also complicates things somewhat because there's no flow on the return below 130.

Anyway, I would definitely valve everything off that I could to avoid going through that again, not that I'm declaring victory yet.

I wasn't able to do a fast flush with the boilers in the loop because my Watts valve only had a fast fill lever, and it's not adjustable, and the pressure relief valve would (and did, lol) if the pressure gets over 30 psi.

If I did it over again, for my particular setup, maybe it would go like this:
-Start from bottom and go up
-Isolate everything not being bled
-Boilers
-Tank (if >130)
-Fast purge zones individually
-Open isolation valves to boilers
-Using autofill pressure, repeat!
-Open tank valves, zone valves one by one, bleeding more
-I found that running the zone pump, then turning it off and bleeding helped, but oh so tedious.

That's all I got.

I'd definitely like tomake it easier. If it doesn't hold the purge, I'll be looking into a different air separator, but space is tight.
I can see the point in not having vents in the living area for the dripps, but I still might check it out. I don't think it would be that easy to break up the exisiting connection and sweat in a connection in the baseboard locations.

 

[velvetfoot]

More noise, even when cold. It might be a long haul.

 

[velvetfoot]

To close the loop, as noted on another thread involving automatic air vents:
I added a Spirovent at the supply pipe of the tank, bumped up the cold system pressure to 15 psi, and run the pumps on low (for now). Totally silent. I give most of the credit to the Spirovent.