I am getting my ground source geo system up and running. I have three circuits on one manifold that must have lots of air that won't come out. These are upstairs and the 3/4" supply and return are free of air but I can't get circulation through the circuits. Any tricks to doing it? My geo buddy says he can hook up a higher pressure pump, but I don't want to bother him and I want to know all I can about the system.

City pressure and isolation.

shut off one loop at a time.... use a hose... we remove the 30# relief, instead of running pressure at 15# and put a 50# in and run at 25-35# to keep air out long term for stuff on 2 and 3rd floors... If you have trouble getting air out, i would be concerned with the commissioning of the rest of the system?

The one thing that bugs me is when a manifold is placed in the basement and the lines go up to the 2nd or 3rd floors. That is just being cheap. Manifolds belong on the floor that they serve. Then air extraction is easy.

Where the manifold is place has little to do with entrained air. In my own recent remodel I installed one manifold in the basement for 3 floors. All controls and a circulator on one wall, one location.

Posted By MikeSolar on 06 Mar 2013 06:59 AM
The one thing that bugs me is when a manifold is placed in the basement and the lines go up to the 2nd or 3rd floors. That is just being cheap. Manifolds belong on the floor that they serve. Then air extraction is easy.

I agree, It also keep the mech room from looking like a mess a of twisted pipes

In theory, one should be able to extract almost all the air by pulling a vacuum on the entire circuit before filling it with water.

Why should anyone have to go to such lengths as a vacuum to remove air from a system? Entrained air is not a problem when the manifold is above the loops and initial filling is still much easier. I have been to many, many houses to get air out of system with all manifolds in the basement. It is logical to have air elimination at the highest point and has been since day one of hydronics.

I have many hundreds of systems in operation with manifolds upside down and/or in the basement, with air elimination in the basement as well. typically it's more waste pipe than makes sense to keep the manifold in the mech room, but not always. And with those loops, we ignore reynolds numbers too and run super low flow rates! It's amazing, they shouldn't ever work.

but they do. air entrainment is not a problem if you don't have leaks, operate at appropriate pressure, and use a good quality air elimination device. where in the system should it be? doesn't matter. Where should the manifolds be? doesn't matter. the INITIAL fill might take a little more isolation and purging, but that TYPICALLY isn't a very important design consideration. and I would say in fact it may take less time in some cases, because you don't have to run all over the house to check flow rates when you're balancing and inspecting for flow.

manifold placement has nothing to do with air. not in a good system.

Mike - logical but not always possible.

I have always been able to put manifolds on each floor so I cannot see an issue there. Flow rates have never been a problem and entrained air is not a problem the way i do it but like I said, with low flow rates and 20ft verticals, over time a bubble COULD form that reduces or stops flow to a loop. I have taken the air out, put in spirovents bla bla bla, but I prefer to avoid the problem in the first place. If you guys don't have the problem, then kudos to you.

I have clients that dont want fittings anywhere but the mech room to keep down on leaks and they also don't want service being done in their living room, its understandable. I always put a spirovent on the supply line on my secondary loop when I can't do a true highpoint vent. I agree that having a vent at the high point should always be your first choice. However I think the OP was looking for the best ways to clear air when you don't have that option. Personally I use a 30 gallon Polyprop jug and a gearpump combined with two sprirovent I've picked up from scraping other jobs over the years. this works amazingly well.

they also don't want service being done in their living room,

How much service needs to be done on manifolds? That makes me nervous. I put all my manifolds in walls behind built-in cabinets. Just take off the panel in the back of the cabinet for manifold adjustment.... Is service more extensive than that?

Its more about, if you have to come back for what ever reason and you need to work on the manifold again the risk of fluid spilling out and causing more damage is what they are worried about

Oh. I've got water in there.

Can't say that I have had any leaks on manifolds especially Rehau or equivalent quality so it has never been a problem and I valve things off in the mech room anyway so that it can be drained from there in isolation. Other than a little spittle coming from the manifold air vent when filling, there shouldn't be an issue with water.

The OP needs to get the air out. First the loop pump and isolation of the rest of the loops and if that is not enough, city pressure.