OWB install, purging air from lines

[Slick]

I'm using both outputs on my CB 5036, one to shop is up and running, hopefully house this weekend, both setups use water to air exchangers. Shop hanging heater is highest point in system, boiler drain on top seems to purge out air easy enough. First question...should I have to keep purging air out of that? It's only been running a week but seems like every day I can purge out a bit of air, is that normal? I don't have any leaks that I can find but it seems to me I shouldn't keep getting air, maybe I just don't have it all yet?

Second question is the house....the lines to the house a bit different that most...goes into my shop, up about 14ft, across a 40ft I-beam, down 14 feet again then out the building and underground 100ft to house....inside the house my side arm exchanger will be the highest point but the 14ft up and over the Ibeam is technically the highest point in the system but it's a seamless run of pex up and over the shop...my question is purging air....after hooking up my shop I know I'll have air to purge...but where? Top of side arm? That would be easiest but my fear is air will end up in the shop over my Ibeam 14ft up...will I even know it's trapped? I could put a T up there with a vertical stub and boiler drain but I'd rather not...that would certainly be highest point though....even then which line needs it, both or will it make it's way to which ever line has the T and stub? My furnace water to air coil is lower than my side arm...shouldn't be any need to purge there correct?
Maybe I'm overthinking and should just hook it up?

 

[Laird]

I'm no expert on the subject, having just finished my own OWB install last weekend. As I understand it, the water driven by the pump will push any air through your pipes till it enters the boiler tank that is vented to the outside air. I have a filter system on mine that has a clear filter holder on it that keeps debris from lodging itself in the HX's. For the first 24 Hrs I saw air bubbles spinning around inside, but after that amount of time they went away. But that was on the output side about 50' from the bump. I was instructed to run my pump for the first 24 hrs w/o firing up the boiler.

Personally I don't think I would worry about it unless a problem presents itself.

 

[blakey]

I have a similar setup but ran a separate loop for the house. I had a heck of a time getting the water to flow in the shop loop, my hx is up about 10ft in the air. Your water temp may be a little low by the time it gets to the house if you are running everything on one loop ( I wasn't sure from your post) When I shut mine down in the spring I have to remember to close the valves on the shop loop or it will drain back to the boiler and I will have to bleed the lines. Otherwise I never have to bleed the lines anymore.

 

[Slick]

Yeah sorry I wasn't more clear, completely seperate loops, two pumps...009 to the shop is running now...0013 to the house only thing house and shop have in common is the boiler itself.
If I didn't have the boiler drain on the hanging heater exchanger right now I woudln't have known I had air in there....cracked it to see and yep air came out, still makes heat fine but day after day I get some more. I did notice the lines are quieter now, a bit of water rushing noise at first which I assume was the air bubbles flowing around, wondering if it's going to keep showing up at the exchanger...

 

[blakey]

If it is flowing and getting good heat you are fine. I think part of my problem is that my pump is a bit undersized. I only have an 007 on that loop and it actually feeds 2 small buildings.

 

[Slick]

Ouch, and 007 doesn't have much oomph I didn't want to go up to the 0013 but I used the head calulator on the Taco's site and I need the big 0013....even my shop needed a 009 and my exchangers are not that far away from the OWB...it's amazing when you look at the numbers how much more heat you get from more gpm of the large pumps...and how much head builds up using fittings etc.

 

[mtfallsmikey]

What do you have for a bleed fitting at the highest point? I wound up with junk radiator/BB bleeders that leaked air...check for leaks at the high point first. Did you use check valves on the returns as CB recommends? Remember, head is not only the altitude which the pump will lift, but also the resistance of pipe/fittings, HX's, etc. for piping, figure 6' head/100 ft. of pipe.

 

[ericjeeper]

Taco makes several

Air scrubbers. But the air should eventually settle out of system. (well actually float out)
I used several of the mini vents on my wood and solar setups.. less than 10 bucks a piece. Has a float in there and a small brass valve on top.

 

[Slick]

Yes I have check valves. Bleeder up top is a boiler drain. I calculated head from the full equation on the Taco website which figured in type of pipe, fittings etc...altitude actually doesn't figure into it at all using that equation, the tech guy told me actual height doesn't matter as the water is coming back down the other side basically pulling like a siphon.
I have two exchangers running in parallel, someone mentioned in another thread to turn one off to get max flow to the highest exchanger which is a good idea, I'll try that tonight.

Eric I'll have to check out the air scrubbers, thanks.

Still not sure if I need a bleeder in my lines over the shop to the house....sounds like everyone gets air trapped in the exchangers but my lines will be higher than my exchanger??

 

[i'mstihlaguy]

Yes I have check valves. Bleeder up top is a boiler drain. I calculated head from the full equation on the Taco website which figured in type of pipe, fittings etc...altitude actually doesn't figure into it at all using that equation, the tech guy told me actual height doesn't matter as the water is coming back down the other side basically pulling like a siphon.
I have two exchangers running in parallel, someone mentioned in another thread to turn one off to get max flow to the highest exchanger which is a good idea, I'll try that tonight.

Eric I'll have to check out the air scrubbers, thanks.

Still not sure if I need a bleeder in my lines over the shop to the house....sounds like everyone gets air trapped in the exchangers but my lines will be higher than my exchanger??

If I understood the description from your first post correctly, then you have a 40 ft run along an I-beam 14 ft above the rest of the system. The water flowing through that section could be occupying to bottom half of the pipe and the air staying there but entering the rest of the system sporadically when/ if a surge occurs. I was told to definately install bleeders in all high points. I am no expert, just trying to look at all the angles.

 

[Slick]

Yeah that's what I was thinking...if that pipe in the I-beam has some air in it....no way to get it out and it is the highest point....crap, didn't really want to crack into that pipe but maybe I should...what do you think, put a T in with an extension going straight up? Boiler drain up there or is there something easier/cheaper? I'd love to see something I could crimp right onto pex....

Had a weird discovery tonight...after the talk of series parallel differences in other threads I closed the valve on my lower heat exchanger to force all the flow to my upper exchanger, thinking it would force any air out that I had in there (been getting a little bit out everyday for a week)....when I sent all flow through the exchanger I turned the boiler drain a bit and tons of air was heard gurgling....but it never stopped..., was freaking me out a bit so I shut it and went down to where they are paralleled...I could hear the water heading down the pipe back to the boiler, definetly coming down towards me (pipes go straigh up to exchanging hanging from ceiling)...I think with all that flow I was pulling air into the system insted of purging it out...never would have thought that would happen....

 

[urhstry]

What kind of bleeders should be used? Anybody got pics?

 

[Slick]

Here's how I have my boiler drain. I made this hanging heater and it's the highest point in my system, my Central Boiler guy said to put a boiler drain up here. It does purge out air but like I said earlier, just keeps coming back every day.

Also next to the hanging heater is my I-beam with the lines going to my house (both lines enter the building below that hanging heater in my compressor room). The highest point is right where that vertical piece of white foam is ....thinking I need to cut that pipe, put a T in with some kind of air release.
Who wants to guess how much fun it was to uncoil and run two lines of 1" pex along that I-beam while on that extension ladder? :censored:

 

[mtfallsmikey]

Try a threaded garden hose cap on that boiler drain, make sure packing nut is tite.

 

[Slick]

You mean to keep it from leaking? I figured the boiler drain was air tight...crap..

 

[mtfallsmikey]

Yes!...I would NOT put any float-type, or coin-vent type fittings on an open, non-pressurized system. Air is sneaky. Try the cap on the B. drain valve.

 

[tawilson]

You could put a elbow on the boiler drain to put it verticle, pointing up. Maybe even a short nipple on it so it traps more air.

 

[ktm rider]

Why not just us a automatic air vent? Problem solved.

 

[Slick]

Yes!...I would NOT put any float-type, or coin-vent type fittings on an open, non-pressurized system. Air is sneaky. Try the cap on the B. drain valve.

Hmmm....I just bought some coin-vents for the over head run I was talking about...why are they a problem with open systems? I was going to get the automatic vents like KTM just linked..but I cheaped out This install is really adding up on me....

Actually over night I realized I have few more fittings to deal with to get my coin vents to work....might just use two boiler drains up there instead....I have two of those Acetate (spelling?) plastic like boiler drains sitting here I ordered by mistake.....they are rated to handle the heat no problem...something about using plastic seems weird to me Anyone use them? I didn't want to use them on my exchangers, might be screwing a hose on there or something but these are just for purging air...

 

[mtfallsmikey]

Well, call me anal, but....I had problems with coin-type vents leaking, were purchased from HVAC wholesaler...made by Ching Chong. The schrader valve in the float-type can cause problems too. At high points in a non-perssurized system, pressure is low..water flow can cause a type of venturi effect, if a vent or fitting has a leak of any kind, it may not leak water out, but can draw air in....I've only been fooling around with hydronics for 40 years, don't know much.....stay away from plastic drain valves also.