b&g in line air seperator install question


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Old 01-14-11, 07:52 PM
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b&g in line air seperator install question

I am wondering about installing this air separator. I am wondering about the orientation of it. There is an up arrow on the unit, that points to a small fitting for a bleeder. The bottom fitting, is a larger fittings, that would connect to an expansion tank. Is it ok to have this larger fitting pointing up to a conventional expansion tank?
 
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Old 01-14-11, 08:22 PM
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It's been a while since I looked at those, but I do recall that some models have the 3/4" tapping on the top for a conventional tank, while others have the 1/8 for the air vent.

I doubt that they will operate properly upside down.

I just looked them up at

Inline Air Separator - Bell & Gossett world leader in supplying the Heating/Ventilating/Air Conditioning (HVAC) industry.

If you want one to use for a conventional tank, you would have to go to the 1-1/2" size and bush down the inlet/outlet for the size pipe you are using.
 
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Old 01-15-11, 06:23 AM
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You don't think rotating it would work? I looked inside the unit, and It is hollow inside. The only thing that is in it, is on the output end, it is internally necked down. So the air will be stopped by the dam inside it.
 
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Old 01-15-11, 06:56 AM
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I've never looked inside one... but I don't think I would try to second guess the manufacturer.

How big is the 'boss' where the 1/8 tapping is? Maybe a local machine shop can drill and tap for 3/4 NPT ?
 
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Old 01-15-11, 07:18 AM
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if you are going to seriously install one of these, why not spend the little extra to put a new bladder style exp. tank in? you dont have to mess with bleeding the tank or any of the bs you had to with the old style tanks
 
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Old 01-15-11, 07:50 AM
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How big is the 'boss' where the 1/8 tapping is?
The "boss" in which you are referencing, is all of 1". I have not exactly measured this, but I am very confident that a 3/4" hole could be drilled and tapped here. This was one of my initial thoughts as well. Secondly,
you dont have to mess with bleeding the tank or any of the bs you had to with the old style tanks
I cannot say that I have ever had to do much with this. I have an airtrol tank fitting on the tank. In regards to the tank, I drain it off, open the airtrol, let the air go into the tank to charge the tank, then open the control valve for the tank, and refill the system up to proper pressure. Perhaps I am not doing this right??? But, I can say that I have not had much issue with the old tank. Any input would be appreciated.
 
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Old 01-15-11, 08:58 AM
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you are doing it right, but with a bladder exp tank you simply screw it in on the bottom of the air purger and you are done.
 
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Old 01-15-11, 09:36 AM
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correct. But, according to the book, then the top hole is for a float type air bleeder. I did do some looking around, and I have a 1/2" tap. Would I be able to tap this hole out to 1/2" then run a 1/2" thread to 3/4" sweat adapter on this to make it work?....
 
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Old 01-15-11, 10:03 AM
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I'm not sure we are talking about the same thing. do you have a part number? I was talking about something similar to this which is an Air Purger Put an air vent on the top and a bladder tank on the bottom. This system is what I use when installing new boilers in my area.
 
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Old 01-15-11, 10:09 AM
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to clear anything up, i am using this, as it was also designed to work on a conventional tank system. Sorry for any confusion. The generic manual for this piece is here, which will show a diagram with this air eliminator in a conventional tank application.
 
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Old 01-15-11, 10:24 AM
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that manual is crazy confusing. What size of fpt is currently on the top of the unit? is it 1/8"? if so their install diagrams make no sense as to how they connected your type of system. I would go to a boiler supply house and ask them what to do in the situation, because I would not change it to something that the manufacturer did no mean for it to be used. I know the instructions show the way you are talking about, it does not tell how they got to that point using the type of unit you purchased.
 
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Old 01-15-11, 10:37 AM
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well, according to their website, or if you look further down in this thread, if you get the 1 1/2" unit, the top hole is 3/4", specifically designed for this application. The parts house that I ordered this from neglected to give the hole sizes for the top and bottom holes. But, this would mean i would have to get the 1 1/2" unit, use bushings to get down to the 1 1/4" that I need, and that unit is roughly 10-15 bucks more, since the hole sizes are larger.
 
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Old 01-15-11, 11:35 AM
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Part of the confusion comes from the fact that B&G seems to have done a not so stellar job of updating their literature.

Years ago ALL sizes of the IAS had the 3/4" tapping in the top. Perhaps because they wanted to keep a share of the market, and most residential systems being installed were using bladder tanks, they changed the two smaller size IAS to a 1/8" tapping on top to accommodate the float type vents.

AFAIK the bottom tapping has always been 1/2"... and when installed with a steel compression tank would have been used for the water feed to the system. It just happens that 1/2" is also the size needed for hanging a bladder tank from.
 
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Old 01-15-11, 01:05 PM
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or would it be a simpler option to just exchange for the correct unit, with the 3/4" hole in the top?.....
 
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Old 01-15-11, 03:07 PM
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Perhaps... I guess it might depend on what a machine shop would charge you to modify that one... probably more than the extra cost, and then dont forget that you will need bushings or reducing couplings to go back down to 1-1/4 ... might end up being a 'wash'...

If you DO go the modification route, make sure they understand that you want NPT threads!
 
 

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