b&g inline air separator question

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Old 09-30-11, 07:53 PM
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b&g inline air separator question

I have recently installed a bell and gosset inline air separator. upon installing this unit, i allowed the water to circulate while cold to bleed off any excess air the system may have. I have also bled air from all baseboards in the house as well. Now, I am allowing the boiler to run normally, and it usually cycles once per day in the early morning, which is 3-5 am. everything appears to be in fine working order, but upon my daily inspection of the temp/pressure gauge, I have noticed that the water pressure drops off. I would expect this would be due to the air separator removing air from the system. I have been noticing this happen for the last 2-3 weeks approximately. My question is how long will the unit continue to do this? Is there a point in which all of the air will be removed from the system, and the pressure will stabilize?? Any advice is much appreciated.
 
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Old 09-30-11, 08:05 PM
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you should have a cold water makeup supply that auto refills the system to the correct pressure....
 
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Old 10-01-11, 07:00 AM
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Typically there would be an auto fill as stated before. If you have one, there could be a closed valve on the domestic water supply line preventing it from entering. It shouldn't take very long for the system to equalize pressure. Keep in mind that you should have a minimum of 12 psi when the boiler is cold and that the pressure will rise when it gets hot and go down again when it cools off. The few times I have worked on my system, I like to run the boiler for a little while to help get the air out. If it was aheating zone I drained, then I turn up the thermostat for that zone. If it was just the boiler, I will get the indirect water heater to make a call and run it that way. Heating the water will get the dissolved oxygen to come out of it.
 
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Old 10-01-11, 07:26 AM
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Depending on how much fresh water you've had to add, and the location and efficacy of the air removal devices, it could take quite a while. Weeks? maybe... or there's a small leak somewhere un-noticed.
 
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Old 10-01-11, 09:26 AM
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The unit is installed on the main output of the boiler. The boiler system has a steel expansion tank. So, the top fitting on the air separator feeds to the expansion tank. I do not have an auto filling valve in the system. I am a little apprehensive about adding one of these to the system, as they can actually hide a leak, or make a leak worse. From what I can tell from my observations, the system does not have any noticeable leaks. Upon the system cycling and the COLD pressure being 15psi, it will run, gain pressure and shut down as it should. After cycling, and once the water has returned to cold, the pressure will drop off to 10-12 psi. I have been checking daily, and adding a very small amount of water to maintain the 15psi cold pressure. I have been doing this for 2-3 weeks now, and I do know that some of the baseboards to have some air in them yet, as when I check the bleeders on the baseboards, a small amount of air is relieved. I am just wondering if it is normal for it to take this long to get all air removed from the system. On another note, the boiler was completely drained off in order for the air separator to be installed. I hope this information helps. Thanks.
 
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Old 10-01-11, 01:12 PM
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This is not uncommon especially this time of year. All the cold water as oxygen in it that will need to be removed (H2O-hydrogen & 2 parts oxygen). When heated you will drive the air out of the water, again this may take some time during normal operation.
How much horizontal pipe is before the air separator?
Does the pipe go uphill all the way to the tank?
Any valves in the vertical pipe only?
Piping 3/4" to the air separator?
 
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Old 10-02-11, 05:34 AM
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Here is a picture of the installed air separator. The inlet and outlets of the unit have 1 1/4" pipe, and then, 3/4" pipe runs up to the expansion tank. I had to put a 45 elbow in the line going to the tank, as I was unable to get the airtrol valve to rotate at all, but it is all pitched uphill to the tank. see link below.

Installed air separator

 
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Old 10-02-11, 07:15 AM
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Do I see a bladder-type expansion tank in the background of the photo? I don't think you would want a bladder tank and conventional steel tank on the same system.
 
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Old 10-02-11, 07:31 AM
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That appears to be a potable expansion tank on the hot water heater. Not sure it shoudl mounted upside down like that, though.
 
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Old 10-02-11, 08:09 AM
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I cain't see hardly nuthin in that pic! I don't know why there should be a difference, but well tanks are always with the schrader on top, and almost every potable tank I've seen has been like that too.

I completely understand the reason that the heating tanks should be with Schrader down, and my brainiac tells me that potable tanks should be also... but then, aren't the floor mounted heating expansion tanks mounted Schrader up? ahhh who knows,,,, long as it works!
 
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Old 10-02-11, 08:47 AM
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yes, the tank in the background is for the water heater. I did not install that tank. In the front of the photo, the 3/4" pipe with the 45 elbow in it leads to the steel expansion tank, which is not pictured.
 
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Old 10-02-11, 04:19 PM
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That looks like a stop & waste in the horizontal pipe. Should be a full port ball valve.
 
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Old 10-04-11, 05:10 PM
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are you referring to the red handle valve that is on the 3/4 line leading to the expansion tank?
 
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Old 10-04-11, 07:52 PM
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I believe he is... reason we don't like to see anything but ball valve is so that air can float right through. Don't want anything to impede the air from going up that pipe and back into the tank. That looks kinda like a GATE valve to me though, what I can see of it anyway... and that's better than a regular old STOP valve. Problem with those is that they don't really always shut off tight when you need it to. And sometimes they don't open again!
 
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