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Thread: Air in the system - heating system, please help

  1. #1
    DIY Junior Member barryr22's Avatar
    Join Date
    Jan 2011

    Default Air in the system - heating system, please help

    I am new to this forum, and hope I posted my question in the right place.
    Thanks in advance for any help.
    My son had recently moved to a “new” house.
    The house is located in Long Island, NY.
    The house was built in 1960, and has the original heating system.
    The system is a hot water baseboard.
    The boiler is an oil boiler, Sunray IV, made by National-US Radiator Corporation, which is no longer in business, nor can I find any information on this boiler.
    The house heats up in few minutes, no problems here.
    The problem is that there is air in the system, and it is noisy.
    When we bleed the air, the system is quite for a short while, but after a week or two, the noise comes back.
    I did some research and came across some air eliminators, such as the Spirovent Air Eliminator, which I consider to install.
    I checked for any water leaks, and couldn't find any.
    In addition, the system does not have an expansion tank, but rather, it has a water tank which hangs from the ceiling.
    The other day I called up tech support at Amtrol, to get some advise on an expansion tank, and I was told that most likely the tank is full with water, and I should drain some of the water out of the tank.
    The size of the tank is about 23 Gallons, and he recommended draining 1/2 of it.
    Once we did so, the noise became worse than ever before.
    I am planning to call him back.
    Does any one here, may have any suggestion as to how can I deal with the air in the system.
    Should I eliminate the water tank and replace it with an expansion tank?
    Also, is there a way, if so needed, to add/refill the tank with water?
    Any help is greatly appreciated.

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    The tank is there to provide room for the varying volume of water, based on it heating and cooling. That type of tank needs some air in it to enable that expansion and contraction, but, it also gets some disolved in the water, that can then come out in the high points. My personal opinion is that a bladder tank is better...no air in contact with the water. An air scoop like the SPirovent should help. When circulators get older, they can inject air when their seals get worn and when things cool off, you can suck air into seals that might not leak water. If you change the tank and add a good air eliminator, it should help. Depending on the design, it can be hard to get all of the air out of a system.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    In the Trades Tom Sawyer's Avatar
    Join Date
    Nov 2010


    Systems been there a longtime without issues so adding things may stop the noise but not the cause. The expansion tanks should be totally drained, not 1/2 way. The water feed valve should be set at 12 to 18 lbs. If you are getting air in the system its either one of two things. either there is a leak somewhere or, the high limit is set too high or is defective and the boiler temperature is going to the point where it makes some steam when it runs.

  4. #4
    Network Engineer rmelo99's Avatar
    Join Date
    Jul 2006


    It sounds like you know what you are talking about when you mention it has air, but you didn't specify the type of sound or how you know it's air. The reason I bring it up is that some people have sounds (banging) and immeditatley think air. There are other things that can cause sounds. Like zone valves slamming shut and creating a bang.

    Just throwing that out there. Most of the time air is the problem with HW heating systems, but not always. The other posts have valid points to look into also.

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