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  1. #11
    Join Date
    Feb 2013
    Posts
    7

    Default Re: Thumping in the Radiators

    Thanks for all the support here because there's some confusion on my part.

    I have a forced hot water system; not steam, as I previously noted. The system that controls the heat is in the basement and I have radiators on the first, second, and third floors of the home. The radiators on the first two floors work fine. There are three rads on the third floor - one is hot to the touch, one is warm, and the third is cold. When I try to bleed the rads on the third floor, sometimes water and air come out, sometimes just air, sometimes nothing happens.

    As far as I can tell we don't have hard water and I haven't heard any other noises coming from any other place other than the radiators. I say, as far as I can tell because we've only lived here for a little over a year so I don't have much experience (hence the confusion before) with the system.
    Last edited by arevely; 02-12-2013 at 10:26 AM.

  2. #12
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,168

    Default Re: Thumping in the Radiators

    Quote Originally Posted by JLMCDANIEL View Post
    I have never heard of a hot water single pipe system.

    Jack
    This post has me confused. But that doesn't take much lately.

    John

  3. #13
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,555

    Default Re: Thumping in the Radiators

    Quote Originally Posted by johnjh2o View Post
    This post has me confused. But that doesn't take much lately.

    John

    John in an earlier post the OP said he only had a single pipe going to the radiators.

    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  4. #14
    Join Date
    Feb 2010
    Location
    South*East
    Posts
    1,168

    Default Re: Thumping in the Radiators

    Quote Originally Posted by JLMCDANIEL View Post
    John in an earlier post the OP said he only had a single pipe going to the radiators.

    Jack
    I saw that Jack, that's were the confusion comes in. One pipe can only be a steam system. Then the next thing we get is the gauge is reading 12 psi. That doesn't happen with one pipe steam.

    John

  5. #15
    Join Date
    Feb 2013
    Posts
    7

    Default Re: Thumping in the Radiators

    I'm, again, sorry for the confusion. When asked if we had a single pipe or double one, I was looking in the wrong place. In any case, I now have the correct information: we have a double pipe, hot water system.

  6. #16
    Join Date
    Jul 2009
    Posts
    137

    Default Re: Thumping in the Radiators

    arevely,

    You need just a LITTLE HIGHER pressure on the "altitude" or "water pressure" gauge at the boiler for the water in the system to reach the height of the 3rd floor rads---generally, the 12 psi water pressure you have on the system now is lifting the water in the heating pipes/rads to under 30 feet---this is high enough to allow heat for the 1st & 2nd floor rads, but is not high enough to reach the 3rd floor rads---as a result, you have mostly AIR in the 3rd floor rads, which is why you get nothing when you bleed them, and also why the system pump (when it comes on) mixes the air with the water & you get a thumping noise---so our task is to: 1) make sure the water supply valve that allows fresh water into the boiler system automatically is OPEN; sometimes the previous homeowner improperly closes this valve & the system can't re-supply boiler water automatically; the water supply valve looks like a regular faucet (see taco site diagram below--they label it "cold water supply") that connects the house water supply to the boiler water supply; the house water supply is generally at 50-70 psi; the BOILER & the rest of the heating system is kept at between 12psi & 16 psi as a safety measure & to minimize leaks; task 2): raise the system pressure to 16 psi, and task 3): bleed all the air out of the 3rd floor rads so we get a quiet system.

    As the moderator noted in a previous post, there is a water inlet (pressure reducing) valve on a pipe next the the boiler that has to be opened when the system is relatively cold to allow a little fresh water into the boiler until the needle on the altitude gauge dial reads approx 16 psi---this should allow the 3rd floor rads to completely fill with water, except for a small pocket of air, which you can then remove by opening the 3rd floor rad bleed valves.

    Click onto the images below to see what the water inlet (pressure reducing) valve near the boiler looks like; the taco site below shows a "dual control", coupled with a "pressure relief valve" mounted on the boiler---this may be how it looks on YOUR system, instead of a single, stand-alone valve--also note, the taco site also has instructions on how to INCREASE THE PRESSURE of the boiler water slightly by 1) loosening the locking nut on the little vertical screw on the valve; 2) turn the adjusting screw with a screwdriver CLOCKWISE a few turns & note the boiler pressure gauge needle reading, until it goes up to 16 psi; then lock the vertical screw by tightening the locking nut.



    http://www.grainger.com/Grainger/BEL...ng-Valve-6LFA3
    http://managemylife.com/mmh/question...cing-valve-set
    http://www.taco-hvac.com/uploads/Fil...20(102-006.pdf
    http://orders.sidharvey.com/IMAGES/c...d/20104-16.pdf
    Last edited by Pelton; 02-12-2013 at 08:56 PM.

  7. #17
    Join Date
    Feb 2013
    Posts
    7

    Default Re: Thumping in the Radiators

    Man, this is great stuff. I will try this and let you know what happens. This makes perfect sense, and I think will eliminate the problem. Thanks so much to all of you for your help and sorry for the confusion!

  8. #18
    Join Date
    Feb 2013
    Posts
    7

    Default Re: Thumping in the Radiators

    Okay, here's the deal: after trying the things suggested, I discovered that water wasn't getting to the third floor radiators. I called in an HVAC technician who's here now. He drained my expansion tank, is putting in some new pipes (the pipe that is used to fill the system is old and corroded), and installing a new pressure relief valve. Hopefully the bill won't be too painful, but at least, I'll have heat to the third floor and no more thumping!

    Again, thanks to all of you who contributed ideas. I know where to go with any other house related problems in the future.

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