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Bleeding air every day?

Kevin Doll
Kevin Doll Member Posts: 10
Hello - We purchased our 1930's 3,900 sq foot house last fall. I have a Weil McClain CGM-8 Series 6 that appears to have been installed in the early 80's. I have 8 rad's on the first floor, 2 are capped, but the remaining 6 work fine. At some point, the 8 rads on the second floor were removed and a coil was installed in the attic in an air handler. Down stairs I can set and sweat. My service man installed a new air vent (I think he called it a Hoffman?) on the coil as it was leaking. Hot water never would get up to the coil last fall. This seems to have helped but not fully. There is a main air bleeder that drops down from the attic in one of the bedroom closets. We ran the pressure up to 20 lbs and bled it for awhile, which seemed to help get the hot water to the coil. We dropped it back down to 12 lbs. I still don't seem to get decent heat out of the coil. I have bled this main bleeder every day for about 4 weeks. Air hisses out for about 20 seconds, and then nothing, no air, no water, nothing. I can't think that I have to bleed it every day? Why am I not getting to water yet? My assumption is that when they capped all of the rad's on the second floor - that I just have a big spiderweb of pipes with air in them. Any way to get all of this out? I wish that the upstairs rads were still there - but nothing I can really do about that now, so I need to get this figured out as we are coming into the second winter in the house. I appreciate any and all help. Thanks. (Note - in reading the other posts - I know that I have not given you enough info yet - ask me for what you need to help and I will try to get it for you. I am new to this style of heating but have been learned quite a bit from this and other sites.) thanks

Comments

  • John Ruhnke1
    John Ruhnke1 Member Posts: 154
    Air problems

    > Hello - We purchased our 1930's 3,900 sq foot

    > house last fall. I have a Weil McClain CGM-8

    > Series 6 that appears to have been installed in

    > the early 80's. I have 8 rad's on the first

    > floor, 2 are capped, but the remaining 6 work

    > fine. At some point, the 8 rads on the second

    > floor were removed and a coil was installed in

    > the attic in an air handler. Down stairs I can

    > set and sweat. My service man installed a new

    > air vent (I think he called it a Hoffman?) on the

    > coil as it was leaking. Hot water never would

    > get up to the coil last fall. This seems to have

    > helped but not fully. There is a main air

    > bleeder that drops down from the attic in one of

    > the bedroom closets. We ran the pressure up to

    > 20 lbs and bled it for awhile, which seemed to

    > help get the hot water to the coil. We dropped

    > it back down to 12 lbs. I still don't seem to

    > get decent heat out of the coil. I have bled

    > this main bleeder every day for about 4 weeks.

    > Air hisses out for about 20 seconds, and then

    > nothing, no air, no water, nothing. I can't

    > think that I have to bleed it every day? Why am

    > I not getting to water yet? My assumption is

    > that when they capped all of the rad's on the

    > second floor - that I just have a big spiderweb

    > of pipes with air in them. Any way to get all of

    > this out? I wish that the upstairs rads were

    > still there - but nothing I can really do about

    > that now, so I need to get this figured out as we

    > are coming into the second winter in the house.

    > I appreciate any and all help. Thanks. (Note -

    > in reading the other posts - I know that I have

    > not given you enough info yet - ask me for what

    > you need to help and I will try to get it for

    > you. I am new to this style of heating but have

    > been learned quite a bit from this and other

    > sites.) thanks





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  • joe_14
    joe_14 Member Posts: 138
    purge

    how many feet from the boiler to the coil is the air handler. you may need to run the pressure higher at the boiler to get the water up to the coil. for every 1lb of pressure on the boiler you lift water 28 inches. you my need to run the pressure around 18lbs. purge the complete zone from the purge station on the return piping at the boiler. keeping the boiler pressure at about 25lbs while purging. when done purging adjust pressure back to 18lbs. you should also increase air pressure in the expandsion tank to match system fill pressure this will allow proper expansion on the system. also you may need anti-freeze in the system to protect the coil from freezing. its located in the attic?

    hope this helps joeg.
  • John Ruhnke1
    John Ruhnke1 Member Posts: 154
    Air problems

    Kevin,

    Your problem is that you most likely don't have enough pressure to go to the second floor. You need to have 1 pound of water for every two feet of height. With the boiler in the baeement and the air handler in the attic, the air handler must be about 26 feet higher then the pressure guage at the boiler. The pressure at the air handler will always be 13 pounds less then the pressure at the boiler. Now when you drop the boiler pressure down to 12 psi in the basement, the air handler coil has a negative pressure of 1. Now when your attic air vent is opened air gets sucked in instead of being pushed out. Thus the air vent adds air to the system insead of removing it. Raise the pressure to 20psi at the boiler so that the attic is under 7 psi of pressure and your air problems will be greatly improved. The 13 psi difference is just a rough guess on my part so add about 7 psi to cover yourself. The boiler pressure always fluctuates with temperature differences. The fluctuation can be bigger or smaller depending on the boiler piping and the size of the expansion tank. When the boiler is at its heighest pressure make sure the pressure isn't above 25psi. At 30psi the basement will flood because the relief valve will pop. If your boiler can't maintain a minimum of 20psi with a maximum of 25psi then you may need to repipe things. I would call the original installer of the coil because that is his responsibility. He changed things in your system and should have changed things at the boiler to accomendate the higher elevations. If he did'nt then the job was not done right. Call him back and ask him to fix his mistakes. The boiler room changes should have been incuded in his estimate.

    JR

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  • Dale
    Dale Member Posts: 1,317
    pumping away

    I agree with the other posts about what static fill pressure you need, you can also fill till water comes out the highest point, there should be a vent there, and then add 4 pounds. I would also make sure the boiler pumps away in that the pump is on the supply, and you may need to add a small pump, in a primary secondary sort of way to the beginning of the hydro air zone. I would do that last.
  • Kevin Doll
    Kevin Doll Member Posts: 10


    Joe / John / Dale
    1. I don't have a basement - but you were very close, I measured from the boiler to the air handler in the attic and it is about 22'.

    2. The serviceman showed me how to add water to the system using the fast fill, so I can take it up to 18 lbs. Does the system need to be running for awile? We have had a couple of mild days and I assume the water tempature will affect the pressure.

    3. I don't see anything on the expansion tank on pressure. It is a No. 30 Thrush, and all it has is a valve and a nozzle for a hose fitting. Do I need some type of gauge to screw on?

    4. The serviceman said that I was lucky that the coil hasn't frozen already, I assume that the antifreeze that you are talking about is not normal car antifreeze, and I assume that this is a job for a professional?

    5. The pump appears to be on the return side, as it is right before the boiler. I don't see anywhere to purge air from here. The only thing that I see is a 1/4 turn valve with a short 2" pipe coming straight down from the pump before the turn into the boiler. I assumed if I opened this I would get a ton of water coming out. The serviceman did mention adding an additional small pump in the attic just before the coil, but he said this would be messy as they just sweated the pipe to the coil, there is a valve on teh supply side, but not on the return. From what I have read on the site, and from what you mentioned, do I need to go ahead and have my pump moved to after the boiler on the supply side? Is this a major expense? I doesn't seem like moving it 12"'s would make that big of a change but I see everyone talking about it.
    thanks and looking forward to more advice.
  • David Sutton_3
    David Sutton_3 Member Posts: 160
    pumping away will help

    by moving the circ to the surply side and pump away the boiler becomes the low presure point and the system will be the high side , this will aid in driving the air into suspention and bring it back to the boiler were it can be released. i would get someone in there who understands this and have them do it for you, you will continue to have this problem if you dont take care of this. and i would have no-burst added to the system to prevent frezzing good luck..David
  • Big Ed
    Big Ed Member Posts: 1,117
    Web Of Piping

    I see a problem with the second floor .All that unused and capped piping is going to hold a lot of air . This supply with work like a second expantion tank location . Which makes the system sloppy and I'am sure is the source of your air lock problem.

    Solutions , Yes pumping away is a great way to g and will remove the unwanted air. In the mean time could you add a float bleeder up on top of the coil.For added protection from ceiling damage,attach a piece of tubing to the vent and lead it to the outside , drain or ventpipe. Try to bleed the air from the unused piping or better yet disconnect from the system..




    FYI.... Another problem I pick up on .You mentioned that you sweat down stairs ?I assume that you have large cast iron radiators ? A coil runs on 180-200 degrees while a ci rad runs 0n 100-160 degrees .If the temp of the boiler is set for the coil you will sweat in the ci radiator area. You need a system bypass for the radiator loop..
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