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  1. #1
    Join Date
    Jan 2009
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    Default bleeding a radiator (gas boiler heater)

    Hi All.

    I hope this is the right forum to post to... if it isn't please let me know which it is, and I will repost there.

    I have a room in the upstairs of my house that is cold. I have gas boiler heat, and all of the other rads generate good heat. I have verified that the valves are on, and when I open the bleeder valve there is a strong 'hissing' sound... but no water comes out.

    I have turned up the heat to 25C, and I feel heat which seems to be migrating across the rad, but it is taking a long time.

    Am I doing everything correctly, or is there something else I have to do? (i.e. wait longer, leave the valve open while the heat is at the higher level, etc).

    Regards

  2. #2
    Join Date
    Jul 2009
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    137

    Default Re: bleeding a radiator (gas boiler heater)

    azrael2000:

    Are you in Canada?? It sounds like there is not enough water in the problem rad, for whatever reason; this time of year those of us with hot water heating systems have to go around especially to the 2nd floor rads for the annual ritual of bleeding the air out---they have been sitting idle all summer & air tends to accumulate in the upper floor rads & in October when the heat comes on the air has to be removed using the rad bleed valves; use an empty plastic margarine container, or plastic cup, hold it under the bleed valve & open it with a screwdriver or coin, leave the valve open until water comes out; if ordinary bleeding doesn't do the trick, read on to answer the following questions.

    I think 25 degrees Centigrade equates to approx 77 degrees F? for us Yanks south of the border. Yes?

    Is the non-heating rad on the 2nd floor the only rad on the 2nd floor, or are there others up there that are heating OK??

    Have you allowed the bleed valve key to remain open long enough while you hear hissing to see if water comes out?

    Has this rad recently caused this trouble, or has it been causing this problem for some time?

    How many feet (meters/metres) approx would you say the 2nd floor rad is in height above the boiler?

    What is the water pressure (altitude) meter needle on the front of the boiler pointing to when the boiler is cold-----in the U.S. this is usually 12 to 15 psi (approx 77 square cm)---if the reading is lower than this you need more water in the pipes---there is an on/off valve near the boiler coming from the house water supply----if the dial reading is low, open the valve (if you can find it) to let more water into the system---there is a pressure reducing valve near the boiler that will allow only 12-15 psi (77 sq cm) water pressure into the boiler, so don't worry about adding too much water.

    You may have different boiler dial readings (sq.cm) based on the metric system that differ from the ones used in the States, so copy down what it says on YOUR boiler.

    Please post back.
    Last edited by Pelton; 10-10-2012 at 04:32 PM.

  3. #3
    Join Date
    Jan 2009
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    8

    Default Re: bleeding a radiator (gas boiler heater)

    Hi there.

    Sorry for the delay in my response.

    In answer to your questions, and in no specific order, yes I am in Canada <smile>

    I have a Weil-Mclain Series 11 gas boiler. When I look at the unit, I don't see any filling valves, but they could be someplace under the front cover, which I didn't check (My understanding is taking off the cover kills the boiler, and didn't want to risk it).

    On the gauge on the side, I have a PSI of around 10 - 10.5. The temperature in Farenheit is 110.

    When I open the bleeder valve on the top of the radiator in question, which is on the top floor of the house, I hear air come out, but don't feel any water. When I touch the pipes leading to the unit, and the furnace is running, they are warm / hot. Touching the unit, the warmth seems to go around 1/2 way up.

    There is another radiator on this floor, and it seems to be putting out heat no problem.

    All of the other radiators in the house are hot when you turn the heat up.

    Regards

  4. #4
    Join Date
    Jul 2009
    Posts
    137

    Default Re: bleeding a radiator (gas boiler heater)

    azrael2000:

    Ok, 10 psi on the boiler gauge is a little low----especially if you want to get the water all the way up to the 2nd floor; there is usually a horizontal copper pipe right next to & slightly above the boiler about 2 metres from the floor with a regular on/off faucet valve (much like the outside faucet on the garden faucet).

    You should be able to trace this 1/2 copper tube as it goes thru a pressure reducing valve & then enters the boiler somewhere near the front top; turn the handle on the faucet-type valve counter clockwise to let additional water into the boiler/piping system, which will raise the height (altitude) of the water in the system, so that it fills the non-heating rad on the 2nd floor.

    The site below has a diagram of the "cold water supply" handle going into the boiler.

    Post back if you don't hear any water entering the boiler, or the needle on the gauge doesn't go to at least 12 psi.



    http://www.taco-hvac.com/uploads/Fil...20(102-006.pdf
    Last edited by Pelton; 10-11-2012 at 09:08 PM.

  5. #5
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    975

    Default Re: bleeding a radiator (gas boiler heater)

    I always bleed my hydronic rads until water comes out is a steady stream (it will spit air and water for a while). You want all the air to be replaced with water, or you're airlocked with no water flowing through the rads.
    Start with the highest bleed valve in the house and work down to the lowest.
    If the system has been drained down or any reason, the bleeding will have to be repeated a few times to ban all the air.
    Casey
    Remove not the ancient landmark, which your fathers have set.

  6. #6
    Join Date
    Jan 2009
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    8

    Default Re: bleeding a radiator (gas boiler heater)

    Thanks for all of the replies everyone.

    I have been doing bleeding of the units, slowly... but surely.

    Some of the radiators had hair in them; and as you suggested I let them run until not only air stopped coming out, but the water ran clean. (there was some black particulate coming out of some.)

    There are two radiators upstairs, and one now is supplying good heat. the other one, as I stated earlier, seems only to heat about half way up and about 70% across.

    I am going to turn the bleed valve open, then run the bleeds in the other units; hopefully that will help. I will keep you advised. I will also see about bringing the water pressure up to the 12 psi suggested. (I know I said it was at 10, but my eyes aren't good, and it was dark down in the basement, so I will also double check to ensure it isn't higher than first stated . I'm old... <grin>

    Regards

  7. #7
    Join Date
    Jan 2009
    Posts
    8

    Default Re: bleeding a radiator (gas boiler heater)

    Hi All.

    Well, taking the advise I have found here, there have been a few small changes.

    After cranking up the heat to 24C, I opened the valve on the failing radiator, and listened. I heard a gurgling sound, kind of like what you hear when something is filling up. I have left the air valve open and put a container underneath it to see if time will help.

    As to the pressure issue, I have checked for the water fill as was suggested earlier. The only tap that I can find connects to a :fill trol" container and goes into the furnace. The valve feels like it is opened all the way.

    Any other ideas / suggestions?

    Regards

  8. #8
    Join Date
    Jul 2009
    Posts
    137

    Default Re: bleeding a radiator (gas boiler heater)

    azrael2000:

    At this point, I think it would be best if you called in a service person to take a look at your system; the fact that the other 2nd floor rad is full & working, & the fact that there is little or no water in the rad you're working on, and the "hair & dirt" you're getting out of the bleed valve could indicate that the piping system is blocked with dirt, or worse, there's a leak somewhere in the piping.

    The entire piping may have to be pressure purged with clean water to get the dirt & other debris out before you can have your heat back in this rad.

    In the meantime, I would not leave the bleed valve open---water could appear unexpectedly & cause a lot of water damage to your home.

  9. #9
    Join Date
    Jan 2009
    Posts
    8

    Default Re: bleeding a radiator (gas boiler heater)

    Update: Well, taking all the advice here, since nothing changed, I called in a tech. (I didn't realize it until speaking with a co-worker here, furnace service was something I paid for monthly! Didn't cost me anything).

    Anyway, I had a unit (Fill-trol) that was used to increase the water pressure. It had died, so the only thing that was getting water to the upper floors was water pressure! Might also explain why my water pressure to bathtub, etc was low when running 2 things. Going to have to check that.

    After the replacement, the tech and I went upstairs and bled the upper unit(s). Now I have heat.

    Thanks to all.

    Regards

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