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Beelding baseboards

Gerry May
Gerry May Member Posts: 22
An old 2 story office / residential with cast iron baseboard radiation. Went on no heat call. Boiler's working, has a pump on return, Extrol hooked up to supply from boiler. Sounded gurlging in the boiler room. So I shut off the pump, bled radiators. Got heat. 3rd day, same thing. CHecked for pressure in Diaphram Tank, spit out water. Replaced expansion tank and set to static fill pressure of 18PSI then started bleeding. Here's the problem: turned the bleed valve open...air came out. Removed another pint of water, water stopped trickling out of the bleed valve. Left valve full opened and absolutely nothing came out...no air no water. Ran the pump, shut it off. Bled again, same result. Double checked pressure..18 PSI. Should be good for 2 story building.. Less than 20 feet between the bottom of the boiler and highest radiator. This happens to only one baseboard radiator. All others are okay. All ceilings and walls are covered...don't know if it's Monoflo system or not.

Any suggestions?


  • Brad White
    Brad White Member Posts: 2,398
    There you have it as an initial cause

    "Boiler's working, has a pump on return, Extrol hooked up to supply from boiler."

    You have to "pump away" from the expansion tank.

    This is how air gets drawn into water. All of the circulator energy is going to produce a sub-atmospheric pressure on the suction side which will draw in air. (The point where your expansion tank is connected is a point at which the pressure will not change, therefore that pump energy has to show up somewhere...)

    Until you move the expansion tank connection to the suction side of the circulator, you will have a bountiful repeat business call schedule for which you may not be paid.

    EDIT- I like Weezbo's more targeted response, no question...
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"

    -Ernie White, my Dad
  • Weezbo
    Weezbo Member Posts: 6,232
    if the system once had zone valves...

    i would hazard a guess that one of the rubber balls is floating around in the system or if it is fed by copper...that one of the heat expand leak stoppers did not behave as advertised.

    Here is another reason that you might not get any water out of a radiator or baseboard,...it was never connected.

    if you pull a vacuum every time it rolls then you might see some other problems surface like water all over the ground from the system purging out of the relief valve...
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