Cold water locked in one zone

Discussion in 'Boiler Forum' started by j31415, Dec 4, 2009.

  1. j31415

    j31415 New Member

    Dec 4, 2009
    There are 4 zones in the house and the 4 returning pipes connect to one circulator. One zone (ground floor) doesn't seem to be working in the sense that the pipe is cold between 10 inches into the supply pipe of that zone and all the way past the zone valve to where the returning pipe of that zone converges with other returning pipes.

    As a temporary solution, (when I feel cold) I would just shut off the returning valves of all 3 other zones, shut off the valve upstream of the circulator, and bleed the system to get the water pushed through. Hot water would run for 30min to few hours, then the flow would stop again.

    Is it a air lock problem or the pressure is not right? Any other permanent fixes? Thanks guys!

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    It's likely that you have an air leak and that zone is blocked by air. The boiler water pressure, especially on the first floor when the upper ones are working, probably isn't an issue. The pressure is more to keep the water from boiling, but it does help keep air from infiltrating. Normally its somewhere 12-16# or so.

    If your expansion tank is nearly shot or its precharge pressure is not right, in between cycles when things cool off, any potential air leak could be sucking in air. these may not leak water, since when hotter, things expand. Look at all of the joints for evidence of (minor) water leaks. If you find any, they'll suck air when things cool.

    You may also need to service or replace any air extraction device you may have on your piping. Normally, air migrates to the top floor, or high point in the system, but could stop at the first floor depending on how it is plumbed.

    If the system is leaking water, and the system has an autofill valve, the new water will have some air disolved in it. You need to find the leaks, as this constant source of air and oxygen can promote corrosion in the system.
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  4. j31415

    j31415 New Member

    Dec 4, 2009
    Jim - thank you so much for the reply. So two of the drain valves are leaking water and one of the zone valve has calcium deposits around it. Could air get in from there? Also is there any special tricks to find leaks or do I just have to feel the line all the way through? Lastly any thoughts on spirovents? I'm thinking about putting them in the system. Thanks! -James
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