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Gurgling upon startup

vfrjim Member Posts: 4
I recently upgraded my 2 zone hot water system to a 4 zone system and have had a problem. When it calls for heat in 3 of my 4 zones (upstair zones only, the basement zone does not do this), a rush of air goes through my baseboards till it gets back to my circulator and hits my SpiroVent Jr and vents out the air and all goes quiet since it removes the air very efficiently. All zones have an Auto vent on the first elbow as the water leaves the boiler.

One thing that I did notice is that when I remove the individual vents is that all 3 zones that have the problem is that when the system is not running that there is no pressure at the vents and that I can remove the vents with very little water coming out but on the 4th zone (the one that works without air problems), it is under full pressure and leaks immediately upon removal.

The boiler is set to 12 - 15psi, the taco 007 circulator is on the return, the amtrol expansion tank is also connected at the return with the Spiro Vent Jr is located just before the Taco Zone valves.



  • icesailor
    icesailor Member Posts: 7,265
    Gurgling Jug:

    It is hard for me to visualize your piping but I have encountered something similar. And it could happen because you added to something that was already there. Was the cellar zone a origonal zone?

    IMO, the circulator on the return is a red herring and is in no way the cause. But what can be a cause is that if the zone valves are Taco 57* types, they are positive shut-off valves. If you have a flow check, AKA a flow control valve, and it is closed, and the extrol tank is between the zone valves and the flow checks, it can cause a no pressure situation in the loops while thermal contraction causes the water in the loop to contract. When doing this, it will draw air into the loops.

    This is not easy to explain and if you are not a heating professional and do not understand the complicated rules of physics, it will be difficult to see if this is the problem.

    But some combonation of this is your cause. No other way can you get so much air into the system unless there is something very obvious that you haven't mentioned. If you don't have any automatic air vents in the system, the system would pull a vacuum and that would be that. With the auto vents, they will suck in air every time the system goes negative.

    If you have  a flow check or more than one of them, try opening the valves and see if the problem stops.

    Years ago, we always used flow checks as a 90' ell coming off a boiler and put a plug in the end. Then a air scoop with the extrol hanging out the bottom. Then, the zone valves. I always left the flo check closed. I read somewhere about boilers overfilling because when the flow check and zone valves were closed, I had effectively isolated the extrol from the system. Only when the zone valve opened would the extrol be introduced back into the system.

    Now, I make the turn with a 90' ell, air scoop device, then the flow check, then the zone valves. That way, the extrol won't become isolated.

    Some may question the placement of a flow check at all. Because I use tankless and water storage tanks, I don't want gravity flow when the circulator is off when the return water is cold, and if a head goes bad, I can remove the #3 wire, open the valve manually and let another zone until I can get to fix the problem.  
  • vfrjim
    vfrjim Member Posts: 4
    edited November 2010
    I think your right

    I think you hit the nail on the head, I have flow control valves (check valves) on the 3 zones that are causing the problem because when I designed the system (I am a layman only) and I share one return pipe back to the boiler to all three zones (the original zone in the basement has it's own return line and no check valve)

    So, should I remove the check valves? Was it improper to have them so it would force the water to return to the boiler and not go into another zone??

    I do appreciate the help.

  • vfrjim
    vfrjim Member Posts: 4

    I have tested with the zone valves manually opened and do not have the problem at all but if I leave these open, I in effect lose my zoning of the 3 zones to be 1 zone since they will always run together.
  • icesailor
    icesailor Member Posts: 7,265

    No, just scew the wheel on the top of the flow checks "up" so the disk is off the seat. It is to stop the flow by gravity but a zone valve is just a motorized flow check.

    You should not need to remove the flow checks.

    The only reason you need them is because of an obscure reason and I explained that.
  • vfrjim
    vfrjim Member Posts: 4
    Thanks for the help

    I actually had to remove the check valves since they were not adjustable types and all is quiet now. Live and learn.

    Thanks for the help!
  • icesailor
    icesailor Member Posts: 7,265

    De Nada.
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