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I'm back with my non opening Zone Valves

ebrady07 Member Posts: 10

Hi everyone I'm back. So here are a couple of updated pictures of my setup. I identified the power line to the zone valves with the green tape on the left side. Then the blue tape line goes directly to the Aquastat and those are attached to the two end switch screws. Still no luck in getting them to turn on automatically though. I checked the TR line of each zone with the multimeter and each is getting power. I have also noticed that the pump that pushes the water up to the baseboards never turns off. The second picture is of the aquastat and the relay. The relay has gone bad before and the aquastat is original (1987). Not sure if either of these things could be why the zone valves are not turning on though. Any advice? Thanks for all your help!


  • mattmia2
    mattmia2 Member Posts: 9,838
    edited December 2022
    Where does the thermostat cable to the control on the left go, the one without the blue tape? Connecting those wires is what turns on the circulator and fires the boiler.

    What model is the aquastat on the right, is it close on rise or open on rise?
    EBEBRATT-Ed Member Posts: 15,737
    edited December 2022
    possible you have too many valves on 1 transformer. Most allow 3 valve per transformer.

    Also @mattmia2 question about the aquastat is important I would assume that is a low limit to shut the pumps down if the boiler water temps drop. Do you get domestic hot water off the boiler? If so that aqustat would break on a drop in water temp to shut down the pumps and would be set at 120-130.

    It's set at 200 I don't see that being a high limit wired like that. Find the cover for that aquastat that will tell you if it is wired for a high or low limit depending on the wiring terminals connected and the model of the aquastat
  • hot_rod
    hot_rod Member Posts: 22,342
    Are the zone valves actually going to open position when you turn up the thermostat? Take the cover off and notice a brass gear inside. It needs to move over and “rub” the micro switch open. Also the flat lever should be loose, floppy when the valve is powered open.

    If the valves are not powering open completely, no need to troubleshoot the end switch, do a step by step troubleshoot. That valve needs to power fully open to make the end switch. Moving the lever manually will not make the switch.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • 109A_5
    109A_5 Member Posts: 1,388
    Hello @ebrady07,
    I would wire it like this. The left hand Aquastat is for the operational control. The right hand Aquastat is a safety limit switch and is normally closed unless the boiler water go over 200° F. Once it is wired correctly you may be back to the original problem.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Zman
    Zman Member Posts: 7,588
    Do you have an electrical meter and some know-how?
    You could clean up that mess and fix your circ relay issue with one of these https://www.supplyhouse.com/Taco-ZVC405-4-5-Zone-Valve-Control-Module-with-Priority
    You would then know at a glance whether the t-stats are calling and if the end switches are closing
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein