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Relay Activates pump for unknown reason?

pm1176 Member Posts: 1
edited August 2016 in Thermostats and Controls
Radiant floor heat. Wirsbo two-wire Thermostat. Four Wire valve bodies. Taco SR504 switch relay.

For some reason..about a week ago, one zone decides that the circulation pump needs to turn on and run but the valve remains closed. I can open the valve both manually and by the T stat and the audible click lights up the orange lights on the Uponor Zone Control module. The red light "D3" remains lit no matter what...at all times. Any leads on how to stop this issue or what is causing this? Faulty valve? This is on an oil fired boiler unit and prior to a week ago, the system would only fire off for domestic hot water use- no need for floor heat during this time of year. Thank you all.

***red light can be seen in one photo without flash****

Are thermal valves better than motorized valves or is there a better one out there?


  • Jamie Hall
    Jamie Hall Member Posts: 23,655
    The end switch on the valve is controlling the circulator? That's common enough. If so, that end switch isn't opening.

    In general: figure out what switch or relay is actually controlling the ckculator (this may take some research and wire tracing) and the odds are good that that contact isn't opening properly.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Paul48
    Paul48 Member Posts: 4,469
    Why do you have a switching relay, and a zone control, and how did you marry the two?
    JUGHNE Member Posts: 11,109
    Stuck switch.......as long as the homeowner is not watching. o:) ....a good "thump" with the rubber handle of a screwdriver might open that switch. This is high tech....knowing where to apply the "thump".
    So carefully whack each valve and wait for the pump to stop. Might work.....just don't dent anything.

    For this technique I support one side of the suspect with one hand and apply the persuader with the other hand......it has worked for a lot of stuck items.
  • BobC
    BobC Member Posts: 5,481
    Rubber handled screw drivers were one of my favorite technician aids when repairing the mail sorting machines at the post office.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Paul48
    Paul48 Member Posts: 4,469
    It was a heck of a lot faster than checking voltage at a couple hundred contact blocks. I worked on printing presses that had the old relay-logic controls.

    Back in the late nineties, I had a new car that kept shutting off, while driving. I took it back to the dealer, and he gave me a loaner. At the end of five days, he told me I needed to take it to a dealer in another town. He said they have better equipment. So, I took it to that dealer, and told him what the other one had said. He laughed, and said,"they have the same equipment I have". Anyway, I left it and he called 2 hours later and said it was all set. When I picked it up, he said it was the computer ($100 back then). I asked him how they found the problem. He said, " we take the computer out of the back of the glove compartment, and put it on the floor of the car. Then we send 2 guys out in the car, and one taps on the side of the computer. When he did that, it died".
    So........It's not mutually exclusive of any one trade.
  • Shomeowner
    Shomeowner Member Posts: 1
    Pm1176 - did you figure out your problem? We have the exact same issue and could use your help!
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 8,167
    The last time anyone heard from @pm1176 was nearly 6 years ago. And all they did was ask the question. @pm1176 has not graced us with any feedback in all that time. So, I guess they either still have the problem and are living with it, OR, a professional found the problem and we will never know about it .

    I would suggest to @Shomeowner to start a new discussion and allow us to help you. Please offer up some pictures of the relay in question, and all the other components you have, including zone valves, circulator(s), thermostats, and perhaps a picture from far enough away so we can see how all the components are connected.

    Covers off of the controls so we can see the wires and what terminals they are attached to.

    Edward Young Retired

    After you make that expensive repair and you still have the same problem, What will you check next?

  • Dave Carpentier
    Dave Carpentier Member Posts: 604
    FWIW - If it was bad MVA switches... When my MVAs had end switch issues, I was changing the switches inside ($0.25 repair). But that was back when MVAs were $125 each. At some point, I got tired of doing that and just started swapping them out with thermal ones. The OP had a mix of MVA and thermals, so his were probably started to fail out. I bet an hvac guy (or gal !) swapped it out to thermal and all was fixed.
    Its too bad more people dont come back with results.
    30+ yrs in telecom outside plant.
    Currently in building maintenance.