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Circulation pump running constantly

Beakster
Beakster Member Posts: 7
in Radiant Heating
Hi,

Notice today that my house was too warm and yet I could hear the heating running.

It's multizone hydronic flooring heated by an electric boiler.

I looked at my zone valves and they were all closed, as they should have been.  But I could feel and heat the pump running and it was very hot in the heating cupboard.

I checked the voltage to the pump and it was on, so i disconnected the neutral wire.  

What could cause this? I am guessing a stuck relay in the control module?  Is this likely to be repairable?

When the boiler has circulation does that mean it constantly heats? Is it safe to just disconnect the circulation pump power?



Thanks




Comments

  • hot_rod
    hot_rod Member Posts: 23,142
    Either a zone valve end switch is stuck closed or the circ relay. Disconnect the end switch leads from the relay, see if the circulator stops. A volt meter is helpful for troubleshooting🤓
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Jamie Hall
    Jamie Hall Member Posts: 24,612
    I wish you'd disconnected the hot lead instead of the neutral... I really wish you had...

    If the boiler heating elements are off, it's not generating heat, and they should have turned off automatically if it had gotten too hot.

    It may well be a welded relay, or it could be any number of other failures in the system. Without probing the board, it would be impossible to say. Is it repairable? Only maybe. Sometimes -- if you can find the faulty component -- it can be replaced.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Beakster
    Beakster Member Posts: 7
    Hi. Thanks for reply. I have a multimeter here.  The relay is inside the control module so I'm not sure what I can do to diagnose it.

    How would I diagnose a zone valve end switch? All the zone valves appear closed.  Each zone valve is connected to the module with 4 wires.
  • Jamie Hall
    Jamie Hall Member Posts: 24,612
    It's simple enough. Determine which two terminals on the zine valve are power, and which two are the end switch (note that some zone valves only have three terminals -- one is common). If the zone valve is closed, the end switch should show an open circuit (you may have to disconnect one terminal, depending on the rest of the wiring) If the zone valve is open the end switch will show a closed circuit.

    Caution: find out if any of the terminals are live before you play, and if in doubt turn off the power.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England

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