Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Best way to determine which thermostat controls which zone valve?

redubshank Member Posts: 1
Florida native that just moved to Colorado so I am a total novice to heating systems. The house we just purchased has 2 of the thermostats hooked up in a weird way(there are a total fo 5 thermostats but just these two are in question). It's a hydronic baseboard system. Basically the thermostat in the office upstairs controls the downstairs dining room/kitchen baseboard heaters and the thermostat in the dining room controls office and extra bedroom baseboard heaters. It's a terrible design since it can create a situation where the thermostats never turn on or always stay on depending on what heats up first. I also suspect it's not on purpose.

In any case, what I am getting what do you guys think is the best way to determine which zone valve goes to which thermostat? Nothing is labelled. Would shutting all thermo stats off and just using a volt meter be sufficient? Anything important I need to be aware of?



  • Big Ed_4
    Big Ed_4 Member Posts: 2,818
    Shut off all thermostats and raise one at the time

    There was an error rendering this rich post.

  • Jamie Hall
    Jamie Hall Member Posts: 23,536
    Nothing is labelled. I'm getting used to that...

    It is, perhaps, not so much a question of which thermostat controls which zone valve as it is a question of which zone valve turns on the heat to which space. You have to identify that first! So -- turn one of the thermostats up (leave the other one way down). Then go to the heating system and see which zone valve is open. That's the zone valve controlled by that thermostat. Then go back upstairs and see which zone is heating. That's the zone fed by that zone valve. Now go back down and attach a label to the zone valve -- and another label to the thermostat wires attached to that zone valve. Do the same with the other thermostat.

    Now, using your labels, just switch the wires like for like -- that is, the wire pair which says "office" to the zone valve which says "office"...

    Do this with the power off...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Zman
    Zman Member Posts: 7,588
    Turn them on one at a time, note which valve opens, then check to be sure the baseboards heat up in the correct room.
    Zone controllers like the Taco ZVC sure clean up the wiring and make troubleshooting simple.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein