Click here to Find a Contractor in your area.
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/.

Switch Relay/Circ Pump not listening to Stat

Heat_newb
Heat_newb Member Posts: 1
Hello -

I have a Weil-McLain P-WTGO-6 (Series 3) Oil-fired Water Boiler running baseboard radiant. I have a Taco SR504 Switching Relay running 4 Zones.

My issue is that zones 3 and 4 don't seem to be listening to their stats. Despite their set points being satisfied, the zone stays lit (RED zone indicator light) on the Taco, and I can hear the Circ Pump and furnace continue to run. They will continue to run in this manner even if I turn the Stats OFF. The only way I have been able to get it to stop is to disconnect one of the Stat wires where it comes into the respective zone on the Taco.

Thoughts?

Comments

  • hvacfreak2
    hvacfreak2 Member Posts: 500
    Does your unit have 2 or 3 terminals for each thermostat input ?
    hvacfreak

    Mechanical Enthusiast

    Burnham MST 396 , 60 oz gauge , Tigerloop , Firomatic Check Valve , Mcdonnell Miller 67 lwco , Danfoss RA2k TRV's

    Easyio FG20 Controller

  • JohnNY
    JohnNY Member Posts: 2,717
    Remove the thermostat wires and jumper the T-T (or end switch) connections on each zone. If doing that energizes the pump terminals and closes the X-X contacts, then your problem is in your thermostat/wiring.
    Contact John "JohnNY" Cataneo, Master Plumber
    in New York
    in New Jersey
    for Consulting Work
    or take his class.
  • hvacfreak2
    hvacfreak2 Member Posts: 500
    Either way the question is weather or not voltage is present on the input wires. If it is a 2 wire input remove one of the wires and measure it's voltage to 24 volt common ( power input toward the left of the relay board has a common ). If there is no voltage present on that wire than I would suspect the relay board. If there is voltage present than the problem is in the wiring or the thermostats. If this is a 3 wire input use the W wire for testing.
    hvacfreak

    Mechanical Enthusiast

    Burnham MST 396 , 60 oz gauge , Tigerloop , Firomatic Check Valve , Mcdonnell Miller 67 lwco , Danfoss RA2k TRV's

    Easyio FG20 Controller

  • HVACNUT
    HVACNUT Member Posts: 4,084
    Are the thermostat wires for 3 and 4 from one cable? For example, zone 3 has red and white and zone 4 has green and yellow and they're from one cable and then split somewhere to there respective stats?
    With 2 zones constantly running but stop when you disconnect a wire from TT, it seems like a dead short on a 4 (or more) conductor cable. Hang any pictures lately? Or any work using nails or screws?
  • ratio
    ratio Member Posts: 2,872
    What stats are on the zones? Stats that use TRIACs to switch loads, as opposed to a relay, can fail conductive, analogous to the contacts of a relay sticking closed. They can also fail conducting in one direction only, i.e. appear in-circuit as a simple diode. They also are somewhat hard to diagnose, as they require a minimum load on the output side to operate—a modern high-impedance multimeter will show them as conducting regardless of the state of the device. A meter with a low impedance range, like the Fluke 116, will give you valid readings.