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Weil-McLain Control \ Wirsbo / Uponor compatibility

tomswell Member Posts: 2
I'm working with Wirsbo / Uponor zone control module that has a solid state switching output "ES"
stated to be totally isolated. Although I see 5 millivolts between leads.

New Weil-McLain high efficiency boiler requires "dry contact" signal ,
they certainly don't want 24V. what about 5 millivolts ?

do I need to add relay or not ?

Both manufactures pass the buck to the other and are not helpful.


  • FrankB101
    FrankB101 Member Posts: 16
    It should not be a problem connecting the boiler directly to the control. The solid state switch is essentially a N.O. dry contact.
  • Jamie Hall
    Jamie Hall Member Posts: 23,441
    Um... sort of. I'd want to check for a voltage between either of the ES outputs and the boiler's control. The zone control output looks like a dry contact, in some ways -- but it's a triac, not an actual contact, and unless the grounds and hots on the two pieces of equipment are compatible, it's entirely possible that there may be some interesting problems...

    I'd use a relay, to get a real dry contact. But I'm a conservative sort of duck...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Zman
    Zman Member Posts: 7,573
    The 5mv is probably stray current. Can you post the diagram?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein