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WiFi thermostat with Weil Mclain boiler

Good evening guys. I'm trying to install a wi fi thermostat with my Weil Mclain boiler. I searched in the forums here to no vail. Any word on how to add a common wire for this boiler. I dont want a wal wart. Thanks.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 19,141
    Somewhere on or around your boiler there is a transformer. One terminal on the low voltage side is the common; the other is hot 24 volts. You need to identify which one is the common side and run your third wire from that to your thermostat.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • HVACNUT
    HVACNUT Member Posts: 4,622
    If you tell us the model of the boiler, we can better lead you in the right direction. If oil fired, 1 zone with a triple aquastat, it will need a separate transformer and an isolation relay. Most gas fired boilers, atmospheric or mod con will have an internal transformer you can use or a zone control board.
  • fabaze12
    fabaze12 Member Posts: 21
    @HVACNUT

    I hope that's what I need to show so you guys can help me with this task.

    Thanks.
  • HVACNUT
    HVACNUT Member Posts: 4,622
    @fabaze12 yes that helps but...
    Can you post a pic of the whole boiler from about 8 ft away?
    Steam or water boiler?
    We'll see if there's anything with a transformer you can use.
    7 sections? Really big house or oversized boiler.
  • fabaze12
    fabaze12 Member Posts: 21
    @HVACNUT, its a 3 family. 1st and 2nd floor is about 2700 sq ft altogether. 3rd floor is about 450 sq ft but the lone radiator sits in a room about 150 sq ft.
  • HVACNUT
    HVACNUT Member Posts: 4,622
    OK. You don't have a common on the system that can be used. The low volt from the thermostat goes directly to TT on the burner primary. A switching relay like a Taco SR501 will need to be installed by a qualified tech.

    On a side note, the boiler is rated at 2.00 GPH but I see on one service card the nozzle is 1.25 GPH. It's possible the pump pressure has been increased to bring it up but I would find out.