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burnham steam boiler # IN7SNC-ME2

Dan_43
Dan_43 Member Posts: 57
in Strictly Steam
My old thermostat is 2 wire. I want to put new WiFi theromostat on the boiler. What do I use for the (C) common wire. from what I can see from the schematic brown to W, blue to R and yellow would become my C. is this correct? does anyone have a recomedation for a wifi thermostat

109A_5

Comments

  • Big Ed_4
    Big Ed_4 Member Posts: 2,983
    Yes ,the yellow wire, coming from the transformer would be the common . Add a 3amp fuse on the blue to protect the transformer from shorts .

    There was an error rendering this rich post.

  • Dan_43
    Dan_43 Member Posts: 57
    Thank you for confirming my thinking. And why do you think I would need a fuse on the blue, now because I'm tapping the yellow?
  • 109A_5
    109A_5 Member Posts: 1,478
    Hello @Dan_43,
    The Blue wire is the 24 VAC Hot wire leaving the transformer, the Yellow wire is grounded.
    It is just good practice and you are adding more load and wires to the system, more potential for issues.
    If your new toy has a meltdown the fuse may save the transformer.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System

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