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Wi Fi Thermostats

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guardian
guardian Member Posts: 3
in Thermostats and Controls
So most currant systems carry the "C" or common wire for new wifi set ups. So which is the correct wiring for an older or currant 2 wire oil fired systems. I was told install 2nd transformer remove jumper from R& RC . Connect heat to R & W. Common from new trans to C and power side of trans to RC. This info tech support. Is this Correct? have installed other wi fi set ups but this is first Or test run on an 2 wire oil fired system. This is a hot water bb system single zone cold start.

SWEI

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  • Bio
    Bio Member Posts: 278
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    Yes that will work, that's how I have it
    guardian
  • Zman
    Zman Member Posts: 7,569
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    I am not sure why you need a second transformer. You just need to get a common to the t-stat.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    guardian
  • guardian
    guardian Member Posts: 3
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    Zman . Where do get a common wire from a Honeywell aquastat L8124A?
  • Zman
    Zman Member Posts: 7,569
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    I don't have one in front of me. From the looks of the schematic,I don't think they gave you a terminal or a wire to cut into. You would probably have to solder onto the board.
    That was not very nice on Honeywell's part...
    If you add a tranformer to the system be sure you wire it to the same 120 circuit as the other one or you can end up 48 volts rather than 24 volts. I knew a guy that did that, it lets all the smoke out. LOL.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • ratio
    ratio Member Posts: 3,627
    edited January 2016
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    That 48 volts is why they're having you pull the jumper from R-RC. That basically separates the two functions, power to the stat on RC(ooling) & C, R (think RHeat) & W.

    Also not getting the 48 volts depends not only on the right circuit, but the right polarity on that circuit as well - if it's backwards you still get 24 + 24 volts...

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