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  • Radiant Floor Heat

    I am remodeling a bathroom and my customer would like to get rid of his steam radiator and install radiant floor heat. Running a new circuit to the electric panel however is impossible. There is a window air-conditioner in the bathroom on a 220 circuit. Which of course won't be used in the winter when the heat is needed.

    My question is if its possible to use the air-conditioner circuit for the floor heat. The heating pads for this size (4'x4' max) are rated 120V... there is a thermostat control for the floor thats rated for 120/240 but the small pads are 120. Can I use this control with a 120 pad on 220 circuit?

    Clear as mud?

    Thanks in advance!

  • #2
    Re: Radiant Floor Heat

    power here in the US. split phase for residential.
    the 220 volt circuit can supply the controller and the pad but you need to know what you are doing on this
    this needs to be done properly by an electrician
    if you are not an electrician please call one on this
    shooting the s*** is a lot more fun when you use hollow points (much more splatter)

    coffee hell gimme booze!!!

    Comment


    • #3
      Re: Radiant Floor Heat

      Probably not. The breaker is sized for the AC and likely not sized for your circuit too. If an older 3 wire ckt, you cant use it. Moreover, nearly always a radiant heat mats need GFCI protection (which you probably don't have). The listing instructions usually call for a dedicated (individual) circuit.

      I agree with the others, hire an electrician and have the piece of mind of knowing it's done right.

      Also, the wiring methods need to be compliant. (it would suck if the inspector made you rip up the new floor!)

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      • #4
        Re: Radiant Floor Heat

        thanks i forget to mention the breaker
        shooting the s*** is a lot more fun when you use hollow points (much more splatter)

        coffee hell gimme booze!!!

        Comment


        • #5
          Re: Radiant Floor Heat

          Oullet makes a 220 volt radiant mesh. Their controller also has GFCI protection internal to the unit. The breaker would have to be changed out to the size required by the mesh. I think the 220 volt version starts above 60 sq ft.
          ~~

          ... it was plumbed by Ray Charles and his helper Stevie Wonder

          Comment


          • #6
            Re: Radiant Floor Heat

            No, I don't think this will fly;
            The AC wall unit is most likely a dedicated outlet and is allowed to be rated at 80% of the branch circuit. If you add the radiant heat to this outlet the AC is now only allowed to be rated at 50% of the circuit rating. Example; Your ac draws 16 amps and is on a 20 amp breaker with #12 wire. But now, you would need to wire a 40 amp circuit just to add the heat, which would require #8 wire!
            See Art 440.62 of the NEC
            There is an exception that would still allow the 80% rating, but it would need to be electrically interlocked to prevent simultaneous operation.
            Last edited by johncameron; 04-08-2013, 02:01 AM.

            Comment


            • #7
              Re: Radiant Floor Heat

              I was under the impression that the AC would be abandoned. It would have to be one or the other, not both.
              ~~

              ... it was plumbed by Ray Charles and his helper Stevie Wonder

              Comment


              • #8
                Re: Radiant Floor Heat

                Originally posted by johncameron View Post
                No, I don't think this will fly;
                The AC wall unit is most likely a dedicated outlet and is allowed to be rated at 80% of the branch circuit. If you add the radiant heat to this outlet the AC is now only allowed to be rated at 50% of the circuit rating. Example; Your ac draws 16 amps and is on a 20 amp breaker with #12 wire. But now, you would need to wire a 40 amp circuit just to add the heat, which would require #8 wire!
                See Art 440.62 of the NEC
                There is an exception that would still allow the 80% rating, but it would need to be electrically interlocked to prevent simultaneous operation.
                right Im used to installing the combination ac and heater units that are used in some of the offices. and hotel rooms
                these were wired using #8 wire for the larger ones and 10 for the smaller
                these were usually equipped with interlocks
                shooting the s*** is a lot more fun when you use hollow points (much more splatter)

                coffee hell gimme booze!!!

                Comment

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