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  1. #1
    Join Date
    Mar 2016
    Location
    Massillon, OH
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    How to convert from aluminum to copper before air handler

    Hi,
    Im a newer residential hvac installer and Im installing my first heatpump airhandler and aux heat. ( so far my installs have been typical split systems )

    The current air handler has a 100 amp breaker in the main breaker with aluminum wire to the existing air handler.

    The new air handler says " DO NOT CONNECT ALUMINUM WIRE DIRECTLY TO THE AIR HANDLER " follow NEC for properly converting to copper.

    The new air handler / aux heat calls for a 50 AMP max breaker for a 10 kw aux heat.

    Im assuming I get a dual breaker like subpanel and tie the aluminum to the lugs, and put in a 50 amp breaker to copper #6 into the new unit?

    Or how do I convert from the huge 100 amp aluminum wire to #6 copper and a 60 amp breaker?


    Thanks!
    Joe

  2. #2
    Join Date
    Feb 2008
    Location
    Western Wa.
    Posts
    3,542
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    Quote Originally Posted by WarstlerFurnace View Post
    Hi,
    Im a newer residential hvac installer and Im installing my first heatpump airhandler and aux heat. ( so far my installs have been typical split systems )

    The current air handler has a 100 amp breaker in the main breaker with aluminum wire to the existing air handler.

    The new air handler says " DO NOT CONNECT ALUMINUM WIRE DIRECTLY TO THE AIR HANDLER "follow NEC for properly converting to copper.

    The new air handler / aux heat calls for a 50 AMP max breaker for a 10 kw aux heat.

    Im assuming I get a dual breaker like subpanel and tie the aluminum to the lugs, and put in a 50 amp breaker to copper #6 into the new unit?

    Or how do I convert from the huge 100 amp aluminum wire to #6 copper and a 60 amp breaker?


    Thanks!
    Joe


    You answered your own question
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  3. #3
    Join Date
    Feb 2014
    Location
    Phoenix Arizona
    Posts
    944
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    How to convert from aluminum to copper before air handler

    The best scenario would be using the terminal blocks in a panel/disconnect.

    Any time conductors of dissimilar metals touch(most terminal blocks are aluminum or steal or both, most wires are copper), you should be using this.

    If you have to splice the two in a junction box or other place without terminals, I like these.

    The option I like the least is just to fill a wire nut with the inhibiter paste. They sell pre-filled ones.

    Trying to join aluminum with other metals sets off some pretty nasty dissimilar metal corrosion, which is caused by electrolysis. Aluminum to copper in particular is problematic. The more noble copper becomes a cathode and the aluminum becomes a sacrificial anode. A expanded, fairly resistive layer is formed around it as it sheds itself. This higher resistance can create a lot of heat and (especially in plastic contained joints) can lead to a fire.

    This actually happens all the time, and isn't just a building code issue. I found a burnt out junction box just last week, where one of our install crews tried to splice 6Awg aluminum to 10awg copper with normal wirenuts. Only 4 months later and I'm there on a no cool, looking at what should have been an attic fire. It's a miracle that the thing burnt itself out before it escaped the metal Justin box. It was nailed to an old truss that was covered in pitch. I cut the whole melted thing out and put it on the install managers desk.

  4. Likes Pajal liked this post
  5. #4
    Join Date
    Mar 2016
    Location
    Massillon, OH
    Posts
    11
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    Thread Starter
    So this is what I came up with. The aluminum into the subpanel, then out to the unit copper.

    1) Does this look like a proper way to adapt aluminum to copper?

    2) Does this box need a bonding solid copper line to the panel or is just the aluminum twisted ground in the aluminum wire adequate?

    3) I came out of the 50 AMP breaker in my subpanel and into the 60 AMP breaker thats on the front of the "toaster" and sticks out of the front of the unit. Then the manual showed connecting the small 14 gauge 220 for the air handler to the 60 AMP breaker on the aux heat. Thats the way I connected it, but looking back, why would the air handler be tied to a 60 AMP breaker? The manual shows connecting the air handler to a 15 AMP 220 breaker if no aux heater is installed. But if an AUX heater is installed connect the wires to the 60 AMP breaker on the aux heat. This doesnt seem safe to me. It seems to me that I should have the toaster on the 60 amp breaker and run a separate 220 to a 15 AMP for the actual air handler wiring. Is this common practice to connect the airhandler 220 to the aux heat breaker like the wiring diagram and manual say?

    Thanks for the help! Like I said this is my first year installing and I do mostly gas furnaces and this was my first heatpump with aluminum wiring. I want to do it by the book and safely.

    Joe

    Box without breakers.jpgWith wire and breaker.jpgFinal Pic.jpg

  6. #5
    Join Date
    Mar 2014
    Location
    Charlotte, nc
    Posts
    261
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    Any prior experience? I saw your other post about the electrical questions and it seems your a little inexperienced to be installing units by yourself do you buy your units online?

  7. #6
    Join Date
    Jul 2001
    Location
    maryland
    Posts
    1,408
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    Use clear taps, they sell them at electrical wholesalers, you have to know what wire size you want
    Saving the world...one service call at a time.

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