I just purchased an MBR1200AA1 with 20kw heat strip from goodman to replace an old furnace from the 70s thats recently gone beyond simple repairs.

Want to install it but came across 2 breakers, one with red/black wires, a second with yellow/blue wires.

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I assume its going to need two seperate breakers in the panel and 2 runs of copper but unsure of how to connect those breakers on the unit. The previous unit was dummy proof.

  • 2
    Wow the instruction sheet is messy. What about the original furnace, how was it wired? What was its kilowatt rating (BTU would suffice). Is this a conversion from fuel to electric? Mar 10, 2023 at 19:42
  • I presume it came with some sort of installation diagrams...? Which country? (In the US I would expect it to want 240V, which is a linked pair of breakers.)
    – keshlam
    Mar 10, 2023 at 19:45
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    What kind of furnace did you have before? If it was something other than electric you may not have enough power available. 20kw is 80a, likely needing 100a of breakers. Most people don't have that much spare capacity Mar 10, 2023 at 19:49
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    110A of breakers actually. That would overload even a 200A service if the rest of the house is all electric, I suppose they could simply provide power to the red/black breaker and don't hook up the other one. It would run at about 60% power. Though, right now Technology Connections is halfway through a video series on new ways to address THIS EXACT PROBLEM, so I'd advise thinking such thoughts and/or waiting for the 2nd video to drop before rushing out and getting a 400A service lol. Regardless, it's solvable. Mar 10, 2023 at 19:55
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    If this is a replacement for a gas furnace, it is absolutely crazy. If it is a replacement for another giant toaster, now is the time to consider whether putting in a heat pump is worthwhile. The upfront cost for a heat pump will be several thousand dollars more (because an air handler is an air handler, and toasters are cheap but compressors are not). But you could save a lot of money on electricity over the course of a few years. Mar 10, 2023 at 21:13


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