Wireing to central unit?

Discussion in 'HVAC Heating & Cooling' started by Giles, Dec 16, 2009.

  1. Giles

    Giles Retired tool & Die and Mechanic

    Messages:
    112
    Location:
    N.W. Alabama--Florence--
    I have a 5 ton Carrier heat pump that is about 10 years old. It is a split unit with backup heat. I have only lived here for about two months and the previous knows nothing about the unit. The installers have gone out of business.
    In my breaker box there are three separate supplies for the system.
    One 60A breaker goes to the outside unit and is marked "heat pump"
    Two 60A breakers go to the inside unit and one is marked "central unit" and the other is marked "electric heat".
    I can't understand why there are two breakers feeding the inside unit. Would a single 60A breaker supply the fan motor and the emergency heat?
    If I don't need two breakers, I could use one as the power supply for a welding recepticle that I plan to install near the inside unit and it would save me a lot of work and expense.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,152
    Location:
    New England
    The heat pump itself probably doesn't need 60A - there should be a data plate on it. It's probably more like 20-30A, and maybe even 15A (but at 10-years, the efficiency it probably wants something like the 20A). The air handler is primarily just a fan with the exception of the heating elements. It might be powering some from the 'internal', standard wiring, and the 'extra' heating elements are off the second breaker. So, of the three breakers, the only one that can probably be downsized is the one for the heat pump itself. The only way to know is to open them up and look at the data plates, and, since you don't need to install all of the possible heating elements in the air handler, see what's there, and then determine if it will still be okay if you downsize a breaker. I doubt you'd be able to eliminate one, and downsizing doesn't help you if you need more panel space.

    I don't think code would allow you to tap off that feed, but I'm not sure.

    Best to run a new circuit.
  3. Giles

    Giles Retired tool & Die and Mechanic

    Messages:
    112
    Location:
    N.W. Alabama--Florence--
    Thanks for your answer--- I talked to a service man and he said the unit probably had two separate heating strips and one breaker would not be enough. He also said that the unit was about 7 years old.
    I guess I will leave it alone.
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