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  1. #1
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    Reznor garage heater sizing

    I am getting ready to install a Reznor UDAP heater in my garage and Iím debating between the 45k & 60k units. I have a slightly oversized 3 car attached garage that measures 33x24x11. The walls, ceiling and garage doors are insulated, but I donít know the R values. I can say that one of the 24ft walls border the house and half of the 33ft wall also borders the house. The remainder are exterior walls. There are two insulated garage doors, one is 16x7 and the other is 9x7. These doors are from the 90ís and are pretty thin. Nothing like some of the insulated doors I saw at a garage door company yesterday. There are two windows in the garage along with one standard maintenance door.

    I live in Northeast Ohio and want to keep the garage heated through the winter to 50-55 degrees, but also want to bring it up to 65-70 degrees when working out there. I donít want to wait for an hour for it to come up to temp. The calculations show a heat loss of about 36k, so a 45k BTU, 83% efficient unit should be just enough, but Iím debating putting in a 60k BTU unit just to be safe. What are your thoughts. Do you think the 45k unit would be fine? Do you think the 60k unit would be overkill? I donít want to get into an issue with short cycling the 60k unit and cause issues with it. I also donít want the 45k unit to run all the time.

    What do you think?

  2. #2
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    I dont have a huge problem with oversizing garage ductless heating, as long as it's not a triple oversize.... blatantly huge.

    I wold always go the next step up in size mainly because one wall is not "fixed". The "walls" go up and down creating massive heat losses. We call these "overhead doors".
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

    Jtrammel - "Iím going to sell hvac systems derp derp derp"
    BBeerme - "every time he opens his mouth, he reminds me of a cow without the fart bag."

  3. #3
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    Thread Starter
    Thanks.

    I also have a question about wiring the unit. The on-line manual says the ďfull load ampsĒ is 2.4. It also says the ďMaximum Over Current ProtectionĒ is 15. It requires a minimum temperature rise rating of 60C. What it doesnít say in the manual is the wire size and type. It says the minimum wire size will be listed on the unit, which I donít have yet, but I want to start pulling wire to get a little ahead of the game.

    My question is what size wire & breaker do I need? Iím guessing the Maximum Over Current Protection value dictates the breaker size. Is this correct? If so, would 14/2 with ground work for the wire?

    The wire will be run from my breaker panel in the basement, through an adjoining wall between my garage & family room, and then terminating in the garage. Do I need any special wire since it will be run in the basement and out in the garage? Not sure if there is a moisture requirement for potentially damp environments.

  4. #4
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    14/2 w-G will be fine for that heater if it uses a 15 amp circuit breaker
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

    Jtrammel - "Iím going to sell hvac systems derp derp derp"
    BBeerme - "every time he opens his mouth, he reminds me of a cow without the fart bag."

  5. #5
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    Thread Starter
    Quote Originally Posted by HVAC_Marc View Post
    14/2 w-G will be fine for that heater if it uses a 15 amp circuit breaker
    Not sure if it uses a 15 amp breaker. That's part of my question. It say the Maximum Overload Protect is 15. Does this dictate the breaker size?

    The length of the wire run will be between 50-60 ft. Does this cause any concern from a voltage drop perspective?

    Thanks

  6. #6
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    Quote Originally Posted by jjscott View Post
    Not sure if it uses a 15 amp breaker. That's part of my question. It say the Maximum Overload Protect is 15. Does this dictate the breaker size?

    The length of the wire run will be between 50-60 ft. Does this cause any concern from a voltage drop perspective?

    Thanks
    MOP 15 means a breaker or fuse not larger than 15 amps.

    Voltage drop wont be a problem.
    Experience - knowing when to get the hell out of the way and plug your ears. "Don't be a sissy. Turn it on!"

    Poodle Head Mikey - "the world is well populated with the unknowing and the uncaring and the stupid."

    Jtrammel - "Iím going to sell hvac systems derp derp derp"
    BBeerme - "every time he opens his mouth, he reminds me of a cow without the fart bag."

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