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Garage heater electrical question

5 years ago

I am planning on installing a mr heater Big Maxx 80000 btu heater In my garage. I was wondering for the power supply (which requires 115 volts ac) if I could run it on the same circuit as the 20amp breaker that consists of 5 outlets On that side of the garage. My plan was to run 12/2 wire up to the spot for the heater from one of the other outlets. otherwise, would it be okay to tie in to the line/power side of the lights which are on a 15amp circuit? note, I live in Wisconsin.

thanks in advance

Comments (8)

  • 5 years ago

    Since that’s a gas heater, it doesn’t require much electricity to power it... 2.3 amps according to the manual. That’s less than a 300 amp light bulb. So there should be no problem tying it in to another circuit. You can handle 1800 watts on a standard 15 amp circuit (14 gauge wire) and 2400 watts with 12 gauge wire. This situation is like any other circuit: if you don’t hook up more of a wattage load than the circuit can handle, it won’t trip the breaker. And those laws of electricity are the same for Wisconsin as for the rest of the world. ;-)

  • 5 years ago
    last modified: 5 years ago

    Perfect, sounds good. Thanks for the getting back to me! Just wasn’t sure if code requires it to be on it’s own circuit.

  • 5 years ago

    My first thought is that you must have a really big garage if you need 80k BTU to keep it heated; however, you didn't really explain the size and insulation in your garage.

    Also keep in mind that a byproduct of burning natural gas or propane is water/humidity, so many heaters of this type will raise the humidity in the garage when its running (but I have no experience with the Big Maxx). Some folks have found this to be a problem with rust on tools. Also ensure your house gas line is sized properly to handle 80k at the same time you are heating your house, heating hot water, etc. Sometimes you need to upsize the house gas line or pressure to handle a heater this size.

    Bruce

  • 5 years ago

    Thanks Bruce For the input. I have about 1200 sqft to heat. The heater is definitely overkill but I got it from a family member for cheap thats only 2 years old. The walls I insulated with r-15 and the ceiling already had 17 inches of blow in insulation. I guess I didn’t think about the extra moisture. My dad has a different brand in his workshop and hasn’t really had any problems but I’ll look into that with this brand. I plan to keep the garage at about 40 during the winter and bump it up to 60-65 when I’m working in there.

    our furnace is the only gas appliance in the house and that has a 1/2” pipe running to it. A buddy of mine that works at Xcel said it shouldn’t be a problem adding a T and a regulator at the new heater.

  • 5 years ago

    Where I live its more common to have a 3/4" line coming off the meter, and then use 1/2" feed to each appliance.

    When I submitted permits for my renovation they calculated my 3/4" line to handle about 170 cu ft per hour, and the BTU max was about 175 BTU/hr. I think a 1/2" line only handles about 1/2 the flow of a 3/4" line.

    Bruce

  • 5 years ago

    You should ask the code official in your municipality questions about code requirements. The code official makes the decision whether your installation is compliant or not.

  • 5 years ago

    For my permit I had to submit a "riser diagram", which showed all the gas pipe sizes, BTUs for each appliance, and the physical layout of the pipes (T's etc.).

    Bruce

  • 5 years ago
    last modified: 5 years ago

    sounds good guys, I will contact the city in the the morning and double check. I only need to run about 20ft of rigid pipe to the heater in my garage. my house is a new build in 2020 and they ran that flexible gas tube from the meter which is 1/2” the whole way. So I will make sure I have enough flow to handle the heater. Thanks for all the help