New central AC system with heat kit issue

Old 05-03-18, 06:08 PM
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Join Date: Oct 2005
Location: Florida
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New central AC system with heat kit issue

I had a new central AC unit installed about six months ago. The inside unit is a BRYANT model FB4CNF024L00ADAA and the outside also a matching BRYANT unit.

My original central AC was a Rheem unit, and we used the existing wiring. The inside unit connected to a double 30A, the outside unit double 25A. I believe the wiring is #10 but I am not absolutely sure.

The unit included a 5KW "heat kit", even though in South Florida we rarely need heat, but once in a blue moon who knows.

So recently I heard some rattling noise with the unit and it's still under warranty, so I called them to come out to take a look. The tech opened the cover up and there were some skinny silver pipes touching each other. He manually pulled some of these pipes further apart - saying they shouldn't be touching each other and he couldn't understand why they were. Anyway that problem is solved.

He then looked at the set of breakers on the actual air handler unit and he said hmmm, why do you have a pair of 60A breakers here? I said I don't know. He looked a bit closer and he said he thinks I have a 10KW heat kit instead of a 5KW. We went to the main panel and the air handler is connected to a pair of 30A breakers.

He said this could be a fire hazard because the breakers on the heat kit needs to match the breakers on the panel. He suggest that I change the breakers on the panel to 60A. I said I do not have the wiring for 60A, the wiring is either #8 or #10 and I think it's #10.

He then said there is a problem. They need to change the heat kit to a 5KW but he thinks that comes with a pair of 45A breakers. So he said I have to change the panel to a pair of 45A.

I am not sure I am following it 100% here, if the heat kit is 5KW or 5000W, 5000W divided by 240V = 20.8A, so a pair of 30A breakers should suffice. Why 45A? Wouldn't changing the breakers on the unit and at the panel to 45A be a problem due to undersized wires?

Old 05-03-18, 07:22 PM
Geochurchi's Avatar
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Hi, if the conductors are #10 you can not increase the breaker size, you are correct that if the heat section is 5KW then the existing circuit should be fine, it should also state on the unit name plate the size of the conductor s and max breaker size.
Old 05-03-18, 09:23 PM
PJmax's Avatar
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There really is nothing dangerous about the setup. The breaker will just trip when the electric heat is activated.

You need to get the installer back to remedy that situation. Actually.... he may already have.
It's not a single 10K heating element. It's several smaller ones. He may have wired only one element to run. That would be ok.

What he's done should be indicated on the unit for future servicing.

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