Air Handler Wiring


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Old 10-30-22, 02:43 PM
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Air Handler Wiring

I am installing a MrCool heat pump. For the outside unit I am planning to run 10/2 to a 40amp breaker. With a 60amp non-fusible disconnect.

My main question is on the air handler. I attached the name plate. I am gonna use the 15kW heater accessory. MCA for 240V says 59/28. And max breaker says 60/30. I’ve never seen 2 numbers so I’m wondering what they mean.

The heater kit has 2 breaker at the air handler and it says I need to run two lines of power. It might be saying 59 amps total or 28 per line and same with the breaker?

My thought is I would run 2 lines of 8/2 off 30 amp breakers. Those would connect to the air handler breakers. Do I need a disconnect at the air handler if it has breakers in it?



Outdoor unit

Air handler

Indoor unit wiring

Wiring for whole system
 
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Old 10-30-22, 03:12 PM
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Welcome to the forums.

10-2 is borderline as it's rated for 30A and your MCA is 35A.
If the condenser is more then 50' from the panel.... upside to #8.
The 40A breaker and 60A disconnect are fine.

Your air handler requires three feeds. One for the blower and controls and two for the heat.
They call for minimum circuit ampacity of 28A. Technically one half of 15k = 7.5k or 32A.
#10 is rated for 24A continuous load.
#8 is rated for 32A continuous load.
I would consider this a continuous load which means the wiring must be 2x#8 NM/b

If there are no breakers at the air handler then you'll need disconnects there too.
 
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Old 10-30-22, 05:23 PM
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I agree. You need to run #8 to the outside unit.
 
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Old 10-31-22, 04:46 AM
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Thanks for the replies. I will run #8 to the outside even though its only 20 feet to the breaker.

The below is from the air handler manual. It says since I am installing the heat kit, I don't need an additional line of power for the air handler itself. 2 runs of 8/2 off 30 amp breakers would still be fine? There is a 60 amp breaker connected to the heat kit.


air handler manual

heat kit breaker
 
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Old 10-31-22, 05:10 PM
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With that kit you just need 2) 240v supply lines.

Some of these companies don't put too much thought in their spec listings.
It says 60A which means 2x30A breakers. If the heaters draw 2x 28-32A ..... the breakers may trip.
 
 

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