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-   -   An HVAC electrical ? (http://www.diychatroom.com/f18/hvac-electrical-29881/)

737Pilot 10-13-2008 04:43 PM

An HVAC electrical ?
 
Ok, I am just looking for ballpark figures as I know I can't get an exact answer since I don't have a brand of HVAC yet. But I am curious as to how much amperage a 5 ton unit will use with the air handler and condenser.

Thanks.

gp_wa 10-13-2008 05:02 PM

My 2 ton HP system pulls about 9 amps total on second stage heat, a bit less on second stage cooling. Those are real numbers at the sub panel feed line with an amp clamp.

ScottR 10-13-2008 05:10 PM

~25A @ 240V running load .. This is a generator sizing guide, but lists approximate loads for AC units (PDF!) http://www2.sea.siemens.com/NR/rdonl...zing_guide.pdf

micromind 10-14-2008 12:36 AM

I'd say around 25 to 30 amps.

When you get the unit, or at least its spec's, it'll most likely list a 'minimum circuit ampacity', or MCA. This determines the wire size.

It will also list a maximum fuse or breaker size. This listing is almost always over the current rating of the wire. HVAC, motors, and welders are some of the few instances where a breaker can be rated higher than the wire. Unfortunately, a lot of inspectors don't know this, and have to be led through the codebook.

Most likely, it'll need either an 8/2 or 10/2. Two hots plus a ground, no neutral.

Rob

beenthere 10-14-2008 09:00 AM

13 SEER, Less then 40 amps combined.

The average 5 ton 13 SEER OD unit will need a 8/2 with ground.

10/2 would not meet min circuit requirements of outdoor unit.

J. V. 10-14-2008 01:24 PM

Quote:

Originally Posted by gp_wa (Post 171848)
My 2 ton HP system pulls about 9 amps total on second stage heat, a bit less on second stage cooling. Those are real numbers at the sub panel feed line with an amp clamp.

Those readings sound awful low to me. And if you mean "heat strips" for second stage heat it definitely is wrong. 9 amps.
I would check it with another clamp.
When you get your new unit, it will have all the requirements on the name plate. And if you know what you are getting, you can always get the specs in advance from the supplier.


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