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window A/C

user-429284's picture

rewiring house. She uses an OLD window a/c unit. would like to allow for upgrade to a/c. (possibly allowing for central air run using same wire... or at the very least for a larger / more efficient window unit). question: 1) dedicated circuit 2) #12, or #10?




Dedicated circuit -- 4 (post #207238, reply #1 of 4)

Dedicated circuit -- 4 wires.  (One will be unused at 120V.)  #12 should be fine for a window unit, unless she gets a monster.  You should probably pull a new wire for central air -- it will need to terminate outside near where the compressor would be located.

Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

What size? (post #207238, reply #2 of 4)

Without knowing what size unit she is running, what the new one may be, or what size central is needed it is incorrect to reccomend wire size.  A 120V/20amp or 240V/20amp unit will need a #12 wire size.  Most central units require a 30 amp 2 pole breaker so the wire size is #10.  Some larger window shakers are also 30 amp, so it is imperative that you know whatthe load will be.


I understand wanting to size for a central a/c unit for the future.  In that case I would run the larger #10 wire to a j-box near the location of the expected central unit and then the apprpriate size wire to the window unit. Use the correct isze breaker for the applance and the wire size.  Remember the breaker is to protect the wire, not the appliance.

Look into mini-split that (post #207238, reply #3 of 4)

Look into mini-split that will also run as heat pump.  It may pay for itself in 4-5 years (or even less depending on elec rates and climate wherever you are).  Only as a very last resort would I ever install a window shaker, all they are good for is helping remove old loos glazing <G>

A 2T 19 seer HP/ac will run off a 20A 240V circuit, a 3-1/2T off a 30A circuit.  Good inexpensive alternative to central unit if ducting not already in place.

I just install a 19 Seer inverter type mini-split at sons house, was amazed at how quiet those new type unit are.  Watched the meter after install -- First few days at 35 deg outside and kept the small building (800 sq ft) toasty for 9 kw-hrs per day (includes lights but nothing else connected yet)  

AirConditioner wiring (post #207238, reply #4 of 4)

THANKS to all of you.

Have a Blessed '13.