Recommendations heat pump wiring

[rmeade]

Greetings!

I plan to install a 1 Ton (12,000 BTU) heat pump. I want to install wiring now and install the heat pump later (work on the panel is required). I want to install the wiring now because the roof is open (to this one story cottage)- making the task easy. Heat pumps in this size seem to be either 115v 15amp current (25amp breaker recommended) or a 230volt 10 amp current (15 amp breaker recommended).

What sort of wiring would be recommended for the 115volt system (10 or 12 gage, three wire) and, alternately what would be recommended for the 230 volt system (12 gage 4 wire)? MrCool equipment seems attractive (4th generation, Energy Star Ductless Mini-Split: DIY-12-HP-WM-115C25) although there is a lot of other manufacturers that are also attractive.

Thanks for your help!

 

[mm08822]

Here is the chart from the manual. You need to wire to the Minimum Circuit Ampacity (MCA) spec'd by the mfr.
Use the mca values and ignore their wire sizes as somebody missed the boat for wire sizing.
(How could 19A require #12 and 18A require #10, etc......) You should be fine with 12-2, 10-2 if it makes you feel better. Get a 240vac unit.

 

[pcmeiners]

To add...
Maximum current of a 12k unit is usually around 12 amps. Minisplits might run at maximum until the desired temp is achieved, then use less, much less (unless under rated). A #12 is sufficient for all but the longest wire runs at 9k/12k. If uindoubt as to the capacity that will be installed later, possibly an 18k?, then prewire a #10.

 

[mike93lx]

My 2.5 ton units are on 12/2 nm-b with 25a breakers. That's probably what i would run in this case

Run 10/2 if you feel better

 

[rmeade]

Thanks for the replies.
MM0882: Why do you recommend the 240volt unit, So it looks like the 12nm-b would work there as well?

 

[mm08822]

Anytime I have the option of 240v, I would run it for usually a smaller wire size, lower voltage drop, allows for a longer length run without needing to upsize and possibly reduced light flicker to the rest of the home.

240v doesn't change the wire/cable required other than possibly smaller a size required. All power wiring is rated at least 300v and more predominantly at 600v.

These instructions are scary. Never heard of a "N" (nuetral) referred to as "Null". Maybe consider another mfr. What else is half-assed?

 

[rmeade]

Thanks for the responses!

 

[Highbeam]

The gen3 mr cool units had a similar chart with much more "normal" wire size requirements. Running 6 gauge for a mini is ridiculous.