We build. Pre-wire for mini split?

[TheRealMcCory1]

Hey guys, building a new external garage right now.

I'm curious about what pre-wiring should be done now to simplify installation of a ductless mini split system in the future.

Garage is 16'x22' with 9' ceilings and will be insulated with R-13.

Thanks for your help . Please let me know if I left something out. These systems are new to me.

Cory

 

[theoldwizard1]

What kind of service do you have running to the garage already ? I would hope it is at least 60A.

Pre-wiring for a mini-split is a good idea even if it doesn't happen for awhile. 10/2 NM should be adequate from the breaker box to where ever you plan on mounting the external unit. That would give you 240V at 30A.

 

[TheRealMcCory1]

Not wired yet, but it'll be 100A to the garage.

So I should put a 240V, 30A outside, you think.

Really appreciate the response.

 

[sevenzeronova]

Condenser unit size and type will dictate wire size and amperage. Better off running conduit to it and leave a pull wire in it. Other wise you are wiring for an unknown? Seems wasteful.

 

[TheRealMcCory1]

Condenser unit size and type will dictate wire size and amperage. Better off running conduit to it and leave a pull wire in it. Other wise you are wiring for an unknown? Seems wasteful.

Thank you seven. Good idea.

 

[sands35]

That is a small shop. Yes, you can put in conduit and pull later. Or you can put in a 30A disconnect and 12 gauge wire for not much more. Disconnects are in the $10 range and you will probably have some 12 gauge romex left over.

Likely you would only need 120VAC, 15 amps for a sub 10k btu mini-split.

Ceiling should be at least R-30, not R-13.

Is this a working garage or a storage garage?

 

[TheRealMcCory1]

That is a small shop. Yes, you can put in conduit and pull later. Or you can put in a 30A disconnect and 12 gauge wire for not much more. Disconnects are in the $10 range and you will probably have some 12 gauge romex left over.

Likely you would only need 120VAC, 15 amps for a sub 10k btu mini-split.

Ceiling should be at least R-30, not R-13.

Is this a working garage or a storage garage?

Thanks for the response, sands.

Appreciate the disconnect idea, I'll discuss that and the other alternatives with the electrician.

I had planned to do R-30 in the ceilings. R-13 is for the walls. I should've been more clear.

I'll be doing woodworking mostly. We have an attached 3 car garage that holds the car and other unnecessaries.
Thanks,
Cory

 

[mobiledynamics]

Not wired yet, but it'll be 100A to the garage.

So I should put a 240V, 30A outside, you think.

Really appreciate the response.

Pull a neutral. If memory recalls, the evaporator (indoor unit) is 120

 

[sands35]

Thanks for the response, sands.

Appreciate the disconnect idea, I'll discuss that and the other alternatives with the electrician.

I had planned to do R-30 in the ceilings. R-13 is for the walls. I should've been more clear.

I'll be doing woodworking mostly. We have an attached 3 car garage that holds the car and other unnecessaries.
Thanks,
Cory

Very cool.

Think about putting the outside unit in the afternoon shade (North or East side of the building.)

Your photo suggests that the garage door faces south and your house is on the right?

To make it simple, have your service entry go to the same wall, then your breaker box would be close to where the outside condenser unit would go. The putting in conduit later would be trivial.

 

[TheRealMcCory1]

Very cool.

Think about putting the outside unit in the afternoon shade (North or East side of the building.)

Your photo suggests that the garage door faces south and your house is on the right?

To make it simple, have your service entry go to the same wall, then your breaker box would be close to where the outside condenser unit would go. The putting in conduit later would be trivial.

You're correct on the direction of the sun. I was planning on putting the unit on the west side though. It's protected from the sun by my garage and a 6' privacy fence 5' from the base of the garage. The problem here is that it's a long way from the intended location of the service entry. The service entry is planned for the SE corner to minimize trenching, burrowing, etc.

Thoughts?

Thanks for being so helpful. As I believe I mentioned, I had planned on learning this as I went along, at my own pace. It's a bit of a blessing that the contractor is doing it for me as consideration for a small oops (save $) but it also means I have to harass the GJ experts a lot more.

 

[pseudorealityx]

If woodworking, be careful. Minisplits do NOT have traditional filters to stop that dust. You'll need to be vigil about making sure the unit can breathe.

 

[TheRealMcCory1]

If woodworking, be careful. Minisplits do NOT have traditional filters to stop that dust. You'll need to be vigil about making sure the unit can breathe.

Interesting. Thanks. I had not considered that. I'll do some research for possible solutions. Any ideas yourself?

 

[pseudorealityx]

Traditional bag dust collector is the best solution.

FWIW, woodworking and ANY HVAC system don't really get along. But minisplits are worse because their form factor doesn't allow a traditional filter. They typically just have a plastic 'strainer' type filter. Gets the big stuff, but that's about it.

 

[TheRealMcCory1]

Traditional bag dust collector is the best solution.

FWIW, woodworking and ANY HVAC system don't really get along. But minisplits are worse because their form factor doesn't allow a traditional filter. They typically just have a plastic 'strainer' type filter. Gets the big stuff, but that's about it.

Gotcha. I have a dust collector. I'm going to add a Wynn filter so that'll help. My wife will keep me on schedule checking the minisplit filter. She's good about that stuff ("reminding" me what I need to do).

Thanks.

 

[sands35]

Dust in the mini-split? eh - vacuum it out once a year. And buy a good dust collector.

You used to be able to buy just the filters for a DIY ceiling collector. Rockler? I bought a set years ago and used a pirated 600 cfm fan out of a kitchen exhaust hood. You can cludge them out of furnace filters and just a regular fan. (though there is some debate about how well they work.)

https://woodgears.ca/dust/air_cleaner.html

As for the condenser unit. They work better if the sun isn't blasting them. I'd put priority on making sure it's not a noise nuisance for you or the neighbor, then convenience for installation, then sun shade.

The interior unit can go wherever you want. Preferably in a place that is convenient and more or less blows into the center of the room. Installing a ceiling fan will go a long way to help move air around - and give you another ~5* of comfort.

 

[TheRealMcCory1]

Thanks for the info and the link, sands. I'll check the fan out.

 

[Jackfre]

Wiring on my Fujitsu and all fujitsu's from the condensing unit to the evap is 14-3/220. I would suggest that as well as a central dust collector that you look into an ambient air filter box. i use the JDS 200 and it has been very helpful. Primary dust collection, in my opinion, with a mshp is not enough. When you look at the coil spacing on these things you will see what I mean. Pseudo properly describes the supplied filters. Every system has a personality and you should closely monitor the evaporator. If the evaporator cover has an open grill type cover at the top, which I believe most do, try to position the evaporators height so you can get your head above it to clean and vacuum the top coil. In my kitchen I am looking at mine and it is about 3-4" from the ceiling. It works well, but it will be a pita when I get to pulling the cover to do a thorough coil clean. I think in a wood shop application, until you figure how it is going to go, you will be looking it over every time you make a dust storm

 

[TheRealMcCory1]

Haha, thanks Jack. I'll be sure to consider clearance when selecting the unit and especially when deciding on where to place it.

I've done some research on the air cleaner (I've noticed the one you mention, as a matter of fact). A neighbor has one and he is a believer as well. It's on my "keep in mind" list but is certainly not top priority just yet.

 

[JakeKohl]

Pull a neutral. If memory recalls, the evaporator (indoor unit) is 120

Not all brands wire the indoor unit the same. Some are powered from the outdoor unit. Some need their own discrete power source with communication wiring to the outdoor unit. Some use typical Romex betweeen indoor and outdoor unit, some use a 5 conductor wire.

In short, pick your unit before you wire for it. 30Amp is probably overkill but should suffice. My 18kBTU mini-splits each run off a 20amp 240V circuit.

You can usually download an installation manual off the net and plan ahead once you've decided on a model.

 

[46MGTC]

Not sure what is required at your location but I was told that I needed a 120v outlet within some short distance or within the exterior disconnect. I bought a disconnect box that had a duplex GFCI outlet along with the 240v connections. I guess this is a requirement for the tech to have a place to plug in his vacuum pump, etc. I managed to tee off an interior 120v run on the back wall of the garage.
Maybe that is just in North Carolina?

 

[mobiledynamics]

You could have tapped off one of the hot legs on the 220 for the unit.

But yes, I would figure out what cables are required on the prerun. Running the cables from compr/condesnser was a after thought for the OP. I was just thinking about the core main cables

 

[rugbyhick]

Are you sure you need 100A out there? I would think 60A would be lots! Easiest way to get it there is with 6/3 teck cable. It's direct burial. Run it through a 2" LB and a short piece of pipe to get it below surface. 10/2 wire to outdoor unit on heat pump, as far as between outdoor and indoor unit, it can be run with the pipes.

 

[TheRealMcCory1]

Thanks for the tips and advice everyone. I haven't been able to read these for the last day or so. Been traveling for work. So I think I have a much better grasp on what I'm facing here. Discussing with both the general contractor's electrician and my own electrician on how to approach this. I think maybe the most prudent option is to just run conduit with a pull wire. I can get my own electrician to install the correct wiring once I select the minisplit. (it's my cousin, so it'll just be the cost of materials). Jake, I'm just not prepared to make my minisplit selection yet. Haven't done enough research and not willing to spend that kind of $ on some I'm not 100% confident on.

Rugby, I really have no reason not to run 100a. I know it's crazy overkill but I'm getting the electrical for the garage done for free by the contractor as consideration for a mistake they made with the garage door.

Thanks as always,
Cory

 

[46MGTC]

You could have tapped off one of the hot legs on the 220 for the unit.

Are you sure about that? I was told specifically that I couldn't run a neutral line and tap off one of the 240 legs. In fact I remember also asking here and got told the same thing.

 

[rugbyhick]

You don't need a neutral for the mini split. I am an Electrician, never seen one that needs one. 12/2 will be enough. If you're not paying for the wore, then do the 100a I guess, just easier to work with 60a, and it would be lots

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[rugbyhick]

And if you're doing 100a, look I to 2/3 null text, bet it's cheaper than piping it

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[rugbyhick]

Run a 14/3 with that wire to use for a 3 way swith to turn the outside lights on and off from inside the house. Nothing more frustrating than getting back to the house and realizing the lights are still on

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[46MGTC]

You don't need a neutral for the mini split. I am an Electrician, never seen one that needs one. 12/2 will be enough. If you're not paying for the wore, then do the 100a I guess, just easier to work with 60a, and it would be lots /QUOTE]

I was refering to running a neutral for the 120 volt outlet that I was told was required to be near the outside 240 volt disconnect. I ran a separate12/2 for the 240 volt disconnect for the minisplit and a separate 14/2 120 volt service outlet for the "code" requirement.

I was questioning whether it was permitted to use one of the 120 legs of the 240 pair to get the 120 volt service outlet. If that was allowed would I not need a neutral?

 

[rugbyhick]

You'd be using the ground and one leg. Using the ground as a neutral is not allowed in Canada that's for sure!

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[Mustang51js]

Normally the split systems that I've done are 20 amp 220volt for condenser and then run a 12/3 romex or 12/4 rubber cord to where you want the fan from the condenser

 

[mobiledynamics]

I have had multiple mini splits in my various homes - Mitshi and Daikon.
In my current home, I have 4 condensers. He ran 50 amp 6awg with a neutral pulled to the primary pull box - before splitting off to the various disconnects.

I can't recall what gauge wiring was use for the evaporators. Maybe a mix of 14 and 18 ???- Just guessing as it was just a bunch of thhn in colors I never saw (he ran thhn down one main feed and branched it off. So each run had all different colors...purple, pink, you name it.