Yes, another mini split question...

[Klakeman]

I am finishing out a 37x40x10 garage for cars and motorcycles. Walls are insulated and finished with a layer of plywood and final layer of Sheetrock. The floor will be epoxy. Ceiling is painted plywood with insulation in attic. I will probably have one large ceiling fan in the center of the garage too.

I live in N Ga and simply want to be able to work in the garage in the winter and summer without freezing or sweating to death.

My contractor and other vendors are happier with traditional 3-3.5 ton ducted heat pump systems. This seems to be because they are not experienced with ductless systems and don't think the ductless units will handle my square footage.

However, a local hvac contractor has offered a bid for a 30k BTU mitsubishi mini split with a single interior unit. Based on what I have seen on this forum, this unit should do fine. I like the small exterior footprint, the lack of ductwork, the efficiency, etc. The installed cost is competitive too.

I plan to visit a local facility with a Mitsubishi mini split soon to see one in action.

Am I on the right track or should I cave in to the more traditional ducted advocates?

Thanks!!

Kirk

 

[theoldwizard1]

1600 sq ft will be awful hard to heat/cool from one outlet ! How many outlet were the traditional guys quoting ? Mitsubishi seems to be the leader in this market. You can get multiple outlet with just one exterior unit although this would drive up the cost.

Ceiling fans would help a lot buy that is another thing to worry about for tall items stored inside.

 

[pseudorealityx]

Mitsubishi has ducted units. If you like all the other parts of that type of system, look in that direction.

 

[RKA]

I would want at least 2 units inside for a space that large (in spite of the fan being there). Once you're up to a 30K mitsu I don't think the incremental cost for a multi head unit is that much more (I'm far from an expert on their pricing though), so it's worth asking.

If you intend to maintain temps in the space the 30K should suffice. If you intend to shut it off and only operate on occassion, I suspect you'll need more capacity on the heat side otherwise it will take forever to bring the space up to temp. An option is to leave a 220v 30A line open for supplemental resistance heating. Then wait and see how the minisplit does, and if you need it, add it.

 

[Jackfre]

As you have no Manual J Heat Gain/Loss for the building this is all conjecture. A 30 may do the job. Maybe not. One good thing about mshp's is they are the ultimate in zone control. I'd put the 30 or a 36 in and define the load by experience. If you need more, you add more.

I will say that you could go to a single 36 or a Dual 36 with 2 18 evaporators. I think you would be happier with the dual set-up. Two evaps will provide better air circulation. On my place I did a 24 dual with two 12's and found it to be pretty economical. I compared the 36 with 3 evaps and found I could buy the dual and a single 50% more efficient single unit for the same cost as the triple. Based upon my lay-out and use (upstairs & down) I put the single downstairs and the dual in the bedrooms. Explore all of your options and combinations thoroughly.

The key to success on mshp's for a shop is to have good instruction on routine cleaning of the evaporator and stay up with it. If you do a really dirty job, check out the coil face.

I'm partial to Fujitsu, having represented them in my business. My experience is that Mitsu is competitive in the lower sizes, 7, 9 & 12, but as you start up the scale they start making up margin quickly. I could always beat the pants off them in the bigger sizes. That still holds true. Mitsu is excellent equipment, but they have nothing over Fujitsu other than higher price