Mini split considerations

[Elysian]

Hi all,

I have a 34×22 foot stick built barn on the property I just bought in SW Michigan. First floor is a garage and the second story is a finished space with a peak ceiling and ceiling fans. Barn has running water to it in the winter and has duct work for a natural gas furnace that has been removed. Insulation on the walls on the ground floor are R13 and I'm unsure what's underneath upstairs though I could check.

A mini split seems like the best option to be able to comfortably be able to use the space year round but I have a few questions...

1) What size system would you folks recommend? Our son will probably end up converting the upstairs into his hangout as he gets older.

2) Following up with that would you recommend a two zone system for winter? I know heat rises but will a single mount downstairs where the bathroom and everything g is located still keep it comfortable in the winter? I'm less concerned about cooling in the summer up there due to the fans.

3) Barn is currently powered from the main breaker in the house on a 40 amp 240 into a subpanel in the barn. Can I run system from the subpanel or will I need to go straight from the box? There isn't much in the barn to power aside from a electric water heater, tv, and lights, 110 plugs.

4) Finally, the unit would be facing the west with a large field blowing towards it. What should be done in regards to prep work?

 

[Notgrownup]

Proper load calculation would be a good idea... you can go to www.alpinehomeair.com and they have one i think. Comes pretty close anyway

 

[theoldwizard1]

How much insulation do you have under the roof deck ? Even in SE MI, 6" is minimal, 12" preferred.

Forget the "heat rises". You need 2 air handlers, one up, one down and probably some fans for proper distribution.

If you have running water, plan for a back up heat solution for when you have an extended power outage in winter (or know how to quickly drain the system).

Yes, you can run it off of the existing subpanel. Don't take up welding as a hobby or buy a 5HP air compressor. Either the heat pump or one of the others, probably not both !

 

[Elysian]

How much insulation do you have under the roof deck ? Even in SE MI, 6" is minimal, 12" preferred.

Forget the "heat rises". You need 2 air handlers, one up, one down and probably some fans for proper distribution.

If you have running water, plan for a back up heat solution for when you have an extended power outage in winter (or know how to quickly drain the system).

Yes, you can run it off of the existing subpanel. Don't take up welding as a hobby or buy a 5HP air compressor. Either the heat pump or one of the others, probably not both !

Roof in the upstairs is sloped so no deck upstairs. I'd have to pull a board off and see the depth but exterior walls are 2x4 and R13.

Basically a minisplit doesn't really make a lot of sense for the whole system. Been doing a lot of reading today and what seems to make the most sense is a split system... probably 24000 for the garage portion and just use ceiling fans for the kids upstairs.

Water shutoff out here is extremely easy but I think for the winter I'm looking at just putting another furnace in to the existing ductwork.

 

[theoldwizard1]

Basically a minisplit doesn't really make a lot of sense for the whole system. Been doing a lot of reading today and what seems to make the most sense is a split system... probably 24000 for the garage portion and just use ceiling fans for the kids upstairs.

Disagree.

Mini-splits usually cost less to install (not if you already have duct work installed) and cost less to run (much higher SEER). If you are not using one room, turn off that air handler.

 

[Elysian]

Disagree.

Mini-splits usually cost less to install (not if you already have duct work installed) and cost less to run (much higher SEER). If you are not using one room, turn off that air handler.

Issue is I already have ductwork just no furnace.

Based on what I'm seeing I'll need a ~40k system.

At least according to the website in the earlier response.

I guess I could just get two 24k systems but... would I have to worry about the system keeping the place above freezing?

 

[Yankeefarmer]

If you already have ductwork and a natural gas line to the building, installing a gas furnace might be your best bet to ensure wintertime heat. Then you just gotta figure out how badly you want to provide summertime AC for your son.

I’m assuming there’s a difference between a hangout for your son and his bedroom/living quarters.

 

[LS6 Tommy]

You say you have ductwork, but haven't had load calcs done for sizing the A/C. How do you know the ductwork is the correct size? First you said you think 24k, then you say 40k. Sounds like there's not much chance the tin is sized right.

Tommy

 

[Elysian]

Apologies for the confusion.

The upstairs of the barn is all finished with ceiling fans installed. There is also ductwork in place but the furnace is no longer there.

Downstairs is my shop, hiding from the wife space, bathroom, and where my gym is.

Based on calculations a split system for both zones upstairs/downstairs would require around 40k.

If I just wanted to cool the garage level that would require a 24k unit.

I'm leaning towards installing a furnace for the winter and a split for the just the lower level.

I'm unsure I'd trust the split to keep everything from freezing for that 1 week solid we always get of single digits.