Where to put the mini-split

[rok_hunter]

I tried the search function for a couple hours but haven't been able to nail down an answer to this question: I'm building a 30x40x12 enclosed pole barn, adding spray foam insulation, and will be installing a 3-ton MrCool mini-split unit. My plan was to put the unit on the back (north) wall, "option 1", on the attachment. Lately (i.e. over the last 2.5 hours) I've started wondering if putting it on a side (east) wall ("option 2") would be better.

I've read not to have the inside unit in direct sunlight because it can mess with the temperature settings. Option 1 would have sunlight coming in the windows and potentially reaching the inside unit, but would keep the external unit 100% shaded all day long. Option 2 keeps the sunlight off of the inside unit, but would let the sun hit the 'side' of the external unit for a couple hours each day; it wouldn't be in full sun in the morning because of surrounding trees. (Also because it's Florida, I'm considering having window coverings anyhow to reduce the heat inside.)

I'm also looking at airflow; I'll have a workbench on the bottom (south) wall with the windows and, theoretically, if I have the door(s) open the air will flow towards the doors. If it works that way option 2 seems to keep air moving through the whole shop, but option 1 doesn't.

Thoughts?

 

[rok_hunter]

Since the attachment didn't take:

 

[yeldogt]

I like option one -- how does the outlet work on that unit -- the better ones will move back and forth. You don't want the outside unit it the heat all day ... I have never noticed any temp control problems when the sun hits my inside unit.. the fans are running all the time.

With spray foam you should have fairly stable temps ....make sure to seal the doos well

 

[rok_hunter]

..... how does the outlet work on that unit -- the better ones will move back and forth.

This one moves back and forth as well, and supposedly "follows" you as you move. I don't know the range on that though, if I'm at the workbench it's going to be 27 feet behind me in option 1. I'll make sure to check the door seals! It'll help keep bugs under control inside as well, for sure.

 

[Rusty Fords]

sorry to say again nore than 26 years in the HVAC trade( I got to figure out how to enter a signature with this info).

If money is available I would go with 2 units each unit a little over 1/2 of the total capacity what you believe you are going to need and put them equally spaced on the wall where #1 option is. 30X40 is a large area for even temp control throughout the building and if one breaks then you have another running.

Fujitsu and Daikin units the temp sensor is in the indoor head (not sure about the others I haven't worked on them) and with the fan running all the time shouldn't have much of a problem with bad temp reading.

 

[rok_hunter]

...If money is available I would go with 2 units each unit a little over 1/2 of the total capacity what you believe you are going to need...

I actually came really close to this, with two 18k BTU units. That would have given me a little better SEER (20 for the 18k units vs 16 for the 36k) but took me another $1000 or so into the red, for the MRCOOL DIY versions anyhow. It certainly was the preferred way to go but I had to scale back and make decisions between that and my electrical plan. If I had been able to find a local HVAC tech who could have done the install for the "normal" (not DIY) models for a price I could afford it definitely would have been the preferred route.

 

[Jackfre]

I was a couple paragraphs into a response when I finally decided that in a climate control discussion knowing if you are in Minot or Miami is important to the discussion. So I said the hell with it. You must be a secret agent. "Home" is cute but doesn't help.

 

[rok_hunter]

I was a couple paragraphs into a response...

Thanks for taking the time to ....not reply? I guess? I did mention I'm in Florida so, while we do have a "St Petersburg" like that other absurdly cold climate, we don't have a Minot. Most climate zone maps also put most of Florida, except "just the tip", in Zone 2 -Miami included, although just barely. To narrow it down though I'm up in the panhandle area, the northwest part of the state (many refer to it as "Lower Alabama". The abundance of redneck hillbillies anywhere more than 2 miles from the coastline reinforces that.)

If you were working a couple of paragraphs then presumably your response was going to delve into insulation R values, BTU and cooling capacity, sun exposure, building reflectivity, window and door insulation, and things like that. All valuable inputs that I welcome for additional consideration on my next build, and maybe to tweak some things on this one, but for now my hardware is pretty much set: 29GA steel, light color (I had the reflectivity values when I picked the colors but forget them now), roll-up metal door (which presumably has minimal insulation value), steel walk-through door, contractor-grade windows (all doors & windows on the south wall), 2" of closed cell on the walls, and 3" of closed cell on the ceiling, on a 4" non-heated/cooled slab. The mini-split on order is a 34.5 BTU cooling/36K heating unit, 16 SEER.

Also, all the spears I threw up front are in jest. I appreciate you taking the time to help out.

 

[Jackfre]

I do beg your pardon. I looked and did not see a location. I was going to suggest the Fujistu 36RSLX. It is only 14 seer, but for air circ it has a high of 1089 cfm vs 690 for the 36 wall unit. I have had excellent results with these units in larger spaces. It is not a cassette. It is a ceiling suspended unit so it is much easier to service than the built-in cassettes. The other side of my Minot or Miami had to do with the location of the condensing unit. Normally, if heat was your primary concern, place the unit where the winter sun can fall on it. Conversely, for your FL install try to keep the unit out of the direct summer sunlight.
Had you simply said the "Redneck Rivera" as my friend from the panhandle calls it I would have gotten it right away.

 

[rok_hunter]

Excellent inputs. Thanks! Redneck Riviera is definitely a term around here but not many from outside the area know it [emoji1787]

Sent from my Pixel 2 XL using Tapatalk

 

[yeldogt]

With spray foam and tight doors -- I don't see any problem with one head in a big open space. Check out the throw .. my Mitsubishi can blast me 25' away.

The key with AC is running them enough to keep the humidity down. It's not just "heat" that AC must contend with when cooling a space. Removing water from air requires capacity.

Understand -- that most load tables don't factor spray foam ... so you end up with more capacity with those tables

 

[Jackfre]

Some models have a "dry mode". The purpose of dry mode is to run the fan at a low speed while just keeping the coil cool enough to condense and give dehu without overcooling.

 

[Justin311]

Some models have a "dry mode". The purpose of dry mode is to run the fan at a low speed while just keeping the coil cool enough to condense and give dehu without overcooling.

You're right about most of that....but technically its to dry your clothes in asia...but we americans try to use it for dehu. It kinda works if you setup a proper controls system lol

Sorry couldn't help myself, former mitsu ductless engineer here

 

[road_king]

Option 1
This is basically same location I installed it in my 30x40x14 garage

 

[SALIV8]

You're right about most of that....but technically its to dry your clothes in asia...but we americans try to use it for dehu. It kinda works if you setup a proper controls system lol

Sorry couldn't help myself, former mitsu ductless engineer here

People use mini splits to dry clothes in Asia? Had no idea.