Mini-Split Indor Unit Types and Location

[rnpatrick]

Hey All,

I am getting to the point I need to think about A/C for my garage. It is pretty simple, 30' deep, 60' wide, 4-bay with 13.5' high ceiling.
All 1 big room - at this point everything still open, no insulation or drywall yet.
The roof is a steep pitch and I have a ton of space to install equipment in the attic to run lines, install ducts and air handlers, etc.
The A/C calculation I had done calls for 26,000 BTU cooling load.
The attic will be unvented and insulated so putting A/C equipment up there is not an issue.
In the near future I plan on finishing some space in the attic that will also need A/C
I'd like to go with a mini-split system that will give me a single outside unit that I can use for both the garage and attic.

I can get a single mini-split wall unit that give me that cooling capacity but it is going to be terrible for air circulation in a room that big.
So one option would be to use multiple smaller wall units spread around the room but I am still not sure that circulate in a room this size.

I also see the mini-split manufacturers now also make concealed duct units - essentially like small air handlers that can be attached to ducts.
I have considered using those and running ducts to get the air distributed around the garage.

People that have done this before - would you use multiple wall mount evaporators or use concealed duct units?

Cost and labor are less factors than comfort since I will be doing the work myself.

Thanks for you advice!
RP

 

[Yankeefarmer]

If you are willing to run ducts, forget mini splits and go with a conventional split system. Are you going to be doing activities in there that will create dust that can foul filters?

 

[ace10]

Are you sure about that 26K BTU load calc?

I've got about 2/3rds your interior volume, excluding your attic space, insulated with R23 walls, R40 ceiling and R17 garage doors. HIgh end Marvin doors and windows.
Two trusted HVAC vendors spec'd and quoted the job. One was 2 units @36K and the other was triples @45K.
I went with dual 18K Mitsus, with a 7 foot fan in the high bay for air movement.

My equipment has no problem with the climate and site, which is exposed and very cold and windy the winter.

 

[fitter30]

Ducted unit would be better than wall units. Wall units have to be cleaned more often because their is poor filtration. Duct units can use a pleated filter.

 

[yeldogt]

Are you sure about that 26K BTU load calc?

I've got about 2/3rds your interior volume, excluding your attic space, insulated with R23 walls, R40 ceiling and R17 garage doors. HIgh end Marvin doors and windows.
Two trusted HVAC vendors spec'd and quoted the job. One was 2 units @36K and the other was triples @45K.
I went with dual 18K Mitsus, with a 7 foot fan in the high bay for air movement.

My equipment has no problem with the climate and site, which is exposed and very cold and windy the winter.

Confusing what the total is --- do you have a total 36 or two heads on a 18k

 

[yeldogt]

Hey All,

I am getting to the point I need to think about A/C for my garage. It is pretty simple, 30' deep, 60' wide, 4-bay with 13.5' high ceiling.
All 1 big room - at this point everything still open, no insulation or drywall yet.
The roof is a steep pitch and I have a ton of space to install equipment in the attic to run lines, install ducts and air handlers, etc.
The A/C calculation I had done calls for 26,000 BTU cooling load.
The attic will be unvented and insulated so putting A/C equipment up there is not an issue.
In the near future I plan on finishing some space in the attic that will also need A/C
I'd like to go with a mini-split system that will give me a single outside unit that I can use for both the garage and attic.

I can get a single mini-split wall unit that give me that cooling capacity but it is going to be terrible for air circulation in a room that big.
So one option would be to use multiple smaller wall units spread around the room but I am still not sure that circulate in a room this size.

I also see the mini-split manufacturers now also make concealed duct units - essentially like small air handlers that can be attached to ducts.
I have considered using those and running ducts to get the air distributed around the garage.

People that have done this before - would you use multiple wall mount evaporators or use concealed duct units?

Cost and labor are less factors than comfort since I will be doing the work myself.

Thanks for you advice!
RP

AC is as much about getting the water out of the air as cooling it ...... placing a single Minisplit towards the work area is fine is a big space. I have used single sorce Ac w/o issue in a 1600 -- 1700 sf space. Heat can be a bit different depending on how tight the building -- leaks make for uncomfortable space in the winter.

Much will depend on the doors -- w/o quality doors property installed to minimize leaking your load will be higher and if you are working near the doors the head will need to be closer.

Most people set up shop to work on the other side of the garage from the doors -- with the mini on that side it works well.

Anything can be done .... you could do a VS split system w/ zoning. IMO -- even in a detached garage having the two spaces is better and if you go mini -- do two. Multi work best when all the heads are on -- you don't want one space on all the time with the upstairs head off. Same if you went with a duel in the garage -- both of the heads should be on. Multi units always cycle some refrigerant to all the heads regardless of if they are on or not. If one head in the mix is typically off .... best to go separate

 

[ace10]

Confusing what the total is --- do you have a total 36 or two heads on a 18k

2 18K systems. One head per. 36K total.

It's an L shaped garage. The two heads point in different directions.

1650ft2, just under 12' height, with one bay up to 17'.

 

[yeldogt]

2 18K systems. One head per. 36K total.

It's an L shaped garage. The two heads point in different directions.

1650ft2, just under 12' height, with one bay up to 17'.

Have you ever tried to only use one unit ? I have 1600sf in PA and 15k will do the whole thing

 

[PoorUB]

My seat of the pants load calc says 36K BTU.

I cool a 900+ sqft shop here in ND on 18K BTU. I had a 12K window shaker that would maintain if I let it run, but if I started it in the middle of the day it would not catch up so that tells me the cooling load is fairly accurate.

 

[ace10]

Have you ever tried to only use one unit ? I have 1600sf in PA and 15k will do the whole thing

Only when I had a rodent problem in one of the heads.

With a single head, I'd need to keep the floor fan going, just to move the air around. The space is filled with cars sleeping on four posts lifts. Not much flow from one head, and the big ceiling fan doesn't hit all the corners.

I consumed about 5100 kwh in the past 12 months. All uses, including the machine shed which is a separate building where that service comes in. I'm sure I could fiddle with the programming on the Mitsu units to be a little more efficient, but I'm finding them quite efficient as is.

 

[aqr81]

I put (2) 2 ton Daikin mini splits in the shop I am just completing at my son's house. 33' X 44' they are very efficient and we couldn't be more pleased with their performance. Daikin is a leader in Europe for these and has been making them for years and now getting market share here. Put the inside heads in middle of shop facing each other, ran line sets through attic space and out & down back wall to the mounted units, drains out side wall into weeping well. They are very quiet running units and require little maintenance, just hose off the coils once in a while. I'm in the Central Valley Ca so heat is our issue more than cold.

 

[rnpatrick]

AC is as much about getting the water out of the air as cooling it ...... placing a single Minisplit towards the work area is fine is a big space. I have used single sorce Ac w/o issue in a 1600 -- 1700 sf space. Heat can be a bit different depending on how tight the building -- leaks make for uncomfortable space in the winter.

Much will depend on the doors -- w/o quality doors property installed to minimize leaking your load will be higher and if you are working near the doors the head will need to be closer.

Most people set up shop to work on the other side of the garage from the doors -- with the mini on that side it works well.

Anything can be done .... you could do a VS split system w/ zoning. IMO -- even in a detached garage having the two spaces is better and if you go mini -- do two. Multi work best when all the heads are on -- you don't want one space on all the time with the upstairs head off. Same if you went with a duel in the garage -- both of the heads should be on. Multi units always cycle some refrigerant to all the heads regardless of if they are on or not. If one head in the mix is typically off .... best to go separate

Yeldogt - you raise some interesting points. This garage will have the main garage level which is completely open and I would anticipate needing to be treated as 1 zone even if I end up with multiple evaporators for airflow purposes.

But the attic, when finished, would be completely separate. I can imagine that 90% of the time only one area will be cooled or heated.

So now I am thinking to put one unit on the main level, sized just for that level. Then add a second system when/if I finish the attic. I had wanted only one system so I would only have 1 outside unit but that is a minor consideration in light of how inefficient that will be compared to 2 systems.

And I am leaning toward using the ducted inside units even if I end up just hanging them from the ceiling inside the garage and having a minimal amount of duct to distribute the air. The ceiling is 13' above the floor and at least this way I can put a nice size filter on the unit so I don't have to climb up there and clean it as often.

Thanks for the info.
RP

 

[PoorUB]

Personally I would not bother with ducted units. The do not blow very hard and probably would do worse that one wall mounted head. They certainly will not blow the air down to the floor. Just install one or two ceiling fans.

An other option would be a Gree Flex. It uses a mini spit outdoor unit and a more normal air handler. The Gree Flex will push some air. You can also get it up to 5 tons in a sinle unit.

Gree Flex

You could mount a Gree Flex air handler in the attic, run duct in the attic space on the floor the length of th building and have a few registers and a couple returns. Totally hide the system.

Mr Cool sells the same unit under their label.

 

[justinjoyal]

Personally I would not bother with ducted units. The do not blow very hard and probably would do worse that one wall mounted head. They certainly will not blow the air down to the floor. Just install one or two ceiling fans.

An other option would be a Gree Flex. It uses a mini spit outdoor unit and a more normal air handler. The Gree Flex will push some air. You can also get it up to 5 tons in a sinle unit.

Gree Flex

You could mount a Gree Flex air handler in the attic, run duct in the attic space on the floor the length of th building and have a few registers and a couple returns. Totally hide the system.

Mr Cool sells the same unit under their label.

x2

I dont bother with ducted units..

When it comes to central air, Gree’s system is pretty much all I install now, it performs really good.

I wish the air handler was modulating though…

 

[hale1730]

Hey All,

I am getting to the point I need to think about A/C for my garage. It is pretty simple, 30' deep, 60' wide, 4-bay with 13.5' high ceiling.
All 1 big room - at this point everything still open, no insulation or drywall yet.
The roof is a steep pitch and I have a ton of space to install equipment in the attic to run lines, install ducts and air handlers, etc.
The A/C calculation I had done calls for 26,000 BTU cooling load.
The attic will be unvented and insulated so putting A/C equipment up there is not an issue.
In the near future I plan on finishing some space in the attic that will also need A/C
I'd like to go with a mini-split system that will give me a single outside unit that I can use for both the garage and attic.

I can get a single mini-split wall unit that give me that cooling capacity but it is going to be terrible for air circulation in a room that big.
So one option would be to use multiple smaller wall units spread around the room but I am still not sure that circulate in a room this size.

I also see the mini-split manufacturers now also make concealed duct units - essentially like small air handlers that can be attached to ducts.
I have considered using those and running ducts to get the air distributed around the garage.

People that have done this before - would you use multiple wall mount evaporators or use concealed duct units?

Cost and labor are less factors than comfort since I will be doing the work myself.

Thanks for you advice!
RP

I would love to get Ac in my garage. I put heat in several years ago but these hot, humid summers are killing me in my old age.