Ductless A/C unit

[Shamoan]

I have about a 300 sq ft bonus room that i'm finishing up and will likely go with a ductless Mitsubishi ac unit or something similar. any experience with these type of units with pros and cons? I would really like something with enough punch to keep it cool, as many bonus rooms struggle with cooling loss and i dont want it to be an issue and have done the prep work to insulate as well as possible. the upstairs has a bath and bedroom with attached stairway. im guessing the bathroom will require a separate unit.

 

[Jeffreauxdawg]

You can get a single pump 36,000 btu or so with 3-4 heads for less than $3k.

ETA. My wife would never go for the traditional head.... She thinks it's ugly. So you can opt for the ceiling cassette type that fits in the rafters, but I would assume that a bonus room on the second floor won't have room. In that case, check out the LG cool art mini split. The head looks like a picture frame.

 

[msudawg12]

Moved into a house a year ago with "bonus/bedroom/bathroom" setup similar to what you're talking about but slightly larger.

Main room is 13x22 with two shoot offs to dormer windows
attached via barn doors is 11x16
attached to bathroom with shower
attached 2 walk in closets

The unit in the upstairs is a Mitsubishi model MSZ-GE15NA and it works tremendously. Doesnt have to run all the time. Always comfortable.

Previous owner had a son that used it for his bedroom.

 

[My Bru]

I have that set up too, and it has its on unit. The biggest thing I'd say is that if the room is up next to the roof, then it'll never really be cool unless you install attic baffles to allow the air flow from soffits up through the ridge vents (if you have them). My unit is about 25 years old and will go out any day now. I'm considering the mini-split myself when that time comes. Without the AC it gets to like 105 up there during the summer.

Why would your bathroom need a separate unit? Is it not insulated?

 

[HotMop]

36,000 btu for a 300 sq ft room? You could hang meat with that much cooling. Roughly go with 20 btu per sq ft.

 

[garddog]

A mini split for 300 sq ft is overkill. Even an upstairs room can be kept cool with a 12k btu window unit. That is less than $400.00 for the nicest one out there.

 

[Bulldog from Birth]

Just remember that the normal btu/sq ft rules don’t apply for bonus rooms above a garage. You’ve got a whole big section of heat transfer area (The floor) that you don’t have in the interior of a house.

 

[Shamoan]

bathroom is near stairs. im worried about air getting sucked down the stairwell and not cooling well enough in the bathroom. stairwell door, steps, landing, 90* turn, steps, landing with bathroom to the right, kind of a landing entry area, with closet, then main room.

 

[Shamoan]

window units not allowed in neighborhood covenants.

 

[garddog]

window units not allowed in neighborhood covenants.

That sucks. They do make portable ones that run around $600 to $700.

Do you not have any ducting up in that area? You could do a small outside unit and tie it in to the existing ducts if they are already there.

 

[My Bru]

Just remember that the normal btu/sq ft rules don’t apply for bonus rooms above a garage. You’ve got a whole big section of heat transfer area (The floor) that you don’t have in the interior of a house.

Yep. Near impossible to keep it cool, especially if your roof isn't shaded, good insulation or not.

 

[Shamoan]

No ducting. I just want it to be as cool as the downstairs will be. Im not against spending a bit extra to make sure it stays cool, as it will be used as a bedroom since it has its own closet and br.

 

[DesotoCountyDawg]

Those ductless units are throw away units. The parts and service are so expensive you’ll be replacing the whole thing.

 

[The Peeper]

We have a spare bedroom on the farthest end of the house away from our a/c. If its really hot outside and someone is staying in there it tends to be the warmest room in the house. 3 or 4 years ago for $400 we bought a portable unit at Lowes that just stands in the corner of the room and ducts outside through a small fitting in the window. It has a condensation pan but we've never had to dump it, ever. It will run you out of that room in no time too. They also make ones that you don't have to duct outside but there was a window right there so we just did it that way. It looks something like this.

 

[HotMop]

An 8k btu is $800-$1000, so yeah, disposable.

 

[Jeffreauxdawg]

36,000 btu for a 300 sq ft room? You could hang meat with that much cooling. Roughly go with 20 btu per sq ft.

Good point. I was referring to one I bought a few years ago for about 900 sf of living/kitchen areas and a couple of bedrooms upstairs in a flip. We went with 35-40 btu per sf. But that was about heating the space I think.

 

[msudawg12]

bathroom is near stairs. im worried about air getting sucked down the stairwell and not cooling well enough in the bathroom. stairwell door, steps, landing, 90* turn, steps, landing with bathroom to the right, kind of a landing entry area, with closet, then main room.

Nearly same setup except for the landing and turn. No issues in bathroom