[roperman]

I'm thinking about putting a mini split unit in my upstairs office, a one zone, 12,000 BTU unit. I was wondering what you all would think about putting the condenser under the stairs, as shown in the picture, sorry about all the junk. The area under the landing is about 4 feet by 4 feet, and about 5 feet tall. The other option would be to make a slab on the little granite outcrop. My wife isn't keen on the idea and I want to make it as inconspicuous as possible. The house was built in 1932 and she doesn't think a mini split "goes" with a house that age.

Pros: it would be out of the sun and snow. Cons: it would be in a partially enclosed space. The lattice may let out enough of the heat, what do you think? Thanks!

 

[surferdude2]

That should be acceptable from a heat rejection standpoint... plenty of effective open area for convection currents to work ... and a 1 ton unit is small enough to do fine in there.

It'll be fun getting the lineset to that area. I don't envy you that.

You'll need a door or easily removable panel on there to comply with the access requirement per code.

 

[roperman]

The lineset will be installed right next to the downspout, kinda hard to see because the downspout is painted the same color as the shingles - it's to the right of the landing. I think prepping the area under the landing will be the worst, it's just dirt now. I'm planning on putting 4 inches of sand and a pad for the unit to sit on under there. I was thinking this would be the worst part of the install!

Happy to hear it might work in there, thanks for the advice.

 

[surferdude2]

Plenty of plastic prefab pads available. Good luck... sounds like you have a good plan. Not to worry, there's plenty of breathing room in there for the unit.

Prefab pads

 

[sktn77a]

If you're going to install it under those stairs, just replace one of the lattices with a functioning door/gate for service access.

 

[roperman]

Thank you both for your input.

My office is upstairs and is about 110 square feet, so fairly smallish. There are two other bedrooms closeby that I thought might also be cooled by this unit if I keep my door open. They won't be getting the best cooling because of the location, but better than nothing at all. The other rooms are 144 sq feet and 260 sq feet. They aren't always occupied, so not super important to have all this space cooled, all summer long.

For this reason, I was thinking about a 12,000 BTU unit. Way more than my office needs, but might be handy for the other rooms when needed.

The problem I've been reading about is compressor undercycling when you have too big of a unit outside for the space you are cooling on the inside. The compressor will kick on for a bit and then go off because the room was so easy to cool, and then cycle on and off. Bad for the compressor to run like that, from what I've read.

So I'm thinking of going with a 9000 BTU unit instead. It will stay on longer, and if the door is open, it will stay on a bunch at a time trying to cool the other rooms.

Maybe this isn't something I need to worry about.

Appreciate any advice, thanks.

 

[beenthere]

Doubt it will work well under the stairs enclosed like that. Your going to get some of the hot condenser air recirculating in there, which will lower the A/C's capacity, and make the compressor work harder.

How much electrical equipment is in your office.

 

[bfrabel]

Yes, smaller is usually better when it comes to air conditioning. Some of the fancier mini-splits have variable speed compressors that can adjust themselves to the size of the load better. If you were getting one of these types, a slightly larger than needed unit wouldn't be as big of a deal. Otherwise, I would agree that the 9000 BTU unit would probably be the better choice.

I don't like seeing condensing units in an enclosed area like that, but Surferdude is probably right that it might be good enough. I wouldn't guarantee it though. If there were large gaps in the stairs and/or deck boards above for the hot air to rise out of I would feel a little better about it. Even if the lattice were removed, I'm sure it would be against the install instructions to put it in a place like that.

If you do put it there, I highly recommend making it easy to get to so that you can get to it with a garden hose to rinse it out every once in a while.

 

[roperman]

That lattice looks horrible and is due to be fixed also. I like the idea of starting the lattice down about a foot from the top, so the hot air can get out easier.

I'll have to have access for code, so one of the lattice panels will be able to be removed easily.

The unit I'm thinking about getting does have the variable speed compressor so maybe I will get the 12,000 BTU unit. The price isn't too much different.

Thinking about splurging and getting a Friedrich that has an easily serviced and cleaned indoor wall unit. (Their video looked good anyway.) Looking at Daikin, Pioneer, Senville, and some others that are on Amazon. Mitsubishi seems way too pricey.

Thanks for your input.