Mini split sizing challenge

[nonhog]

Any experts care to give an opinion on sizing my garage (eh hem! home atrium) space.
its only a 15X15 room 225 sq. ft. but... it has a glass ceiling/roof and one wall over 17' (a few inches over) and another about 15' tall.
It get blistering hot in the summer so we cover it with a shade sail as soon as it gets hot out. Late June-early Sept. and cold in the Winter.

It doesn't have to be perfect just much better. Hate to overdo it, maybe the unit won't allow that?

Help!

 

[dcg9381]

I'm not in your geography, so I'm not going to guess on sizing.
I will say that these inverter mini-splits are not subject to the conventional ducted AC problem of over-cooling and lack of de-humidification. Basically, get close and they can throttle down.

My guess is that it's the UV that's killing you guys in that room.. Any way to tint or otherwise UV protect those panels?

 

[nonhog]

I just tried an online calculator and it showed 10,900 BTU. I'm sure its close but probably not perfect.
12K is closest to that from the style I'm looking at.

dcg9381, its only really bad in the Summer and like I posted we do put up a shade sail every year, cools the whole house down but still too hot in the atrium.
https://www.homedepot.com/p/Shelter...6gOBbl4Pg594H4u2zkxoCWY0QAvD_BwE&gclsrc=aw.ds

 

[nonhog]

I'm not in your geography, so I'm not going to guess on sizing.
I will say that these inverter mini-splits are not subject to the conventional ducted AC problem of over-cooling and lack of de-humidification. Basically, get close and they can throttle down.

My guess is that it's the UV that's killing you guys in that room.. Any way to tint or otherwise UV protect those panels?

Oh I failed to mention we are surrounded by Fir trees and my wife wants all the natural light we can get. Always a challenge

Thanks for the reply

 

[justinjoyal]

I'm not in your geography, so I'm not going to guess on sizing.
I will say that these inverter mini-splits are not subject to the conventional ducted AC problem of over-cooling and lack of de-humidification. Basically, get close and they can throttle down.

My guess is that it's the UV that's killing you guys in that room.. Any way to tint or otherwise UV protect those panels?

False.

They allow a certain "error margin", but a grossly oversized mini-split will cause the same problems as an oversized conventional system.

 

[justinjoyal]

OP: Proper sizing is achieved through a proper load calculation. Anything else is guessing.

For that, we need your location, the building's orientation, insulation R-values, etc.

But. If I had to guess, I'd say 9k if humidity is usually high and heating capacity is not a huge concern.

 

[dcg9381]

They allow a certain "error margin", but a grossly oversized mini-split will cause the same problems as an oversized conventional system.

I agree with you here, but also stand by my comments... Ductless units are not as sensitive. Grossly oversized, I'd agree, but there more margin of error with units that can throttle down.