DIY Home Improvement Forum banner

Mini split sizing for variable size room

1601 Views 7 Replies 5 Participants Last post by  user_12345a
I was considering getting a Pioneer Ductless Wall Mount Mini Split INVERTER Air Conditioner with Heat Pump, 18000 BTU (1 Ton), 15 SEER, 208~230 VAC for cooling a room. The room is about 14x14x10. This room is connected to another slightly smaller room which needs cooling only when we have guests.

Ideally I need the one unit to cool the one room all the time and both rooms sometimes. I am told that the inverter function will allow the unit to scale itself to keep the proper temperature regardless of which size room it is being used in.

I am trying to decide between the 18000 and the 12000 btu unit. I currently have a portable unit by delonghi that is the biggest piece of garbage ever to come out of china, it leaks everywhere despite being "drain-free" and it has no input tube so it just sucks hot humid air in through all the cracks due to negative pressure... Anyway... that thing is around 12000 btu I believe, and it is able to cool the one room very well, in fact it cycles frequently, leading me to believe that it could be smaller and still do the job just fine. Honestly I think I could get away with a 5k window unit for the one room.

The mitsubishi sizing info page says that 12000btu should be sufficient for up to 500 sq ft, whereas my rooms would only be ~200 or ~400 sq ft

I don't mind paying the extra few hundred for the 18k mini split, but only if the inverter will allow it to scale properly down to cool the one room when I only need the one room cooled.

See less See more
1 - 2 of 8 Posts
1 ton could be sufficient for up to 1000+ sq ft depending on the cooling load.

the sizing charts are useless - you can end up with 2 to 3 times as much cooling as u need using them.

Any mini-split will be oversized for a single 200 sq ft +/- room unless you have an exceptionally high cooling load (many people meeting in a room, kitchen appliances, all glass wall etc) load.

If you can get a 9000 btu do so, do not even think about 18k. Even if it can run at 40% capacity, the 18 will still be far too big.

Once you get above 12k you're looking at enough cooling capacity for a small house rather than room. Lots of smaller houses can cool with 1.5 to 2 tons.

With minis you actually need less capacity compared to central - there's no duct loss, the cooling is delivered where it's needed. Highly efficient.
See less See more
They are pretty much the exact same price; given that- should I go with the 110V 9000btu or the 220V 12000btu? I have been told that 220V is better due to lower current therefore more energy efficient (despite being the same wattage). If they can scale so well would there be any reason to not get the 12000?
Check the product specs - see what the minimum capacity is.

The smaller unit gives a lower minimum which is good. You're wasting your money by getting a 12000 if it can only drop down to 4 to 5000 btu, it will cycle on and off just like a window unit would.
1 - 2 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.