Carrier AC 12,000 or 18,000 BTU Unit?

[stasera]

Hi this is my first post.

I'm in the process of putting in a Carrier mini-split ac in my home. I've been told from some contractors that a 12,000 btu ac would be perfect while others said I needed a 18,000 btu. My home is 31 x 40 square ft with 5 1/2 rooms. I always thought the bigger the better until the contractor told me that the 12k would be better because it would run constantly rather than an 18,000 which would run and stop.

I'm confused; which is more ideal for my home? I'd also appreciate any feedback re Carrier mini-split systems.

Thanks

[beenthere]

Never used a Carrier mini split.
I would have used an Inverter type.

You can guess at the size you need all you want. If you put in the wrong size. Well, youo can always buy another unit.

If a contract sells and installs the wrong size. Replacement is on his dime, not yours.

[CincyHVAC]

I would go with the 18K. But why the mini-split? Is there no way to duct in a standard split system?

[udarrell]

There should be a manual J load calc done, so the contractors know what they is doing.

A one ton might handle the heatload, who knows.

Well, with a mini-split, you don't have to worry about duct system losses & duct costs.

I would look at the CFM airflow the indoor coil unit delivers, I would lean toward the one with the highest CFM per/ton of cooling.