This is an additional question to my earlier question: Do those of you who have a mini split system find that the air circulates well? I haveconnected dining and living rooms -- connected by a space that is the equivalent of wide french doors (without the doors). Two contractors have told me that installing one mini split unit will be sufficient and the air should circulate properly. However, a third says no. Thanks in advance!

Listen two both types of systems before purchasing.
Unico systems produce more noise than a well designed conventional system, but it is a simple wooshing sound from the air flow.
Mini-splits are typically louder since the returnand fan aer in the room.
Mini-splits also suffer from the same problems as window type units for air circulation. They have to rely on moving the air away from the unit with enough speed to prevent it from simply being recirculated in the unit again. High air speed equals noise from the fan and the moving aid.

I am thinking of the same thing for my house. Do I want mini-splits, or whole-house air.

What I can tell you about circulation is that yes, it will circulate with a little help from a fan. In my previous old house, I had an 18,000 btu window AC in my dining room, and I had a small pedestal fan in the dining room, which was pointed towards the living room. With that fan gently blowing the air into the next room, the one window unit easily cooled down my entire downstairs.

Now, I have a large living room, and a large Kitchen, separated by a dining room. If I put a mini split unit in the living room, and one in the kitchen, the dining room will cool off just fine, especially if there's a little fan pushing some of the cool air into the room.

I actually find mini-splits to be much quieter than conventional ducts. The kind I have now, Daikin produces only 26 decibels on low. If I were you, I'd put one unit in the dining room and one in the living room.

"...produces only 26 decibels on low."

And how often do you use it on low?

We have a Unico/Spacepak system. We were told that oversized systems traditionally have the noise problems - but ours is incredibly quiet.

We considered the slim systems and I cannot even tell you how happy we are that we spent the extra money to get the unico system installed.

We had a lot of contractors our and considered a lot of different options and we chose 2 separate systems one for the first floor and basement and one for the second floor. We have an air handler in the basement and the attic.

I'm really noise sensitive - like when someone has the radio turned all the way down it drives me nutso, I think the key is having a properly designed system.

**Also it was my understanding that installers push the slim systems because the profit margin is much much higher.

I have a geo thermal heat pump and the unico system installed. We have radiant heat in the floor for the most part and of course the blowers for AC. Everything works. The system heats and cools the house very well, even in the large downstairs, 1200 square feet where we have a dining room connected via pocket doors to the kitchen which is then connected to the living room with a large arch. The return for the whole floor is in the living room. I do have to say, however, that the system is incredibly expensive to operate. My electric bill runs from $300-800 per month. The lower costs during fall and spring when the system is not running as much for either heating or cooling.

The house is insulated and has new windows, no drafts.
My energy bills were less with gas heat and radiators and wind ACs in the rooms used as needed. Whole house heat or cooling is a waste of energy and I am disgusted.