HVAC in house without ductwork

[Debra R.]

Hi All! 

Maybe you can help me with an important decision about HVAC for a home we just bought. It is a 1950's ranch in CA near Sacramento. Currently it has no cooling system and the gas furnace only serves about half of the house and the ducting associated with it will most likely need to be removed. The reason the ductwork will likely need to be removed is that it was installed in an unpermited, poorly built, "attic" that was created by building an entire new roof with new trusses/rafters over the original one. The original roof was a typical ranch roof - long and low. The slope is slightly less than 3/12. The house has vaulted ceilings which we want to keep and a slab foundation so if we go back to the original roof there won't be any easy way to add ductwork.

The only option I can think of for adding both heating and cooling is the mini (multi?) split ductless system but I know very little about them.Some of the questions I have are:

1. Am I correct that a mini/multi split system can provide both heating and cooling?

2.Are these systems designed to only provide additional heating/cooling or can they handle the job on their own? The climate here is - average highs in the summer are 80's and 90's with some 100+ days. The average low in the winter is above freezing, but occasionally could go below freezing.

3. Is the difference between mini and multi split that the mini is designed to handle just one room or zone? and the multi will handle numerous zones?

4. Do they work ok in very open spaces? The living room, dining room, kitchen and breakfast nook are all 1 open space with a vaulted ceiling.

5. Are there other questions I haven't thought of to ask?  

We are planning to live in this house at least a couple of years while we continue to remodel it and so want to be sure it will be comfortable.