After we installed our Mitsubishi, ductless mini-split, we were using it exclusively to cool our house. The unit we installed is a 2-ton, single head. It really is not designed to cool an entire house, but we wanted to see what it could do. We were seeing over 30% savings on our electric bill during the spring. As summer kicked in, our savings dipped a little bit but never got below 20% savings.
Because the system is a single-head, it is not designed to cool the entire house; so if doors were closed, those rooms would get hot. A multi-head system would take care of this problem.
Since the beginning of August, we have turned on our central A/C system, and the mini-split is being used as a supplement. We just got our latest electric bill, and we are still seeing substantial savings. This latest bill is for $164.77. Last year it was $217.10. That is a savings of $52.33 or 24.1%.
So over the last 7 months we have saved $374.29! That averages out to 27.4%.