Those mini-split room AC+Heater units come in larger sizes,
http://ecorenovator.org/forum/projec...l-project.html
which are suitable for whole-house heating and cooling..
Our 24k BTU cooling+ 36k BTU heating Sanyo mini-split works very well with our small (insulated) home.
IMHO, the inverter type mini-split AC/heater has a very big economic advantage over American style HVAC 'central' systems..
Combined heating and cooling system cost is less.
Installation cost of a ductless system is much less.
Operating cost is much less when compared to almost anything else.
It's almost as good as geothermal GSHP systems for power useage,
and better in the areas of equipment cost and installation.
It's the poor man's geothermal GSHP..
Cheers,
Rich