We live in Canada....cold winters. I have a bungalow on a 4ft slab...approx 2600sq ft living space inc the garage. It is a hydra electric boiler for our infloor heating....only source of heat. House was just built a year ago. If the power was to go out like several years ago for 4 days what should we have as a backup......would it only be generator......I need it to run 20 kw if Im not mistaken. Any information would be appreciated.