Comment Re:i bought a heat pump before they were cool (Score 1) 155
Exactly, the sweet spot (for natural gas) is about 40F to 45F Outside, as natural gas (here) is generally about 1/3 the cost/btu as electricity (and sales tax is not charged on heating fuels in the winter - but you can only have one fuel designated as a heating fuel). I would think someone who has to use propane or oil (or even wood) would have a sweet spot at a much lower temperature; as, those fuels are much more expensive. You always need a backup to the heat pump. Resistive heat is a good choice if you don't think you will ever need it.