Potseal, as I see it, the joker in the sizing decision is the starting current required for motors. When your overall load is as small as mine - or when, in my case, all I'm powering right now is one motor - that starting current matters.
Now, my generator, even when bought at a bargain price, cost me more than many similar capacity generators that I see in some retail outlets? Why pay more? Well, the biggest differences are in the noise made and the reliability of the voltage regulation.
There's my concern about voltage spikes: the voltage regulation of the generator as loads change. I would hate for a high-voltage spike when the furnace motor stops to cause harm to any electronics that might be on line.
Yes, a UPS would help; I had forgotten about that. That might be a solution.
Greg, I'd love to see what actual measurements show.
