I have been known to take along a 2000 watt generator on a service call.My portable generator wouldn't start this morning. I moved it in to the shop and put the torpedo heater on it. This generator has a 15 hp motor on it and it's hard enough to start in warm weather.
when someone has their off grid generator out in the generator shed and it won't start because of cold I get my little one going and point the exhaust right at the frozen one...20 minutes or two cups of coffee later they usually start.