I fully expect the LP to kick in a morning or two at some point. It's going to take a ton of BTU's to heat this place in -30° temps for that long of a duration. It's times like this where I'm glad I have things setup the way I do. Peace of mind knowing the LP can kick in and out as it needs to while the Kuuma is doing it's thing. The LP furnace should also be glad (or is it us....LOL) to have the Kuuma, as I'm pretty sure our 75K BTU LP furnace alone would struggle to heat this place in -30° temps. In fact, they have been saying, in WI, heating systems are designed for -10° to -15°. If you have a programmable thermostat which lets temps fall when not at home they recommend you cancel it and keep house temp up throughout the day until the cold snap ends. Letting the house temp fall may result in the furnace not being able to bring it back up again. I also just got a reminder of this from my HVAC buddy, who normally keeps his set at 60° at night.