We're in central MA, Worcester County out in the country. Are you referring to your natural gas bill or are you on propane? We don't have natural gas out in the country, so it's either deliveries of oil or propane, or electric from the street.

Yeah, that's pretty much the direction we're heading: Cold weather heat pumps are primary heat, need backup heat when it's too cold for heat pumps, need some source of hot water (same fuel/system as backup boiler, or something entirely different?)... Sounds like we may be on the right track...

The HVAC guys are telling us a combi unit wouldn't work well for our usage, so they're looking at tankless water heater as one unit, backup boiler as a separate unit... but we did ask about the combi units.

Haha, noted... HVAC guys are all quoting out for Mitsubishis or Bosch heat pumps, so sounds like I'm in clear there :)

Interesting... as in, you paid just as much in electricity for both? The heat pumps are supposed to use less electricity, so would be interesting if your experience was otherwise...

Yeah, small gas generator is still a possibility... but storing enough gasoline for a protracted outage is more difficult than storing propane, and propane generators can automatically kick on vs. gas I have to be home to go wheel it out and plug it in and flip circuits, etc. So there is some benefit to a propane fired generator for emergency power. Someday I'd love to be solar+battery/PowerWall... may not be in the cards for this house specifically.

I agree philosophically on this... If I could get all-electric with solar we would. We did the assessment at my last house and we couldn't quite generate enough off our roof to cover our needs and pass excess to the grid. I need to have a proper assessment done on my new house here, but I don't have high hopes as we don't have any south-facing roof area... Half of our roof gets the morning sun, the other half gets the afternoon sun, and some of our roof is shielded by some trees in the wintertime when the sun is lower. Pending expert assessment, it looks like we won't get much generation off our roof. The fallback is putting panels in our yard, but we like using our yard for play area.

Hi, yes, we're working with HVAC companies to put in heat pumps which will become our primary heat source instead of our oil boiler... But every HVAC company has recommended we keep a backup heat source in case it gets too cold for the heat pumps, or if there is a breakdown in the heat pump equipment that can take a few or several days to repair and we wouldn't want to be without heat in the meantime... Since we have existing radiators from our boiler, they're all saying keeping a boiler as backup will be the best option... but our boiler is near end of life, and not providing enough hot water, hence this whole line of questioning and research about oil boiler vs. propane boiler.

I just stumbled into the idea of Heat Pump Water Heaters today too... Interesting idea... Consumer Reports show them being far more efficient and far better ROI/pay-back then either gas or electric tanks or tankless. I'll drill into that idea more as I pursue this.