Annual Heat Pump vs. Furnace Energy usage 2024 Update

Hot_water_fan

I posted one of these last year, it's updated with the 2023-2024 time period. The furnace was used from November 2020 to mid Feb 2021, then replaced with a heat pump. This is how much electricity and gas was used during that time period, and the 3 following time periods.

The change from previous years to 2023-2024 was that in spring 2023 the gas water heater was replaced with an electric resistance water heater, adding about 6-7kwh/day of electricity to the bill.

• It is remarkable how little variation in heating degree days these 4 periods have.
  
• I think the coldest temp this winter thus far was 7F or 8F.
  
• COP for these months is probably ~3.
  
• COP for the entire winter, which I define as when the heat is on, is probably higher since October and March are warmer on average. On average, there are about 3000 Heating Degree days (base 60F)/12-month season (starting 11/1), so about 1/3rd of the heating season is yet to happen.
  
• It is extremely challenging to compare costs. The calculation is simple, but the utility changes so many costs every month and I've signed up for other energy suppliers, comparing apples-to-apples is difficult. The direction is easy (the heat pump is cheaper) but exactly how much cheaper changes a lot. Right now, it's about 33% cheaper. It'll change in a few days when gas prices change for March. I don't want the point of this exercise to be about costs. They'll change constantly. They're different for other people. We all know this.
  
• The electricity used for the DHW is lower than I expected. The two years with the heat pump and gas tank averaged 5.8MMBtu input, estimated output of 3.5MMBtu. This year, only 2.4MMBtu of electricity was added. Maybe I'm showering 33% less? Hopefully not.
  

ethicalpaul

Very cool. DHW just isn't that expensive regardless of fuel. No matter how much I like my heat pump water heater, I can't escape this reality

Hot_water_fan

@ethicalpaul yup the bar for a HPWH is pretty high when usage and electricity costs are low. My off-peak rate is $.11/kwh, so it's tough to make a HPWH work.