[disclaimer: I am a heat pump technology developer, however the following is just low-effort notes and mental calcs of low reliability, they may be of interest to some. YMMV]
It may be better to invest in improved insulation.
As rough rule of thumb COP is = eff * Theat/(Theat-Tcold), with Temperatures measured in absolute degrees (Kelvin or Rankine), eff for most domestic heat pumps is in range 0.35 to 0.45, high quality european units are often best for COP due to long history of higher power costs—but they are very expensive, frequently $10-20k
Looking at the COP for the unit you quoted the eff is only about 0.25 at rated conditions, not good, unless you get a much larger unit and run it at a less powerful more efficient load point.
That’s a pretty huge electricity price, about 4.5x gas price (which is distorted-market nuts, 3x is more usual globally). Given that differential it might be better to look at an absorption heat pump like https://www.robur.com/products/k18-simplygas-heat-pump that gives up to 1.7x gas heat—though they look to be on the order of $10k.
Here’s an annoying fact; If you ran that $2/therm gas (~$0.07/kWh) through a reasonably efficient (~40%) natural gas genset it would produce electricity cheaper than what you currently pay for power, and you would have 2/3rds of the gas energy left over as heat. A genset in your neighbourhood could provide a few 10′s of houses with cheaper electricity and low cost waste heat, though no doubt prevented by regulatory issues. There are a few small combined heat and power (CHP) domestic units on the market, but they tend to be very expensive, more tech-curios than economically sensible.
If you ran that $2/therm gas (~$0.07/kWh) through a reasonably efficient (~40%) natural gas genset it would produce electricity cheaper than what you currently pay for power, and you would have 2/3rds of the gas energy left over as heat.
I was curious about this, and here are the numbers I got. I looked around and even a 23% efficient Generac 7171 comes out ahead. It’s rated for 9kW at full output on natural gas. They say it uses 127 ft3/hr which is 1.37 or 39kWh. This is $0.304/kWh.
Of course this ignores the cost of the generator, maintenance, lower efficiency when run below full capacity, etc. but it’s still pretty weird!
Yeah, I came to say the same. You’re basically running into the problem that electricity in MA is expensive relative to natural gas, which is very much a contingent fact of policy/history/infrastructure. If you were living elsewhere, or living off-grid, the numbers would look very different.
You may (or may not) find the MA policy mix and cost structure changing in the future, so if nothing else, be ready to revise your numbers over time. Especially if your current gas system breaks and you have to replace it with something no matter what, that can change the economics a lot too.
Seconding the importance of insulation, especially for disaster preparedness and weathering utility outages.
If any of your friends have a fancy thermal camera, see if you can borrow it. If not, there are some cheap options for building your own or pre-built ones on ebay. The cheap ones don’t have great screens or refresh rates, but they do the job of visualizing which things are warmer and which are cooler.
Using a thermal imager, I managed to figure out the importance of closing the window blinds to keep the house warm. Having modern high-efficiency windows lulls me into a false sense of security about their insulative value, which I’m still un-learning.
[disclaimer: I am a heat pump technology developer, however the following is just low-effort notes and mental calcs of low reliability, they may be of interest to some. YMMV]
It may be better to invest in improved insulation.
As rough rule of thumb COP is = eff * Theat/(Theat-Tcold), with Temperatures measured in absolute degrees (Kelvin or Rankine), eff for most domestic heat pumps is in range 0.35 to 0.45, high quality european units are often best for COP due to long history of higher power costs—but they are very expensive, frequently $10-20k
Looking at the COP for the unit you quoted the eff is only about 0.25 at rated conditions, not good, unless you get a much larger unit and run it at a less powerful more efficient load point.
That’s a pretty huge electricity price, about 4.5x gas price (which is distorted-market nuts, 3x is more usual globally). Given that differential it might be better to look at an absorption heat pump like https://www.robur.com/products/k18-simplygas-heat-pump that gives up to 1.7x gas heat—though they look to be on the order of $10k.
Here’s an annoying fact; If you ran that $2/therm gas (~$0.07/kWh) through a reasonably efficient (~40%) natural gas genset it would produce electricity cheaper than what you currently pay for power, and you would have 2/3rds of the gas energy left over as heat. A genset in your neighbourhood could provide a few 10′s of houses with cheaper electricity and low cost waste heat, though no doubt prevented by regulatory issues. There are a few small combined heat and power (CHP) domestic units on the market, but they tend to be very expensive, more tech-curios than economically sensible.
I was curious about this, and here are the numbers I got. I looked around and even a 23% efficient Generac 7171 comes out ahead. It’s rated for 9kW at full output on natural gas. They say it uses 127 ft3/hr which is 1.37 or 39kWh. This is $0.304/kWh.
Of course this ignores the cost of the generator, maintenance, lower efficiency when run below full capacity, etc. but it’s still pretty weird!
Yeah, I came to say the same. You’re basically running into the problem that electricity in MA is expensive relative to natural gas, which is very much a contingent fact of policy/history/infrastructure. If you were living elsewhere, or living off-grid, the numbers would look very different.
You may (or may not) find the MA policy mix and cost structure changing in the future, so if nothing else, be ready to revise your numbers over time. Especially if your current gas system breaks and you have to replace it with something no matter what, that can change the economics a lot too.
Seconding the importance of insulation, especially for disaster preparedness and weathering utility outages.
If any of your friends have a fancy thermal camera, see if you can borrow it. If not, there are some cheap options for building your own or pre-built ones on ebay. The cheap ones don’t have great screens or refresh rates, but they do the job of visualizing which things are warmer and which are cooler.
Using a thermal imager, I managed to figure out the importance of closing the window blinds to keep the house warm. Having modern high-efficiency windows lulls me into a false sense of security about their insulative value, which I’m still un-learning.