Upgrading an old oil furnace and AC unit to a new high efficiency heat pump has been one of the two keys to making my family's home in PA produce more energy than it consumes (the other of course was adding a big fat solar array). Now that we've lived in the house for over a year I thought it would be a good time to look back at the data and see what sort of return on investment (ROI) this heat pump has given us.
Incredibly janky port of comments from my old wordpress site.
2022-03-29 at 6:21 pm
I appreciated reading this article. I am currently looking at replacing oil heat and hot water ROI of a cold climate air source heat pump and standard electric heater. I factored in all savings I could, including reduced insurance, reduced maintenance and potential increase in home value to a buyer and came up with an ROI of about 11 years. (the upfront costs are very high, less a govt incentive). There are other non-tangible factors to consider too – reduced risk of catastrophic oil leak, savings from not having to replace the furnace in the future and of course, just the feel-good going green component. This is what I calculated in savings for my home in northern Ontario (we don’t currently use AC other than a small portable so this is just a guess)
Fuel savings heat 534.42
Fuel savings hot water 435.51
savings burning less wood 250.00
savings maintenance 350.00
insurance savings 25.00
Additional cost of AC -300.00
total annual savings 1294.93
2021-10-06 at 12:33 am
I enjoyed your article and analysis. It was timely as I live in Southeastern PA (Lancaster County) and the AC and Propane Furnace is approaching 20 year of age. I had been thinking about replacement of both with a heat pump but my experiences while living in Georgia on some cold days were not very positive as the heat pump on very cold days would not keep the house warm and comfortable. I was worried if that might also be the result in PA. I was also wondering if the investment would be financially viable compared to our actual cooling cost and propane heating cost. Any help you might provide would be appreciated to get me headed in the right direction.
2021-01-19 at 5:33 pm
Absolutely love your site/blog, thank you. So glad I stumbled across it.
Love the way you think — put up a big fat array bc solar is so cheap, and don’t go crazy with changing appliances etc, electrify everything and get more panels if needed…
We live on a farm in the Upper Peninsula (UP) of Michigan. Cold and snowy. Avg high temp in 20’s and low 30’s Nov-March and only 60’s and 70’s May-Sept. Our big need is heating not cooling, but cooling is great for our rare southern flow with hot muggy days.
Low sun and lots of clouds in the winter. Long days and much “overproduction” in spring, summer, fall.
We are installing a 30kW array. As you note, panels and cheap. We have space so are doing a ground mount. Building own racking, single-axis tilt — will have up near 70 degrees in winter to see the sun and shed snow. Free and clear 180 view south from array (on bank of E-W creek). Also will have 10kW of VAWT to help in the winter when it windy and not sunny. Will run 2 EV’s off system, hopefully with V2G capability so we’ll have batteries.
We have a wood stove with free firewood (375 acres of maple and oak) to take the place of supplemental resistive heat when the heat pump will need help on the sub zero days.
I have a loader-backhoe, so there is not much extra cost for doing a ground-based heat pump, and we really need one to get 45-50 degree ground heat vs typical single digit or teen low overnight temps (and especially when it goes negative for several days).
So here is my question, finally: knowing we like to oversize, knowing that it’s a very large but modernly insulated farm house (6,500 ft2 — it’s gonna be a B&B when we’re done), knowing we can cheaply install a ground-based heat pump (and love having it the basement not outdoors all winter!), what make/ model/ size gb heat pump would you point me too? And would there be something like a mini-split in each room/ space that would work with the gbhp?
2020-11-28 at 5:29 pm
I live in San Jose, California where our climate is probably much milder than where you live. The average summer high is in the mid 80 degree range. However, in July and August it can easily reach the low 90 degrees. Very rarely does it ever go over 100 degrees. San Jose is also not very humid. So a slightly warmer temperature is not that uncomfortable. In the winter a “bitterly cold day” is around thirty degrees. Most seasons it never goes below freezing. However, usually nighttime temperatures in the winter are in the 40 or 50 degree range.
Our 1964 house still has the original gas “80 percent efficient” 100,000 BTU gas furnace. However, I understand that it is probably less efficient than that due to an inevitable loss of efficiency as it ages. I have no air conditioning. However, our house can get uncomfortable for two or three months in the middle of summer. I did a manual J analysis and it showed that my 100,000 BTU furnace was much too large and my ducts are to small for a modern day furnace of that size. In addition, about a third of the house is served by only one duct. That means that the upstairs heats up in a few minutes and the downstairs is perpetually cold during the heating season.
Electricity is very expensive hear. I have an electric car tariff so my rate is relatively low most of the day (at least for California). As you can see, the tariffs during peak times 4:00 PM to 9:00 PM are outrageously high! Part peak is from 3:00 to 4:00 PM and from 9:00PM to 12:00 AM with rates only moderately better.
Total Energy Rates ($ per kWh) PEAK PART-PEAK OFF-PEAK
Summer Usage $0.47925 (I) $0.36876 (I) $0.16675 (I)
Winter Usage $0.35214 (I) $0.33544 (I) $0.16675 (I)
Delivery Minimum Bill Amount ($ per meter per day) $0.32854
California Climate Credit (per household, per semiannual payment occurring in the April and October bill
Surprisingly, we have lived in the house nearly 25 years and we have never had any problems with our furnace.
I have been considering replacing my furnace with a new smaller furnace. In part because a newer furnace would would use less energy and partly because a smaller furnace would run for longer periods so that the warm air would be more evenly distributed throughout the house. However, I doubt a new furnace will ever pay for itself.
I have also considered changing my furnace to a heat pump. However, my concern is that because of my high electricity tariffs, I will have much higher utility bills if I switch from a gas furnace to an heat pump. My reasoning is that much of the heating and cooling would occur during times when peak rates are in effect.
I have also considered adding a mini split downstairs instead because the ducts downstairs are limited to one register which is completely inadequate. I could then wait to replace the gas furnace until it breaks down.
I have also considered adding solar.