If you’ve been hanging around Acadia Center’s blogs for very long, you’ve heard about how air source heat pumps work by moving heat, rather than generating it – so they can be 3-4 times as efficient as gas, and how “a heat pump is probably the biggest thing that consumers can to do help fight the climate crisis.” You might have even seen my colleague Ben Butterworth’s multiple photos in the Boston Globe as the face of heat pumps, or read about the lessons I learned back in May when investing in seven mini-splits to electrify my 1880s house.

But have you heard that under the Inflation Reduction Act, starting in 2023, heat pumps will be eligible for rebates and tax credits of up to $8,000, in addition to the rebates already in place from state programs like MassSave?

Here’s what I’ve learned from living with my heat pumps through one of the warmest summers in Boston, and into a fall that’s been both cooler than usual and repeatedly hit 70 degrees in November.

Power Cool: Even though this August was the hottest on record, my heat pumps kept my family comfortable and well air conditioned. Last year, we had one AC unit and a ton of fans to see us through August, and it was miserable. We spent too much time and money at the movie theater, mall, water parks, and other desperate ways to keep cool. This year, we happily spent our days at home in comfort. My daughter even discovered a “power cool” setting that sounded like a jet engine but felt amazing as it rapidly cooled her room. We did use 38% more electricity in August than the year prior but were easily 100% more comfortable, and spent roughly the same, once you factor in the movies and water parks. Although my home isn’t a good candidate for solar, I’m going to look into a community solar program, to be able to reduce our bills for next summer.

Dehumidification settings matter: My son’s asthma was flaring up late this summer and his room smelled even funkier than you’d expect for a 9-year old’s bedroom. I had a mold inspector come check things out. He didn’t find any mold but did find that the humidity levels in most of the house were 68-72%. Way too high. After some frustration, I dug into the settings on my heat pumps and discovered that the dehumidification mode (rather than the auto-cool setting I originally chose) resulted in a much lower humidity home with a much cooler feel. Better idea all around! So, watch out for humidity weirdness and play with settings. You may be surprised by what you find. Also run a full dehumidification cycle when you’re switching from cooling mode to heating season to make sure that you clear out all the moisture and prevent mold in the air handlers.

Keep it Clean: Although my instruction manuals said that I should clean the air filters monthly (and other filters periodically), I have only done it twice in the 6 months the heat pumps have been part of our family. Both times, though, there has been a lot more dust than I predicted. These things really are filtering the air! It’s important to keep the filters clean to maximize air flow, reduce the amount of energy they need to expend, and keep your air quality high. I’m going to put an alert on my calendar to make it more of a habit. I’d also encourage folks to install indoor units where they can reach them for maintenance – 10 feet into the air (like two of mine are) isn’t a great spot unless you love hanging out on ladders.

Shoulder season: I have been loving the flexibility that my heat pumps offer to heat up one room at a time or turn them on just enough to take the chill out of the air. With our radiators, it’s all or nothing and that first burst of heating inevitably wakes up my kids with all the banging. Especially on these days when it’s cold in the morning, but lovely by mid-day, I appreciate having the option to micro-adjust the temperature in my office or bedroom while leaving the rest of the house to float (because it also holds its temperature well after upgrading our insulation). And on the surprise 70-degree days, it’s nice to just turn the units off and not deal with residual heat like we would have with the radiators. As climate change makes our weather weirder, I’m glad to have equipment that can handle extremes in both directions and change up quickly.

Be a New Englander, Wear the Sweater: The first few days I tried to switch to heating mode, my heat pumps would run for a few minutes, then pause seemingly mid-cycle and show me an icon like a water droplet on top of a snowflake. This error message wasn’t included in any of the instruction manuals, and after some googling, I determined that it means that the outdoor temperature and humidity levels aren’t different enough from the indoor temp I’ve requested. In other words, my heat pump was telling me to suck it up and put on a sweater. It was right. Indeed, on the days when the temperature fell further, the error went away, and the unit started cranking out toasty warm air. I also remembered to lock closed all my windows, and that helped immensely, too.

The Financials: I got my full rebate from MassSave two months after it was submitted by my vendor. I’ve heard that it’s taking longer than in recent months because there’s been such a flurry of activity and rebate requests. Stay patient and keep checking the online tracker to see what’s happening. As I mentioned, my summer electric usage was 20-38% higher than last year (but we got a lot more AC out of the deal), but my fall usage has been within 15% of what it was. My gas use, however, was down 77% for the month of October. The biggest portion of my gas bills is now the $10 a month customer charge – indicating that once I get an induction stove and heat pump water heater, I can save even more by ditching gas entirely.

The Bottom Line: For me, the investment in heat pumps was more about comfort and doing what we could to decarbonize than it was about saving money. We have not saved much from the summer, but that’s to be expected with so much added air conditioning. I am excited to see how much we’ll save this winter! Check out the MassSave heating comparison calculator if you want to see the potential savings for your home. This year, I’m even looking forward to snow, so we can really see how the heat pumps fare and hope to make it through the winter without turning on our backup system. I’ll let you know in the spring!