As a home inspector, I am often asked about heat pumps and their costs versus traditional systems. I installed a heat pump last year and have compiled some results.
We are a family of five that heavily relies on energy to heat and cool our Maine home. Was a heat pump the answer after one year?
First, a little background:
We live in an 1800sf home built in the late 1970s. We have an oil fired furnace that we installed in 2006 and service annually. This furnace creates our heat and domestic hot water (with an indirect water heater that stores 50 gallons of heated water), so we burn heating oil all year. For supplemental heat, we have a propane fireplace (doesn't do much other than keep my wife warm on a Sunday afternoon) and a Rinnai heater in my office that is not part of the main house. In summer months, we used two window a/c units before the heat pump was installed. One was large (15k btu) and another was pretty standard for the second floor. Both were used regularly in July, August, and September.
In May 2022, we installed an 18,000 btu single heat pump in the main part of our first floor, serving our living area and kitchen. This is where we spend most of our time. By single heat pump, I mean we have one head installed that blows heat in winter and cooling in summer. Other heat pump options exist that have multiple heads throughout the home. We were trying to reduce our energy usage with a low up-front cost. As you can imagine, a heat pump that heats more area will cost more.
My Not-So-Scentific Analysis:
Now, I don't have all the data, but I have enough for me to understand the initial impact towards our primary goal of heating oil reduction. Aside from the adverse environmental impact, I'm hyper-focused on reducing energy cost. As oil prices constantly change, our annual costs fluctuate by hundreds if not thousands of dollars each year. I'm a planner. I don't like volatility. Propane can be just as volatile, but our consumption is significantly less as its purely supplemental.
Our average pre-heat pump annual consumption (2019-2022):
Heating Oil: 756 gallons per year
Propane: 294 gallons per year
Electricity: 9,241 kw hours per year
I'm simply looking at energy consumption, not cost. I want a real apples-to-apples comparison that shows energy reduction, not price reduction. All else is relatively constant over this period as well:
According to NOAA, average Maine temps are relatively constant over the period
My family of five still has one at college and four living here year-round
No significant changes in lifestyle - no welding or high-electricity hobbies...
Only material insulation improvement (attic) happened just three weeks ago
The Results:
To my pleasant surprise, our oil consumption over the past 12 months declined by 37%, or 276 gallons (roughly one tank). I just filled up this morning to get a true year-over-year picture as I filled up at the same time last year. Given the price of oil I paid this morning of $3.96, our savings is $1,093. Not bad.
Now, how did my electricity usage change? I expected it to increase as the heat pump is 100% electric. Actually, no. We saw a 9% reduction in year-over-year electricity usage, or 857 Kw hours saved. At today's rates, about $189 was saved. All of the kw hour reductions were in summer months as I replaced the energy-sucking A/C units. Usage increased during colder months, but not enough to outweigh the summer.
Our total saved is close to $1,300. On top of that, our propane usage was constant and our heat pump was able to reach our thermostat setting without trouble.
We keep the house at 68 (second floor at 62) and the heat pump ran constantly to maintain that temperature. We kept the furnace thermostat at 66 to only kick in when the heat pump couldn't needed help. On the few cold stretches we had, you could hear the furnace engage a bit more (remember...hyper-focused to the point of being counter-productive).
To complete the analysis, the cost of out heat pump was about $2,000. I did the work myself and it was relatively simple as a DIY project. Only do this if you're comfortable taking on a large project (and have a network of REAL professionals to help, if needed). Never do electrical work yourself. The risk is too great.
For those reading this who have already installed a heat pump, here is a list of things we did to make this successful:
Set it and Forget It: Keep the heat pump at one constant temperature. Traditionally with a furnace, the settings rise and fall as we are home or not. Heat pumps keep their efficiency by maintaining one temperature all day, every day. In fairness, we kept a winter temperature and a separate summer temperature.
Location is key. We have our head in a large room, blowing directly into another large area and eventually into a less-used part of the home. Do your best to optimize airflow. Listen to the installer and his/her recommendations.
Always install according to local codes and keep the outside condenser unit at least 10' away from any fuel source (propane tank, for example) as the condenser is an ignition source. Your propane company knows this and won't deliver if you're within this range.
Not all heat pumps are created equal. SEER ratings are a way to measure the efficiency of a unit. Some units struggle more than others in colder temperatures. Huge advancements have occurred over the past 10 years and more improvements can be expected. As of this post, a SEER rating of 21 is pretty great. Ours has a rating of 20. Some go as low as 13.
Our next step is to install a heat pump water heater to join our indirect water heater. In winter when the furnace is running regularly, it makes sense to keep our indirect water heater rolling via our oil-fired furnace as it's already running. In summer, I'd prefer to not use the furnace at all and convert to the electric water heater that will also dehumidify as it makes the hot water, reducing one more appliance in my basement. This could further reduce our oil consumption by another 100-150 gallons.
We'll see. I'll keep you posted.
Thanks for reading,
Matt