Electric Heat Pumps

I have replaced my AC system with electric air heat pumps.

I have replaced my heating and cooling with Mitsubishi electric heat pumps. I have a central heating and cooling system in my house (really it is two identical systems for top and bottom floors). The heat used gas and the cooling was done through two A/C units on my white roof. I have decided to electrify it, and replaced the entire system with electricity-only heat pumps. Inside the house I have an air handler and outside the house I have two condensing units. The coolant is circulating between the air handlers and the condensers via silver insulated hoses. You can see the outside condensers units in this picture.

Mitsubishi H2i split systems model SUZ-KA18NAHZ. Each system is rated 18,000 BTUs

Now that I no longer have A/C units on the roof, my system is absolutely quiet, just air moving. No more noise or vibration on top of my bedroom. The system is pretty much silent, even the outside compressors are almost impossible to hear even standing next to them. The entire install took 2 days and was done by the Boston company SumZero Energy Systems. They have done a marvelous job removing my old system carefully and fitting the new one. I found them through the EnergySage website - they were one of the companies that contacted me, sent a person to evaluate the house and gave me a quote. I definitely recommend SumZero to everyone.

Bonus: the heat pump unlike gas does not constantly pump dry hot air into the house, thus the air during winter is much more pleasant with good humidity. When using the gas heater I always had dry skin and was zapped by static electricity. With heat pumps the air feels normal.


Before getting the system, I went through Mass Save program. Once I applied, they sent a person to do an energy assessment to my house. Luckily the house is pretty well insulated, so nothing had to be improved before I could transition to the heat pumps.

The entire system with installation cost me $28k. Massachusetts gives $10k rebate for the complete electric installation. The remaining $18k was financed by a long-term 5+ interest free Mass Save loan via a participating bank. With inflation, such loan is a very good deal. Monthly bills remain to be seen, but I have seen an estimate that today in Massachusetts modern heat pumps would be 13% cheaper to use than gas to heat a well-insulated house. Regardless, I do enjoy the quiet climate comfort plus knowing that I am not burning fossil gas to heat my house.

Remains to be electrified

I would love to electrify my water heater and replace the fossil gas stove with an induction stove. Unfortunately, I have maxed out the electrical capacity running into my house. If I want to run an induction stove plus have an electrical water heater, I would need to upgrade the power line feeding into my house plus upgrade the fuse box. This is currently very expensive.

For more about electrifying United States, see this website https://www.rewiringamerica.org/

Update 1: Electricity usage

Let's compare the electricity usage month-by-month compared to the last year before the switch. The electricity usage went up. For example, during January, February, and March we used 2.5 the previous amount of electricity.

Electricity usage monthly (kWh)

Let's take the look at the numbers

Month Before install (kWh) After install (kWh) Increase (times)
October 296 432 1.5
November 352 638 1.8
December 432 908 2.1
January 448 1231 2.7
February 406 1066 2.6
March 354 889 2.5

Remember: my electricity comes from Clearview Community Solar Farm so I pay less money than the normal Eversource rate.

Now let's look at the gas usage.

Gas usage monthly (thm)

Wow! The gas usage went down. I still use gas to heat the water and cook, but the main portion was burning gas for heat. The same months in the table:

Month Before install (tmh) After install (tmh) Decrease (times)
October 29 17 1.7
November 47 20 2.4
December 77 29 2.7
January 95 28 3.4
February 79 23 3.4
March 81 22 3.7

If only I replace my gas water heater with an electric hybrid heat pump, I bet I could get my gas usage to almost nothing!