Marta Kelly, the company's vice president of finance and customer service, said the utility originally budgeted to install 200 heat pumps this year.
But after overwhelming demand, Kelly said Saint John Energy has now installed more than 300 with another 100 possible future installations.
"We were overwhelmed with the demand and very excited that we were able to offer something that obviously customers were looking for," said Kelly.
The utility first introduced the rental program in the middle of January. After an assessment, customers are offered a range of three different sizes of heat pumps based on their needs.
The most expensive heat pump offered costs $49.99 plus tax a month.
Kelly said the plan for the program was to open the field to customers who may not have been able to afford to buy a heat pump outright. A single unit can cost around $4000 installed.
Homeowner Andrew Sabin says that is what had been keeping him from installing one in his home.
"For a good unit, you're sometimes in excess of $5,000," he said. With the rental heat pump replacing his baseboard heaters, Sabin said the cost of heating his 1,000 square foot home is noticeable.
Even with the rental fee "the savings are immediate," he said.
The rentals are also appealing to those wary of making the switch to something different.
Cathy Goodwin was unsure if her two-storey home could be kept warm with a single heat pump.
After an assessment, she was told that she could swap her nine baseboard heaters for a single unit.
Now, Goodwin said she's "amazed that it's very comfortable downstairs and very comfortable upstairs as well."
Moncton-based Atlantic Heating and Cooling is in charge of installations and servicing the rental units. The company has a Rothesay office and had to bring in more workers to keep up with the demand.
The maintenance required on any of the rental heat pumps is covered in the monthly fee, which is why Stephen Brittain decided to have more than three dozen of them installed in the apartment building he co-owns.
"Cost was not a huge consideration, because one way or another, you're going to pay" said Brittain.