Westchester County, which includes some of the wealthiest ZIP codes in the state, has become a de facto testing ground for the state and the industry to persuade homeowners to adopt these air- and ground-source pump systems.

Con Ed, which announced its ban on new gas hookups in the county this spring because demand is outpacing gas availability, currently provides a $5,000 rebate for customers who buy a geothermal system from their partner Dandelion Energy. Combined with a rebate from the New York State Energy Research and Development Authority and a 30 percent federal tax credit, about $10,000 to $12,000 can be shaved off a system that can cost anywhere between $25,000 to $40,000 to purchase and install.

Adam Tucker, a Chappaqua, N.Y. resident, recently took advantage of the available savings to replace his oil-burning boiler that was over 30 years old. Mr. Tucker, an accountant, said he was floored when Con Ed gave him a $200,000 to $250,000 estimate (before the moratorium began) for him to switch over to natural gas. The hefty price tag included the cost for the digging and infrastructure work required to connect his home to the existing network.

“Who in the world would say yes to that?” Mr. Tucker said.

To look for a cheaper alternative, he started researching his options and came across Dandelion. With the available incentives, a $34,000 system was pared down to about $23,000.

Last winter, Dandelion and its partner companies took a few days to drill a hole about five inches in diameter and 500 feet deep right in front of his front steps to place the ground loops into the earth. Mr. Tucker’s system kicked in this January and he estimated that he has saved anywhere between $1,000 to $1,500 this year on his heating bill.