If there were a Cadillac of heating and cooling systems, it would be the geothermal heat pump.

It's expensive like a luxury car, but uses fuel like a motor scooter. And that means it saves you lots of money, while keeping your home nice and toasty.

In part three of our "Heating your Home for Less" series, we take an up-close look at a geothermal system.

It might sound too good to be true: one system for year-round comfort. There's not even a backup heating unit for the really cold days. And, it uses energy that is right in your backyard.

“This is a heating system, a cooling system in the summertime and it also provides our hot water as well, so it’s an all in one unit,” said John Sherrick, who uses a geothermal pump. “It can do everything.”

Unlike an air source heat pump that has to work harder as the air gets colder outside, a geothermal system is always working with the same ground temperature. In this system, 50 degree water is pumped out of the ground, and using a heat exchanger, a refrigerant like freon is warmed up. As the water is recycled back into the ground, the refrigerant becomes very hot and travels inside to another heat exchanger.

Inside air is then heated and blown into the home. The cooled refrigerant then travels back outside to pick up heat again from the ground water. The only energy you pay for is electricity.

Your typical electric range in a kitchen puts electricity through wires and they heat up and become red and that's putting off a lot of heat. A geothermal system actually gets five times that amount of heat out of the same electricity.

“Last year, this is something my wife would always kid me about, we would turn the thermostat down at night, and we would keep it at 66 degrees at most,” said Sherrick. “And when family and friends came over for visits, and the holidays, it was an ice box in here. We just couldn't afford to turn it up because the cost of propane was too expensive.”

John and his family wanted a change, and they decided on a geothermal heat pump. So far they don't regret it at all.

Last winter, the Sherricks spent over $2000 dollars to heat their home using propane. The electric bill was $490 during the heating season. Here's what we definitely know: the propane bill will go to zero. And we're estimating that the electric bill will increase by just $450. That's a huge savings of almost $1600 with today's prices.

The total cost of the geothermal system is high, this one was $14,000, although financing allows you to spread the cost out. With these numbers, just during the heating season it would take 8.8 years to pay back the total cost. If you calculate in the estimated savings for air conditioning and hot water, though, you get it down closer to 5 years. And you never have to worry about rising fuel prices again.

This particular system is best for a country home, but there are geothermal systems suited for city-dwellers as well.

As with the high-efficiency furnace and heat pump, we're going to follow up on the utility bills on the geothermal pump this winter, and bring you updates on the savings.

And for more good links on how to "Heat your Home for Less," click on the Big Red Bar.