When the Lambe family moved to Burlington this past winter, neighbors couldn’t help but wonder what was going on.
There was a drilling truck parked in the yard —an unusual sight in these parts— and it sounded like work was going on in the backyard. Andy Lambe, who is a scientist by profession, said, “Before we moved in, our new house was an active construction site for about three weeks.”
Soon the word spread that the new neighbors were having a geothermal HVAC (Heating-Ventilation-Air-Conditioning) system installed in their home — a house that was built in the 1960s — and oil would no longer be needed for heat.
How did Lambe know a geothermal system would work? “My father, who is an engineer, had one installed over 10 years ago and it works great at his house [in Bristol County] so I knew it would work at ours,” he said.
How it works
A geothermal system is designed to take advantage of the solar energy stored in the earth.
The year-round ground temperature below the earth’s frost line is constantly in the 55-degree range. A geothermal system takes advantage of that consistency to transfer heat from the house during the summer when outdoor temperatures are above 55 degrees, and bring heat into the house in winter when outdoor temperatures are below 55.
The basic components of a geothermal system are:
· Underground loops of plastic piping
· A water/antifreeze solution
· An indoor heat pump
· An air distribution system
The heart of the system is a heat pump that replaces the furnace and a ground loop (a series of underground pipes connected to the heat pump). The pipes travel vertically several hundred feet below ground and are filled with an environmentally friendly coolant. It is a closed loop system, meaning that the coolant never escapes from the piping that is designed to last for 50 years.
During summer the heat pump removes the heat from the hot air in a home through a heat exchanger, transferring it to the coolant in the ground loop. That cooler and conditioned air is then distributed through the vents. The heat is removed from the coolant to the earth as it flows through the ground loop.
During winter the heat pump compresses the earth-warmed coolant, increasing its temperature to about 160 degrees, and then extracts the heat from the coolant and transfers it through the heat exchanger to the house air.
The heating and air-conditioning requirements for a home determine the size of the heat pump. Target room temperatures are 70 degrees in winter and 75 degrees in summer. For that reason it is best to have a contractor design the system.
Likewise, the size of the ground loop is based on the size of the heat pump, the climate and soil conditions. Dense clay soils have the ability to hold heat and transfer more of it. Sandy soils hold less heat and therefore require a larger loop field.
Lambe said that his home’s vertical ground loop required the contractor to drill down 515 feet to satisfy the requirements of his 2,500-square-foot home.
According to the contractor the Lambes hired, there are no other geothermal systems installed in Burlington.
How water is heated
Heat pump systems are available with an auxiliary heat-recovery system called a desuperheater. It is another condenser that is connected to a standard electric-water heater. During the summer, when the system is in cooling mode, almost all hot water needs are supported by the desuperheater. During winter it assists, reducing use of electricity.
Breaking down the installation activities, the Lambes had to have holes drilled for the ground loop system, trench the piping to and through the foundation, dismantle the old heating system and install ductwork.
The total cost for a geothermal system like the Lambes is in the $20,000 range. However, the cost is significantly reduced by alternative energy tax credits offered at both the state and federal levels.
Is geothermal right for you? Give one of our sales associates a call today for a free estimate.