By Andrea Arnold
Dunster resident Ken McNaughton installed a geothermal heating system into their home in 2014.
Prior to the installment, they had been heating their home with wood heat through an outdoor furnace.
McNaughton had installed a few for others in the area and decided he should have first hand experience with the system if he was going to continue. He also completed three training courses, one in Kitchener, Ontario and the other two in Calgary, Alberta.
McNaughton opted for geothermal heat instead of going for a heat pump that pulls heat from the air.
“The ground provides a more consistent temperature than the air,” said McNaughton. “The fluid coming into the house holds a pretty steady temperature around 32 degrees fahrenheit regardless of the air and surface temperature. The water in the system gets up to 120 degrees fahrenheit.”
The system they needed in order to completely heat their house was unique in that they needed two different types of heat, both forced air and in-floor.
In order to pull the heat from the ground, McNaughton dug six trenches seven feet deep out in a nearby field, and laid thin wall geothermal tubes in each trench to create what is called a loop. The tubes are filled with a water and methyl hydrate fluid, 75/25 percent split. The methyl hydrate acts as an antifreeze, preventing the fluid from freezing.
The fluid flows into the house and into the geo unit (heat pump) where it undergoes a reverse refrigeration process. Heat is exchanged (removed from) the antifreeze like fluid and transferred into stored water that is cycled from the water storage tank. The water/methyl hydrate is returned to the trench loop where it gathers more heat.
This is where the McNaughton’s system varies from the others that he installed. From the water tank, the hot water travels in two different paths.
For the in-floor heating the water is pumped from the tank, and through the floor system before returning to the tank.
For the forced air system, the hot water enters a triangular radiator that is located above a large fan.
The fan blows air across the radiator and into the ducting to distribute warmth throughout the house.
In order to install the horizontal loop system, a large portion of land surface is required. The option for a vertical loop is possible. It required holes drilled to approximately 150 feet so it is used for more urban or populated areas. The size of the unit needed to provide adequate heat determines how many trenches or holes are needed.
McNaughton says that there is very little regular maintenance needed for these systems. In his case, with the two types, he has to clean the air filter and check the water level in the storage tank.
The whole system uses about a quarter the electricity or 30 amps, that an electric furnace uses.
“Our hot tub uses the same amount when it is on,” said McNaughton.
He says it costs about $200 a month to keep it running.
A geothermal heat pump system has a life expectancy of about 30 years. McNaughton has had his for 10 and has no regrets about making the switch. As McNaughton has been out of the business for a few years, he would guess that the cost of supplies and installation would be over $30,000.
Both of these systems can be switched to provide air conditioning. The forced air temperature can be switched to cooling by the flip of a switch. The water-to-water that provides the in-floor heat requires a more complicated process to activate a reverse valve within the geo unit.
“For the week or so out of the year that air conditioning would be nice here, it isn’t worth the work,” said McNaughton.
