Geothermal
Geothermal or ground source heat pumps use the temperature of the earth to heat or cool your home, shop, or business.
Geothermal or ground source heat pumps (GSHP) use the relatively constant temperature of the earth to heat or cool your home, shop, or business. Ground source heating and cooling typically uses only the earth’s crust as a thermal mass in which to draw a constant energy from. As the earths crust is heated from Solar Energy, a properly designed and installed geothermal system has little or no geoimpact to the area in which it is installed.
In the radically changing seasons of the climate we have in Southern Ontario our clients can see temperature changes from sometimes -40C to +40C. This means that the HVAC (Heating Ventilation and Air Conditioning) systems need to accommodate this sometimes daily temperature swing. Geothermal heating is one of the best solutions in its inherent design to satisfy this condition.
To understand how geothermal works, a quick review of the different methods of how the unit inside of your home(typically referred to as a Ground Source Heat Pump (GSHP)) is coupled with the earth.
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Horizontal Loop: Where space is permitted, a horizontal loop can be excavated to minimize installation costs. The horizontal loop is typically 6 ft under the ground and at a loop length of 300 ft. per ton of heating/cooling. |
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Vertical Loop: Vertical loops are useful when space is a premium, such as in an urban centre. They are typically drilled at 250 ft per ton. |
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Open Loop: Where an abundance of well water can be found at a relatively consistent temperature, an open loop becomes a viable option. Water is used from the well and put back in another location. |
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Pond Loop: A pond loop is applicable where the pond is close enough and deep enough to sustain the heating and cooling options of the home. |
Geothermal operation in Winter:
As winter arrives, the outside temperature drops and thus heat begins to transfer from inside the home to outside the home, thus creating a demand for heat in order for you and your guests to be comfortable in your house.
The Ground Source Side of a Geothermal System
To heat your home a Ground Source Heat Pump will absorb heat from the ground. For simplicity this example will use 50F as an average ground temperature and 10F temperature change cross the unit. Most geothermal units will pump a liquid that runs through the unit and interfaces with the ground by one of the method noted above. As the liquid is run through the unit, it crosses a heat exchanger inside the unit. This heat exchanger is typically a coil that on one side is the liquid from the ground, and on the other side is refrigerant that is used in the unit. The liquid that comes from the ground, for example, could be an ethanol mix from a closed horizontal loop. It will enter the unit at 50F from the ground and enough heat will be absorbed by the refrigerant, located on the other side of the heat exchanger, that by the time this 50F water crosses the whole of the heat exchanger it will leave at 40F. When it leaves the geothermal unit, it then passes through the ground and absorbs energy from the earth.
A good geothermal loop design will ensure that there is enough pipe in the ground so that the liquid from the ground source heat pump supplied to the ground at 40F water has enough time in the ground to absorb enough energy that when it comes back to the geothermal unit it is back up to 50F.
Geothermal inside your Home, Shop, or Business
The 10F drop in the temperature of the liquid that goes back out to the ground is caused by an absorption of energy from Freon on the other side of the heat exchanger. The Freon is then required to go through a mechanical refrigeration cycle to change the 10F rise into usable heat for your home, shop, or business. Once it is on the other side of the of the mechanical refrigeration cycle, it can transfer very usable heat.
If you are using a ducted system such as ZONEFLEX, the cool air that is return air from your home, shop, or business would be passed over a coil that is warmed by this refrigeration and rejects heat to the air (for example at 110F) thus heating the air that warms your home to the temperature you set by a thermostat (for example 72F).
If you are using a floor warming system, such as ZONEBASE, the liquid circulating in your floor would return through your circulator pump and be heated by the Freon by virtue of another heat exchanger. The typical supply water temperature seen to a floor on a well designed radiant floor warming system is anywhere between 80F (best) – 90F (standard) – 110F (ok).ned and installed geothermal system has little or no geoimpact to the area in which it is installed.
Geothermal operation in Summer:
As summer arrives, the outside temperature rises and thus heat begins to transfer from outside your home to inside your home, thus creating a demand for heat in order for you and your guests to be comfortable in your house.
The Ground Source Side of a Geothermal System
To heat your home a Ground Source Heat Pump will absorb heat from the ground. For simplicity this example will use 50F as an average ground temperature and 10F temperature change cross the unit. Most geothermal units will pump a liquid that runs through the unit and interfaces with the ground by one of the method noted above. As the liquid is run through the unit, it crosses a heat exchanger inside the unit. This heat exchanger is typically a coil that on one side is the liquid from the ground, and on the other side is refrigerant that is used in the unit. The liquid that comes from the ground, for example, could be an ethanol mix from a closed horizontal loop. It will enter the unit at 50F from the ground and enough heat will be absorbed by the liquid from the freon, located on the other side of the heat exchanger, that by the time this 50F water crosses the whole of the heat exchanger it will leave at 60F. When it leaves the geothermal unit, it then passes through the ground and rejects the heat to the cool earth.
A good geothermal loop design will ensure that there is enough pipe in the ground so that the liquid from the ground source heat pump supplied to the ground at 60F water has enough time in the ground to reject enough energy that when it comes back to the geothermal unit it is back up to 50F.
Geothermal inside your Home, Shop, or Business
The 10F rise in the temperature of the liquid that goes back out to the ground is caused by an rejection of heat from Freon on the other side of the heat exchanger. This Freon is then required to go through a mechanical refrigeration cycle to change the 10F rejected to the group into usable heat absorption to cool your home, shop, or business. Once it is on the other side of the of the mechanical refrigeration cycle, it can very efficiently cool your home.
If you are using a ducted system such as ZONEFLEX, the warm air that is return air from your home, shop, or business would be passed over a coil that is chilled by this refrigeration and rejects heat to the ground (for example the supply air to the rooms can be at 55F) thus cooling the air that cools your home to the temperature you set by a thermostat (for example 75F).