Since the mid-1970's, tens of thousands of homes
and businesses in Canada, Europe and the U.S. have been heated and cooled by a
system that bridges the gap between high technology and energy savings-the
Geothermal Heat Pump.
Consumers are searching for a better way to get
more out of their energy dollar. Many have found the answer to be the geothermal
heat pump.
The buried pipe or ground loop, is the most recent
technical advancement in heat pump technology. The idea to bury pipe in the
ground to gather heat energy began in the 1940's, but it's only been in the last
few years that new heat pump designs and improved pipe materials have been
combined to make geothermal heat pumps the most efficient heating and cooling
systems available.
What is a Geothermal Heat Pump?
A geothermal heat pump is an electrically
powered device that uses the natural heat storage ability of the earth and/or
the earth's groundwater to heat and cool your home.
How does it work?
Like any type of heat pump, it simply moves heat energy
from one place to another, using the same scientific principle as your
refrigerator. By using the refrigeration process, geothermal heat pumps remove
heat energy stored in the earth or groundwater and transfer it to your home.
How is heat transferred between the earth
and the home
The earth has the ability to absorb and store
heat energy. To use that stored energy, heat is extracted from the earth through
a liquid medium (groundwater or an antifreeze solution) and is pumped to the
heat pump or exchanger, and the heat is used to heat your home. In the summer
the process is reversed and the indoor heat is extracted from your home and
transferred to the ground through the liquid.
Does it do both heating and cooling?
One of the things that make the heat pump so
versatile is it's ability to be a heating and cooling system in one. You can
change from one mode to another with the flick of a switch on your thermostat.
In the cooling mode, a geothermal heat pump takes heat from the indoors and
transfers it to the cooler earth through either groundwater or an underground
loop system.
Can a geothermal heat pump heat water for my
home?
YES...using a desuperheater, some types of
geothermal heap pumps can save you up to 50% on your water heating bill by
preheating the tank water. Some units can provide all of your hot water needs on
demand at the same high efficiencies as the heating/cooling cycles.
Do I need separate loops for heating and
cooling?
NO...the same loop works for both. All that
happens when changing from heating to cooling, or vise versa, is that the flow
of heat is reversed.
What types of loops are available?
There are two main types of loops available,
open and closed.
Closed Loop Systems
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The term "closed loop" is used to describe a
geothermal heat pump system that uses a continuous loop of buried plastic
pipe as a heat exchanger. The pipe is connected to the indoor heat pump to form
a sealed, underground loop through which an antifreeze solution is circulated in
a pressurized pipe.
Where can the loop be located?
Most closed loop systems are trenched
horizontally or drilled vertically in your yard-depending on land availability
and terrain.
How long and deep will the horizontal
trenches be?
Trenches are normally 4-6 feet deep and up to 400 feet long, depending
on how many pipes are in a trench. Approximately 500-600 feet of pipe are
required per ton of system capacity, which is determined by the size of the
home.
What if there isn't enough room, or it is
too rocky for a horizontal loop?
Closed-loop systems are then drilled
vertically, U-shaped loops of pipe are inserted in the drilled holes and filled
with a sealing material. About 125-150 feet of vertical holes are drilled per
ton of heat pump capacity.
How long will the loop pipe last?
Closed-loop systems are installed using special
pipe which is inert to chemicals normally found in soil and has good heat
conducting properties. Properly installed pipes will last 50-75 years. Under no
circumstances should PVC pipe be used.
How are the sections of the loop pipe
joined?
The only acceptable method to connect the pipe
sections is by thermal fusion - the connections are heated and fused together to
form a strong joint. Mechanical joining of the pipe is not an accepted practice,
and could result in loop failure due to leaks. Non-professional installations
may result in less than optimum system performance.
Open Loop Systems
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An "open-loop" system is used to describe a
geothermal heat pump system that uses groundwater from a well as a heat source.
The groundwater, which has a relatively constant year round temperature, is
pumped into the heat pump unit where heat is extracted and then the water is
disposed of in an appropriate manner.
What do you do with the discharge water?
The open discharge method simply returns the
water into a pond, ditch or drainage tile that has the capacity to accept the
amount of water used by the heat pump. Another means of discharge is into a
return well that returns the water to the ground aquifer. This second well must
have enough capacity to dispose of the water passing through the heat pump.
How much groundwater does an open-loop
system need?
This depends on the size of the unit and
manufacture's specifications, generally the average system will use about 6-10
gallons of water per minute while operating.
Does an open-loop system cause environmental
damage?
NO...they are pollution free. The heat pump
just removes heat from or adds heat to the water. There are no pollutants added
at all, the only change in the water is a slight increase or decrease in
temperature.
Major Benefits of Geothermal
Heat Pumps
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How efficient is a geothermal heat pump?
Geothermal heating systems are more the three
times as efficient as the most efficient fossil fuel furnace. Instead of burning
a combustible fuel to make heat, they simply move heat that already exists. By
doing that, they provide three units of energy for every one unit used to power
the heat pump system.
How much does a geothermal heap pump system
cost?
A system for a typical home will cost more than
if you bought a separate furnace and central air conditioning system. To get an
accurate comparison of costs you need to consider the following:
