Heating And Cooling With Geothermal Heat Pumps
Author: Christiane Perrin
The term geothermal literally means Earth/Ground (Geo) Heat (thermal).
Geothermal, or ground source heat pumps, take advantage of the constant
ground or groundwater temperatures. These heat pumps use geothermal energy
to heat and/or cool your home.
A refrigerant loop with a compressor extracts heat from one side (the ground)
and pumps it to the heating loop in your home. It is essentially the same
process that happens in your refrigerator: heat is extracted via a compressor
and refrigerant loop from the inside of your refrigerator/freezer and rejected
into your house.
In the summer the geothermal heat pump reverses its cycle, if you have an
air-conditioning system, and heat from the home is rejected into the ground
or ground water.
What makes geothermal heat pumps such a good choice for residential heating
and cooling is that they do not depend on outside air temperatures. These
heat pumps will heat your home as efficiently on a windy, zero-degree winter
day as on a 40-degree day. Provided of course, that your house is well insulated
and tight.
Geothermal heat pumps are also a very efficient way for heating and cooling
your home. They use 25-50% less energy than conventional heating and cooling
systems (Source: US DOE).
Residential applications of geothermal energy systems use water-to-water
or water-to-air heat pumps.
Water-to-Water Geothermal Heat Pumps
Water-to-water geothermal heat pumps are generally used for heating only.
They replace the gas or oil furnace that you might currently have to heat
your home and water with.
It is important to know that heat pumps work most effectively when the temperature
difference between the heat source (ground) and heat sink (floor heat or
radiators) is small.
Ground temperatures range anywhere from 50 to 75 degF, depending on where
you live. This means that geothermal heat pumps are generally not suitable
for standard hot water baseboard applications, which are designed for heating
water temperatures of 180 degF. Floor heat and low-temperature radiators
require water temperatures in the range of 95 to 140 degF.
Some newer heat pump models are now equipped with so-called desuperheaters
that can transfer excess heat from the geothermal heat pump compressor to
the domestic water heater. Your geothermal heat pump can also effectively
and quickly heat water for your bathtub, shower and sinks.
Water-To-Air Geothermal Heat Pumps
These types of ground source heat pumps are generally used when you need
air conditioning. The Water is the heat sink, where you reject the heat
from the house. The Air is the air that is distributed through your home
via ductwork.
Otherwise, these heat pumps function the same way as water-to-water heat
pumps. And again, the efficiency of a geothermal heating and cooling system
is far better than that of a traditional system.
Important To Know
The first step towards making a geothermal heat pump system be a reliable
and efficient heating (and cooling) system for your home is to minimize
the heating and cooling requirements with a well-insulated building envelope
and strategically placed windows for passive solar gain.
Not only is your first cost reduced, because your system will be smaller.
You will also tremendously increase the comfort of your home.
Geothermal heat pump systems are best designed and installed by professionals.
It is not recommended to DIY. These systems must meet specific requirements.
Especially the piping laid out in the ground, or down to the ground water
table, must be designed and installed correctly to ensure that your geothermal
heat pump system works as intended.
About the Author:
Christiane Perrin is a registered professional HVAC engineer with a passion
for the environment. She is excited about the building industry going green
and wants to support homeowners on their journey to building and remodeling
green homes. http://www.greenandsustainablebuildings.com