Diagram GeoThermal Heating and Cooling
There's nothing like a diagram geothermal heating and cooling to help one understand how these systems work.
According to the Geothermal Heat Pump Consortium, "Geoexchange is an increasingly popular choice for homes, but it's as old as the earth itself. By tapping into the relatively constant temperature of the earth below the frost line, geoexchange heats and cools your home at significant savings."
Diagram Geothermal Heating in Winter
Geoexchange Systems—Outstanding home comfortthrough advanced technology
How would you like to have aheating and air conditioning systemin your home that can:
Sound too good to be true?
In fact, such units, calledgeoexchange systems, (see diagram geothermal heating and cooling) offer such alengthy list of benefits that at firstglance they do seem too good to betrue.
Their benefits, though, flow directlyfrom the clever application ofsound technology—what you canthink of as good science.Once you understand howgeoexchange systems work, (see diagram geothermal heating and cooling) you’llunderstand how they can bring suchan attractive list of benefits to yourhome.
What They DoGeoexchange systems (see diagram geothermal heating and cooling) provide heat inthe winter and cooling in the summer,at efficiencies that are far better thanthose for most alternative systems.Like conventional heat pumps, theyare essentially air conditioners thatcan also run in reverse to provide heatin the winter. The primary differenceis that they rely on the nearly constanttemperature of the earth for heattransfer instead of the widely fluctuatingtemperatures of the outside air.That is the key to the geoexchangeunit’s surprising efficiency. See diagram geothermal heating and cooling.
Diagram Geothermal Cooling in Summer
How They WorkGeoexchange systems, (see diagram geothermal heating and cooling) like commonheat pumps and air conditioners,make use of a refrigerant to helptransfer (or pump) heat into and outof your home.
The refrigerant helps the geoexchangesystem take advantage of twoprimary principles of heat transfer:
1. Heat energy always flows fromareas of higher temperature to areasof lower temperature.
2. The greater the difference intemperature between two adjacentareas, the higher the rate of heattransfer between them.Refrigerators, air conditioners, andheat pumps all operate by pumpingrefrigerant through a closed loop in away that creates two distinct temperaturezones—a cold zone and a hotzone.
The simplest example of such asystem is the universally familiarhome refrigerator. In a refrigerator, afan blows the air inside the box overtubes containing refrigerant that isvery cold (typically below 0°F). Heatflows from the interior air to the coolerrefrigerant.
The refrigerant is then pumped tothe high-temperature section, which isexposed to room air outside therefrigerator box. Because the refrigerantis hot in this zone, it gives up heatto the relatively cooler air in theroom, before flowing back to the coldzone to begin the loop again.An air conditioner works in exactlythe same way, except that it extractsheat from the air inside a room orbuilding and transfers it to the air outsidethe building.
A conventional heat pump adds areversing capability, so the hot zoneand the cold zone can be switched.With the zones reversed, it can extractheat from the outside air in the winterand transfer it inside.
Granted, being able to extract heatfrom frigid winter air seems like itshouldn’t work. But it will if we canexpose the cold air to refrigerantthat’s even colder than it is. And modernheat pumps can do that.
If the outside air gets extremelycold, though, a heat pump just can’tmake the temperature of the coldzone low enough. That’s when supplementalelectric heating elementskick in. Working much like a toaster,they supply warmth to the house, butat very high relative cost.
The Super Efficiency ofGeoexchange
Standard heat pumps, while relativelysimple to operate, face one majorchallenge. Their operating efficiencyis lowest when demand is highest;that is, heat pumps have to workhardest when we want the most fromthem.
As we’ve just seen, a regular heatpump extracts heat energy from outsideair in winter, and rejects heat tooutside air in summer. Unfortunately,the colder the outside air, the moredifficult it is to extract heat from it,and the hotter the outside air, theharder it is to transfer heat to it.
The temperature differencebetween the air and the refrigerant issmall in both cases, lowering heattransfer rates within the system.Yet, the colder it gets outside, thehigher the rate of heat loss throughwindows, around doors, and throughwalls and roofs, and the more heat weneed to pump inside to keep indoortemperatures comfortable.
In summer, we face a similardilemma. The hotter it gets outside,the higher the rate of heat infiltrationinto the house, and the more heatremoval we need to maintain comfort.
A geoexchange system (see diagram geothermal heating and cooling) eliminatesthis dilemma by using the relativelyconstant temperature of the earth as aheat source in winter and a heat sinkin summer, instead of outside air.
Throughout most of the U.S., thetemperature of the ground below thefrost line(about 3 to 5feet below thesurface)remains at anearly constanttemperature,generally in the45°–50°F rangein northern latitudes,and inthe 50°–70°Frange in thesouth.
So, in thewinter, ageoexchangeunit can extractheat fromground that’srelatively warm compared to the coldoutside air, (see diagram geothermal heating and cooling) and in the summer, it candischarge heat to ground that is relativelycool, compared to the hot outsideair. Since the difference betweenthe refrigerant temperature and theground temperature remains relativelyhigh in both seasons, so do heat transferrates.
Consequently, the geoexchangesystem operates at much higher year roundefficiencies than a standardheat pump.
The Cleanliness ofGeoexchange Systems
Installing a geoexchange system isenvironmentally responsible. Since ageoexchange system merely transfersheat from the ground into your homein winter, (see diagram geothermal heating and cooling) you don’t need to burn anyfossil fuels to create a warm interiorenvironment.
This approach drastically reducescarbon dioxide emissions (a greenhousegas) compared with the operationof other heating systems, andcompletely eliminates the heating systemas a potential source of carbonmonoxide fumes within your home—making the geoexchange system anenvironmentally friendly as well assafe and healthy alternative to traditionaloil and gas furnaces.
Now....wouldn't you like to start saving on your heating and cooling bills too? Study the diagram geothermal heating and cooling and it will help you understand this amazing system.
You'll never pay high energy bills again, summer or winter.
Thank you to Geothermal Heat Pump Consortium at GeoExchange.Org for the above diagrams and information.
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