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Old 10-06-2008, 09:03 PM
 
Location: hopefully NYC one day :D
411 posts, read 1,163,379 times
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You know how when you cool a room, the unwanted heat is placed outside? Well is there any way to harvest that heat and use it for energy? Do green buildings, zero energy buildings, or solar panels do this? If nothing can be done about this, does this mean a dense urban center would always be hotter (even without the urban heat island effect) than the suburbs because of more heat displaced in the already hot air?
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Old 10-06-2008, 09:26 PM
 
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Heat from ACs can be used to heat water. The problem is that the systems only help during hot weather and failure of a line can mean water infiltration and destruction of the AC system.

Moving heat isn't adding sensible heat to the environment, the inefficiencies of the motors and compressors make the energy used in the process convert to heat.

Larger cooling units resort to evaporation for more efficient transfers of heat. That is why you may see wisps of steam coming out of cooling towers under certain weather conditions. The air is hotter, but the evaporated water makes it a lot cooler and more humid than it would otherwise be. In a sense, this mimics the transpiration of trees.
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Old 10-06-2008, 10:15 PM
 
Location: hopefully NYC one day :D
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^^what is the air hot from?

Does the steam pollute the air?
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Old 10-07-2008, 08:43 AM
 
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The heat that was moved from the interior of the building to the exterior comes from different sources. Heat absorbed from solar heating, body heat, copy machines, computers, lights, etc.. All the air handler does is transport that heat. Does steam pollute the air? If you call water vapor a pollutant, the I guess so, in the same way that trees and grasses do. The water that goes to chillers is usually pretty clean, either municipal water or well water. In that sense, watering a lawn pollutes. Same idea, different temperature.
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Old 10-07-2008, 09:41 AM
 
Location: North Pole Alaska
886 posts, read 5,705,184 times
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I know this is not necessarly what you were talking about but I just installed a heat pump in my house and it is great. In the summer it takes heat out of the house and in the winter it brings it in. I saved $38 of last years ac bill in one month.
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Old 10-07-2008, 01:00 PM
 
Location: Brevard, NC
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With a geothermal heat pump, the heat removed when the house is cooled can be used to supply hot water. Of course this only works in the summer.
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Old 10-07-2008, 03:08 PM
 
Location: hopefully NYC one day :D
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Can highrises have heat pumps?
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Old 10-07-2008, 07:58 PM
 
Location: hopefully NYC one day :D
411 posts, read 1,163,379 times
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does heat being displaced into the hot air outside even increase the outdoor temperature? Even if there were no urban heat island effect, would dense urban areas still be hotter than suburbs because of a greater amount of displaced heat. So do geothermal heat pumps basically harvest that heat and prevent the unwanted heat from going outside?
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Old 10-07-2008, 08:00 PM
 
Location: hopefully NYC one day :D
411 posts, read 1,163,379 times
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Quote:
Originally Posted by harry chickpea View Post
failure of a line can mean water infiltration and destruction of the AC system.
What do you mean?

************************************************
does heat being displaced into the hot air outside even increase the outdoor temperature? Even if there were no urban heat island effect, would dense urban areas still be hotter than suburbs because of a greater amount of displaced heat. So do geothermal heat pumps basically harvest that heat and prevent the unwanted heat from going outside?
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Old 10-08-2008, 09:41 AM
 
23,563 posts, read 70,158,065 times
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Last post in the thread for me. - Compressor pumps and scrolls work by compressing the working fluid - freon gas into freon liquid. Insert non-compressable water into those areas and it breaks the piston rod when the motor tries to compress the gas.

Heat being displaced is simply being moved. No more, no less. If the original heat comes from solar gain, then the outside temp change would essentially be nil, compared to if the building wasn't there. If the original heat comes from bodies and copy machines and lights, the temp charge is the heat released by those. Geothermal uses the flywheel effect of the earth to heat or cool the ground rather than the air. Eventually, some of that can reach ground surface, but if the heat is extracted from the ground in winter, then it is merely stored and released.
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