Re: "Makeup" or return air.
Regardless of what they are called the units use an air to air heat exchanger which transfers heat from the hot air to the cool air regardless of the direction. Add a blower and a proper filtration system and you get the fancy name. And by the way a central vacuum system, unless the vacuum unit is mounted outside of the house, causes a zero loss of air in the structure.
Last edited by JLMCDANIEL; 07-15-2008 at 02:50 PM.
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