Re: Introduction to Eric Hart
From: Roger Diggle (
Date: Sat, 12 Nov 94 11:48 CST
On 11/12/94 Eric Hart wrote:

> As an example, I know an architect (through the Riverside group) who
> has designed an air to air heat exchanger that is very cheap and
> effective.  He has used this design on a solar greenhouse he
> designed in SE Minnesota and it works great.  It essentially uses
> the earth as a means to moderate the air temperature.  Air is pulled
> out of the house and funneled into a plastic pipe which has another
> porous pipe running inside it.  These pipes are underground so stay
> at a constant temperature.  The inside air is pushed out the larger
> pipe while the smaller pipe pulls in outside air.  The two air
> masses mix inside the pipe and what comes back into the house is air
> that is humidified/dehumidified and heated/cooled (depending upon
> the time of the year).  At this solar greenhouse, such an exchanger
> lowered the outside air being pulled in by 10 degrees F (82 to 72
> degrees).  This is just the basic idea, don't try designing a system
> on these instructions.

This sounds to me not like air to air heat exchange, but air to earth heat
exchange, as it's described here.  that could be useful, too, but it isn't
the same thing, won't necessarily accomplish the same purpose.  You say that
the inside pipe is porous, and that the airstreams mix.  That sounds
counterproductive in getting rid of indoor pollutants.  But I may have
entirely the wrong picture of the device... I'd enjoy seeing a more detailed
description.  Also, please zap me with your two-page synopsis of alternative
construction practices.

Roger Diggle       diggle [at]

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  • Introduction to Eric Hart Fred H Olson WB0YQM, November 12 1994
    • Re: Introduction to Eric Hart Roger Diggle, November 12 1994

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