ART TEC
Guy Marsden

SOLAR HEATING SYSTEM CONSTRUCTION LOG

PROGRESS REPORT:
September 23, 2002: Added Differential Temperature Controller
UPDATED March 2008

After observing my system for the first year I noticed
that the tank temperature would drop considerably between
late afternoon and mid morning.  I finally realized that
as the sun went down the collectors became cooler
than the tank temperature, and the hot water was
being radiated out through the collectors (via the
heat exchanger) as there was still enough sun to
run the PV powered circulation pumps.

What I needed was a controller that would shut off the
pump that circulates heated water through the heat exchanger
and into the tank when the collector temperature
drops below the temperature at the top of the tank.

This type of Differential Temperature Controller
is available only as an AC powered version for over $160.00,
there was no DC powered controller that I could find. 
Being an inventor and electronics
engineer, I decided to make my own from spare parts.
Here it is:

UPDATE!  March 2008
I have formed ART TEC Solar to manufacture my
Solar Differential Temperature Controller,
click the images below to order one.
 

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