| This is a major
feature of the drain back system illustrated in
Figure 4. Freeze protection is provided when the
system is in the drain mode. Water in the
collectors and exposed piping drains into the
insulated drain-back reservoir tank each time the
pump shuts off. A slight tilt of the collectors is
required in order to allow complete drainage. A
sight glass attached to the drain-back reservoir
tank shows when the reservoir tank is full and the
collector has been drained.
Figure 4
In this particular
system, distilled water is recommended to be used
as the collector loop fluid- transfer solution.
Using distilled water increases the heat transfer
characteristics and prevents possible mineral
buildup of the transfer solution.
When the sun shines again, the pump is activated
by a differential controller. Water is pumped from
the reservoir to the collectors, allowing heat to
be collected. The water stored in the reservoir
tank circulates in a closed loop through the
collectors and a heat exchanger at the bottom of
the solar tank.
The heat exchanger transfers heat from the
collector loop fluid to the potable water in the
solar tank. |
Saturday July 05, 2008 - 12:43 PM
