solar hot water systems are probably the oldest
commercially available solar systems. At the turn
of the century there were large numbers of solar
water heating systems on roof tops, especially in
Los Angeles and Florida. Very little has changed
from the original concept. Put a water holding
tank in a box, with glass on the side facing south
and fill it with water. No moving parts, nothing
to break down, free fuel and no pollution.
The passive solar
water heater is known today by many names; PSWH,
Batch Heater and Bread Box are the most common and
then there is the very technical; Integrated
Collector and Storage System (ICS).
The PSWH of today
usually starts with a 40 gallon, glass lined tank.
These tanks come disguised as ordinary electric
water heaters, which are stripped of their
appliance shell and insulation. Painted flat
black, with high temperature engine or barbecue
paint and they're ready for solar.
collector storage systems, the solar water storage
system is built into the collector. The potable
water in the collector unit is heated by the sun
and delivered by city or well water pressure to an
auxiliary tank (which contains non-solar back-up
heating) or directly to the point of use.
A thermosiphon solar water heating system has a
tank mounted above the collector (normally on the
roof) to provide a natural gravity flow of water.
Hot water rises through piping in the collector,
which is mounted below the tank; heavier cold
water sinks to the lowest point in the system (the
collector), displacing the lighter hot water which
rises to the tank.
The ICS and thermosiphon systems are simple since
they use no pumps or controllers and water always
flows through the collector.