Non-solar loops you may be familiar with are hydronic heating baseboard loops.
This would be considered a closed loop. Except for small amounts of make-up
water, the fluid in the loop never changes, and is rarely exposed to air.
A recirculating DHW system is an example of an open loop. The water changes on
a regular basis, with fresh city water coming in whenever a fixture is opened. This
fresh water brings in fresh oxygen. At the same time, the exiting water is exposed
to air (Figure 2-2).
A Recirculating DHW
2.1.2 Common Components. Almost all active, liquid, solar heating systems
include certain components. These are:
o Solar collectors
o Circulation pumps and piping
o Controls and sensors
o Some method of freeze protection
A simplified solar heating system is shown in Figure 2-3. Heat energy from the sun
enters, and is trapped by, the solar collectors. These are usually mounted on the
roof, or near the building.
2.1 BASIC SYSTEM CONFIGURATION