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 FIGURE 2-28
Balancing Valves
and Thermometers
Installed On a
Collector Array
The best choice for this application is a spring-loaded check valve. Make sure the
seat and seals are appropriate for the fluid being used. (Figure 2-29)
It is also worth noting that tests of large numbers of check valves have found wide
variations in opening pressures and high overall failure rates. For this reason, it is
important to inspect check valves for proper operation at every system inspection,
as explained in the inspection chapter, Section 3.1.3.
Pressure Relief Valves
These valves (sometimes called PRV's) are used only in the collector loop of
closed-loop systems. Since they only respond to pressure changes, they should not
be used on pressurized water (city water) lines or tanks. A strong internal spring
keeps the valve closed until the system pressure exceeds some preset limit.
(Figure 2-30)
FIGURE 2-29
Swing (left) and
Spring (right) Check
Valves
The outlet port of pressure relief valves is piped downward to within 10 in. of the
floor, to protect anyone who happens to be nearby, and to minimize damage to
electrical and other components, should the valve open.
OPERATION
2.7 COMPONENT OPERATION
35
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