Whenever an expansion tank is installed in a loop with a pump, it must
be on the suction side of the pump. Installation of an expansion tank
on the discharge side of the pump can result in pump cavitation and
Automatic (float type) air vents are probably the most incorrectly applied component
in solar systems. (Figure 5-14) One difficulty is that no American manufacturer of
automatic air vents will advocate their use outside. Another problem is
incompatibility with solar fluids. Finally, very few automatic air vents are capable of
withstanding the pressures they are exposed to in solar applications.
An Automatic Air
Automatic air vents can be used only in piping loops containing water. When used
with solar fluids, an automatic air vent will eventually vent enough fluid vapor or leak
enough to render the system inoperative. In many cases, the vent seals are not
compatible with the fluid or the pressure. The end result is a stained roof and an
inoperative, sometimes damaged, solar system.
5.2 REPAIR PROCEDURES