| Criterion
6.3.9 Entrapped Air
Criterion
text:
Suitable
means for air or gas removal from all high points in the piping
system and any other location where air is most likely to accumulate
shall be provided. The method of removal shall be appropriate
for the system type as follows:
Automatic for open loop (direct) circulating systems using potable
water as the heat transfer fluid.
Manual or automatic for closed loop (indirect) systems.
Not required for integral collector storage (ICS) and open loop
thermosiphon systems.
Comments:
Installers must follow the instructions provided in the
manufacturer's SRCC approved installation manual. The manual will
describe the types of components and installation methods required
to meet this criteria.
Figure
1 through 3 show examples of various automatic air vents. The
air vent in Figure 3 is a combination air vent and vacuum breaker.
Figure
1
Figure 2
Figure 3
Special
care must be taken to properly install air vents. They should
be installed at all high points of the system. The air vent must
be installed in a true vertical position to function properly.
Follow the manufacturer's installation manual instruction in regard
to the final setting of the dust cap mechanism. In most direct
systems, the cap is loosened one quarter turn, while in closed
systems, the cap is tightened after having expelled all the air
during the collector loop pressurizing procedure. If in doubt,
refer to the manufacturer's SRCC approved installation manual.
The
air vent in Figure 4 has not been installed in a true vertical
position, but instead in the plane of the solar collector. This
is not the proper installation method.
Figure 4
The
air vent in Figure 5 has been installed correctly. Note that it
is pointing in a true vertical position. This prevents any jamming
of the air vent's internal components. (See Figure 2)
Figure 5
Air
vents should also be installed in locations in the piping where
air traps may occur, as illustrated in Figure 6.
Figure 6
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