Williams AH Installation, Operating, & Maintenance Instructions page 9

FIGURE 7
FIGURE 8
Purging and Cleaning ONDemand
water pressure should also be used to purge the
ONDemand loops instead of the pressure created by
the ONDemand circulators. Primary pump(s) should
be OFF, V-2 and V-3 closed and main fill valve V-1
should be open to maintain city water pressure in
the clean primary loop.
FIGURE 8
To purge ONDemand loop, open supply valve to the
terminal unit V-4 and close return valve V-5. Opening
the manual air vent / purge valve will allow city water
Loop(s) City
®
pressure to purge air from the entire supply pipe,
Load-Match circulator and terminal unit.
To purge the return side, close V-4 and open V-5 and
open the manual air vent / purge valve until no more
air is released. Both valves V-4 and V-5 can then be
opened for normal operation.
If the ONDemand loop has a significant number of
fittings, multiple changes in elevation or is longer than
normal (i.e. 30 ft.), additional air vents should be located
at the high points to eliminate isolated air pockets.
WILLIAMS AIR HANDLER MODELS AH / AV 9