11
Flow Controller 3
R e v. : F e b u r a r y 9 , 2 0 1 6
Figure 10b: Valve Position B - Unit Fill
Unit
Garden
Hose
Flow
Controller
Loop
Valve
Position
Flush Cart
Flushing the Earth Loop
Front of F
.C.
Valve Position
Figure 10c: Valve Position C - Loop Flush
Unit
Garden
Hose
Flow
Controller
Loop
Valve
Position
Dead Head
Pump Test for
Air
Flush Cart
Front of F
.C.
Valve Position
This position should be switched while filling to fill the
unit heat exchanger and hose kit. The position should be
maintained until water consistently is returned into the flush
reservoir.
Switch to valve position C. The supply water may be shut off
and the flush cart turned on to begin flushing. Once the flush
reservoir is full, do not allow the water level in the flush cart
tank to drop below the pump inlet line or air can be pumped
back out to the earth loop. Try to maintain a fluid level in the
tank above the return tee so that air can not be continuously
mixed back into the fluid. Surges of 50 psi [345 kPa] can
be used to help purge air pockets by simply shutting off the
return valve going into the flush cart reservoir. This process
‘dead heads’ the pump to 50 psi [345 kPa]. To dead head
the pump until maximum pumping pressure is reached,
open the valve back up and a pressure surge will be sent
through the loop to help purge air pockets from the piping
system. Notice the drop in fluid level in the flush cart tank.
If all air is purged from the system, the level will drop only
1 - 2 inches [2.5 - 5 cm] in a 10” [25.4 cm] diameter PVC
flush tank (about a half gallon [1.9 liters]) since liquids are
incompressible. If the level drops more than this level,
flushing should continue since air is still being compressed
in the loop fluid. Do this a number of times. When the fluid
level is dropping less than 1-2” [2.5 - 5 cm] in a 10” [25.4 cm]
diameter tank, the flow can be reversed.
NOTICE: Actual flushing time require will vary for each
installation due to piping length, configuration, and flush cart
pump capacity. Most closed loop installations will require at
least 20 minutes or longer.
