Heat Controller HTV Series Installation, Operation & Maintenance Instructions Manual page 16

GROUND-LOOP HEAT PUMP APPLICATIONS
3. Try to maintain a uid level in the tank
above the return tee so that air cannot
be continuously mixed back into the
uid. Surges of 50 psi can be used to
help purge air pockets by simply
shutting o the return valve going into
the ush cart reservoir. This "dead
heads" the pump to 50 psi to purge,
dead head the pump until maximum
pumping pressure is reached. Open
the return valve and a pressure surge
will be sent through the loop to help
purge air pockets from the piping
system.
4. Notice the drop in uid level in the ush
cart tank when the return valve is shut
o . If air is adequately purged from the
system, the level will drop only 1-2
inches in a 10" diameter PVC ush tank
(about a half gallon), since liquids are
incompressible. If the level drops more
than this, ushing should continue since
air is still being compressed in the loop
uid. Perform the "dead head"
procedure a number or times.
Note: This uid level drop is your only
indication of air in the loop.
Antifreeze may be added before, during or
after the ushing procedure. However,
depending upon which time is chosen,
antifreeze could be wasted when emptying
the ush cart tank. See antifreeze section
for more details.
Loop static pressure will uctuate with the
seasons. Pressures will be higher in the
winter months than during the cooling
season. This uctuation is normal and
should be considered when charging the
system initially.
HTV/HTD/HTH SERIES
Run the unit in either heating or cooling for a
number of minutes to condition the loop to a
homogenous temperature. This is a good
time for tool cleanup, piping insulation, etc.
Then, perform nal ush and pressurize the
loop to a static pressure of 50-75 psi (winter)
or 35-40 psi (summer). After
pressurization, be sure to loosen the plug at
the end of the Grundfos loop pump motor(s)
to allow trapped air to be discharged and to
insure the motor housing has been ooded.
This is not required for Taco circulators.
Insure that the Flow Controller provides
adequate ow through the unit by checking
pressure drop across the heat exchanger
and compare to the pressure drop tables at
the back of the manual.
ANTIFREEZE
In areas where minimum entering loop
temperatures drop below 40°F or where
piping will be routed through areas subject
to freezing, antifreeze is required. Alcohols
and glycols are commonly used as
antifreeze. Check with local authorities for
the antifreeze best suited to your area.
Freeze protection should be maintained to
15°F below the lowest expected entering
loop temperature. For example, if 30°F is
the minimum expected entering loop
temperature, the leaving loop temperature
would be 25 to 22°F and freeze protection
should be at 15°F. Calculation is as
follows:
12
15
30°F - 15°F = 15°F
Heat Controller, Inc.