Zehnder Rittling VS Series Installation, Operation And Maintenance Manual page 20

Ground water
applications
18
Flow regulation
The preferred method of control
requires a flow control device
mounted on the outlet of the
water control valve. The device
is typically a brass fitting with
an orifice of rubber or plastic
material that is designed to allow
a specified flow rate. On occasion,
flow control devices may produce
velocity noise that can be reduced
by applying some back pressure
from the ball valve located on the
discharge line. Slightly closing
the valve will spread the pressure
drop over both devices, lessening
the velocity noise.
Water coil low temperature limit
setting
Zehnder Rittling's heat pump
controller includes a user
configurable switch (DIP switch 2
on the PCB controller) to change
the low water temperature cutout
(FP1) setting between water
(30 °F) and Glycol (10 °F). When
loop conditions allow (antifreeze is
used), the FP1 DIP switch should
be set to the Glycol (10 °F) setting
to avoid nuisance faults.
Table 4: Water limit
guidelines
Min. flow
EWT Min. Antifreeze
rate
(°F) required?
(GPM/ton)
50 1.5
40-50 3
40-50 1.5
20-40 3
No
No
Yes
Yes