Appendix B: Installing Sensors - Grundfos Geo-Flo Universal Pump Controller Installation, Operating And Maintenance Manual

20 | Installation, Operating, and Maintenance Manual
Thermistor Installation
Install thermistors in any 1/4" NPT Female port
using a quality thread sealing compound (pipe
dope). Be sure to insulate the entire fitting/pipe/
thermistor to prevent conductive heat transfer
from affecting the thermistor reading. Adding
additional wire to the thermistor leads is accept-
able since the resistance of the thermistor is
much greater than the resistance of the additional
wiring. Figure 20 provides several examples of
thermistor to fitting assemblies.
Grundfos VFS Sensor Installation
Install the VFS sensor and flow tube by utilizing
the 1" hose barb transition fittings. Allow 6-10"
of 1" rubber hose in front of and behind the flow
tube. Be sure that there are no sharp bends/
elbows directly in front of or behind the sensor.
Verify that the arrow on the flow tube matches
the pumping direction or the sensor will not per-
form correctly. The sensor can be placed on the
entering water or leaving water side of the heat
pump. See Figure 21.

Appendix B: Installing Sensors

1" Hose Barb x
Flo-LInk double
O-ring with 1/4"
FPT Port
Figure 21: Flow Sensor Installation
1" Hose Barb x 1"
MPT Elbow with
1/4" FPT Port
Figure 20: Thermistor Installation
From Loop
1" Hose Barb x
Flo-Link double
O-ring
1" Rubber Hose
VFS 10-200 Flow
Tube with Sensor
1" Hose Barb
Adapter
To Heat Pump
Rev. 05JUL2016
1" Hose Barb x
Flo-LInk double
O-ring Elbow with
1/4" FPT Port
Hose Clamps
Hose Clamps
G1-1/4 Nut
1" Rubber Hose