Grundfos Geo-Flo Universal Pump Controller Installation, Operating And Maintenance Manual page 8

6 | Installation, Operating, and Maintenance Manual
B. HP IN2: Receives a contact closure from the relay connected to Y2, closing the circuit between the left and
right terminals. This connection is not required when operating the controller in ∆T mode. Relay is a SPST
N.O. general purpose relay (equivalent to 90-360 WR/RBM Type 184).
C. 24VAC IN: Left terminal connected to "R" at heat pump; right terminal connected to "C" at heat pump.
Important Wiring Notes for Variable Speed Flow Centers:
Heat Pumps Without an Accessory Terminal
Many geothermal heat pumps have an accessory terminal (sometimes labeled "A" or "ACC"). One of the
purposes for the accessory terminal is for control of a solenoid valve for open loop systems. However,
it also a ects the operation of the Grundfos UPC-GEO variable speed pump controller. This document
will address wiring for systems without an accessory terminal.
The accessory terminal is typically connected to the output from the lockout board to the compressor
contactor coil (labeled "CC" in the example below). The compressor contactor is only energized after
the anti-short cycle delay, and if there are no lockouts. If the water solenoid is connected between "C"
IMPORTANT:
(common) and the heating/cooling thermostat terminal ("Y" or "Y1"), the solenoid will be energized
Controller must
any time there is a thermostat call. Most of the time, this approach works ne. However, if the heat
be grounded.
pump is locked out, the water will continue to run even when the compressor is locked out, potentially
causing substantial use of water and electricity for the pump. Therefore, using the "CC" connection to
engage an accessory ensures that the solenoid valve will not open if the unit is locked out.
NOTE: This only applies to solenoid valves without an end switch. Solenoid valves with an end switch
must be wired to the thermostat heating/cooling terminals.
A similar issue could occur with the variable speed pump controller. If the heat pump is locked out, and
the controller is in temperature di erence (∆T) mode, the thermostat will continue to call, but there will
be no ∆T because the compressor is o . Once the heat pump is reset, the controller may not be able to
react qucikly enough, potentially causing insu cient water ow. When an accessory terminal is used,
the control will only be enabled when the compressor contactor is energized.
If the heat pump being installed/serviced does not have an accessory terminal, the example diagram
below provides suggestions for simulating an accessory terminal.
Figure 2b: Wiring Diagram for heat pumps requiring an additional isolation relay -- see Notes A & B, above
Typical WSHP Lockout Board Without an Accessory Terminal
TEST
NO
YES
STATUS
Find an easy
to access
Common (C)
connection*
Figure 2c: Wiring Diagram for heat pumps with an external compressor contactor, but without an accessory
relay -- see Note A, previous page
EWT
LWT OUT IN REF
HP IN1 HP IN2
PWM
BRN BLK BLU
(Note B)
Y2
(Note A)
ACC C
LP1 LP2 Y FLOW HP1
SWITCH
C FAULT R
Fault
Contactor
Coil
24 VAC
230 VAC
*May require a "piggyback" spade connector.
EWT LWT C + -
THERMS
1-10 DCIN
(Note C)
T-STAT
C
HP2
CC
CC
Compressor
Contactor
Use for ACC
Coil
connection*
208-230 VAC Input/Output
Power to UPS26-99 (2nd pump)
for two pump flow centers. Do
not connect Magna GEO single
pump flow center to this
terminal block.
L1 L2 N1 N2
24VAC INGND
OUT IN OUT IN
AUXILIARY
R C
UPS26-99 (2nd pump)
Do not connect to
Magna GEO pump.
NOTES:
D. Connect CC and C to isolation
relay # 1 (shown as ACC and C
in Figure 2b).
E. Connect Y2 and C to isolation
relay #2 (shown as Y2 and C in
Figure 2b).
Rev. 05JUL2016
115V
or 230V
pump