6 | Installation, Operating, and Maintenance Manual
Rev. 05JUL2016
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.
24
VAC
Input
to
P
owe
r
Cont
roll
er
(N
ote
3
)
24VAC
Input
Signal
(N
ote
2)
24VAC
Input
Signal
(N
ote
1)
Ma
gna
GEO
P
um
p
Input
/Output
Grundfos
D
irec
t
Se
nsor
Inpu
ts
1-
10
VD
C
Input
(not
us
ed
)
Ea
rt
h
Ground
Thermistor
Inputs
Y2
Brown
Bl
ac
k
Bl
ue
Entering
W
at
er
Therm
(f
rom
loop
)
Leaving
W
at
er
T
he
rm
(to
loop
)
Thermistors
Common
4-
pi
n
conn
ector
from
Grundfos
Flo
w
S
en
so
r
on
e
ith
er
Entering
O
R
Leaving
W
at
er
s
id
e
R C
LWT
EWT
OUT IN REF
PWM
HP IN1 HP IN2
LWT
EWT
C
THERMS
+
-
1-10 DCIN
24VAC INGND
AUXILIARY
L1
L2
N1 N2
OUT
OUT IN
IN
BRN BLK BLU
(Note A)
C
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.
Line V
oltage W
iring
(115V or 230V
)
UPS26-99 (2nd pump)
Do not connect to
Magna GEO pump.
115V
or 230V
pump
(Note B)
(Note C)
C
ACC
Figure 2b: Wiring Diagram for heat pumps requiring an additional isolation relay -- see Notes A & B, above
Figure 2c: Wiring Diagram for heat pumps with an external compressor contactor, but without an accessory
relay -- see Note A, previous page
LP1
HP2
HP1
Y
LP2
FLOW
SWITCH
LPS
HPS
FLOW
T-STAT
NO
STATUS
TEST
YES
C
R
CC
FAULT
Fault
Contactor
Coil
CC
Compressor
Contactor
Coil
24 VAC
230 VAC
Use for ACC
connection*
Find an easy
to access
Common (C)
connection*
*May require a “piggyback” spade connector.
Typical WSHP Lockout Board Without an Accessory Terminal
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 affects 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”
(common) and the heating/cooling thermostat terminal (”Y” or “Y1”), the solenoid will be energized
any time there is a thermostat call. Most of the time, this approach works fine. However, if the heat
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 difference (∆T) mode, the thermostat will continue to call, but there will
be no ∆T because the compressor is off. Once the heat pump is reset, the controller may not be able to
react qucikly enough, potentially causing insufficient water flow. 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.
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).
IMPORTANT:
Controller must
be grounded.
