Wiring (One Flow Center/Two Heat Pumps) - Grundfos Geo-Flo Universal Pump Controller Installation, Operating And Maintenance Manual

8 | Installation, Operating, and Maintenance Manual
Wiring the Controller (One Flow Center / Two Heat Pumps)
WARNING: OPEN THE POWER SUPPLY DISCONNECT SWITCH AND SECURE IT IN AN OPEN
POSITION PRIOR TO PERFORMING ELECTRICAL WORK. VERIFY THAT POWER HAS BEEN
DISCONNECTED PRIOR TO WIRING THE CONTROLLER. FAILING TO SECURE THE ELECTRI-
CAL SUPPLY COULD RESULT IN SERIOUS INJURY OR DEATH. THIS EQUIPMENT SHOULD BE
INSTALLED AND SERVICED BY QUALIFIED PERSONNEL ONLY.
NOTE: The Magna GEO 32-140 motor requires no external protection. Wiring the Magna GEO directly to mains
power is recommended. See Appendix C for more information.
ACC R R
HP IN1 HP IN2
Heat Pump
Terminals ACC C
HP-1
Figure 3: Wiring Diagram for connecting two heat pumps to one
variable speed flow center. See figures 4a and 4b for piping.
NOTES:
A. Above wiring should be used with a flow sensor to avoid potential nuisance trips if one unit is in cooling
and one is in heating or other temperature difference conditions (e.g. long runs of piping in the mechanical
room, settling to room temp.).
B. Set stage one flow between minimum and nominal full load flow rate of the larger unit. Set stage two flow
between minimum and nominal flow for both units on full load. For example:
• 4 ton and 3 ton heat pump
• Minimum full load flow rates are 9 GPM (4 ton) and 7.5 GPM (3 ton); nominal flow rates are 12 GPM
(4 ton) and 9 GPM (3 ton).
• Stage one flow rate should be 9 to 12 GPM (between min. and nom. for 4 ton).
• Stage two flow rate should be 16.5 to 21 GPM (between min. and nom. for both heat pumps).
• A good compromise for this example would be 10 GPM on stage 1 and 19 GPM on stage 1.
C. A zone valve is required at each unit to allow flow only through the heat pump running.
Y2 Connections for panel mount
flow center or NPV kit
Connections to UPC GEO controller
(if not using panel mount or kit)
Heat Pump
ACC C Terminals
HP-2
ACC is accessory terminal (energized when
compressor contactor coil is energized). If
heat pump does not have an accessory
terminal, consult Figures 2c and 2d.
Rev. 05JUL2016