2 | Installation, Operating, and Maintenance Manual
Rev. 05JUL2016
ΔT based control (Two immersion thermistors required)
The UPC-GEO receives a 24VAC signal from the heat pump or thermostat for heating or cooling. The UPC-GEO
then provides a PWM signal to the Magna GEO 32-140 pump (or 0-10 VDC output for other pumps) and moni-
tors the temperatures provided from the EWT and LWT thermistors and the return signal from the pump. The
UPC-GEO drives the pump at 90% for two minutes before increasing or decreasing the pump speed based on
the delta-T (ΔT) set point for heating or cooling mode and the actual ΔT of the system. The controller recog-
nizes whether the heat pump is in heating or cooling mode by monitoring the EWT and LWT temperatures (i.e.
heating mode: LWT<EWT; cooling mode: LWT>EWT). For higher flow rate and/or head loss systems a two-pump
variable speed flow center system may be required. This flow center consists of a single variable speed Magna
GEO 32-140 and a constant speed UPS26-99. The UPC-GEO attempts to satisfy the ΔT requirement by first using
the more efficient Magna GEO 32-140 pump. If the Magna GEO reaches its maximum performance level before
satisfying the ΔT set point requirement, the UPC-GEO energizes the UPS26-99 and ramps the Magna GEO down
to match the requirement thereby minimizing pumping power.
Technical Specifications
Parameter
Rating
Tolerance (+/-)
Input Voltage
24 VAC, 200 mA Max
10%
Input Frequency
60 Hz
20%
PWM Input Frequency
75 Hz
10%
PWM Input Voltage
Open Collector
n/a
PWM Output Frequency
3.9 kHz
10%
PWM Output Voltage*
12 VDC
10%
0-10 VDC Output Voltage*
1 to 10 VDC
10%
Thermistor Input
NTC 10k
N/A
HP IN1
24 VAC or dry contact across terminals 10% (for 24 VAC Input)
HP IN2
24 VAC or dry contact across terminals 10% (for 24 VAC Input)
1-10 VDC input
Not currently used
N/A
GND
Earth Ground Connection
N/A
L1/N1 (input for second pump)
120/208-230 VAC
10%
L2/N2 (output for second pump)
120/208-230 VAC
10%
Relay for L1/N1 to L2/N2
4A Max
N/A
Display
128 x 64 pixels
N/A
DB9 connector (serial communication) N/A
Nominal power consumption
3.5 VA
N/A
*Default controller output is PWM. Alternate 0-10 VDC output may be selected in the controller menu for Flow
mode or ∆T mode.
