Heat Pump Water Loop Controller


The SZ2161 is a microprocessor-based controller
designed for water source heat pump plant control


• Stand-alone or network operation • 365-day time clock with two holiday schedules, automatic leap year and daylight savings correction • No backup battery required for control parameters, schedule or clock • Supply and return condenser water temperature inputs • Supply and return loop water temperature inputs • Outdoor air temperature input • Boiler supply water temperature input • Four digital inputs for status • External time clock input • Local override and remote override capability • 12 digital outputs for control of • damper • spray pump • 2 loop pumps • 2 boiler pumps • 2 fan speed selections • 4 boiler stages • Adjustable offsets and differentials on relay outputs • Two modulating analog output for speed drive or boiler • Mixing valve control • LEDs for monitoring status • Automatic rotation of pumps • Automatic rotation of boiler stages

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Specs & Docs


General Accuracy: +/- 0.5% Programming: EIA RS485 interface Communications: RS485, half duplex Memory backup: Non-volatile EEPROM, no battery required Environmental Operating temperature: 32 to 131°F (0 to 55°C) Operating humidity: 0 to 100% RH, non-condensing Storage temperature: 14 to 140°F (-10 to 60°C) Electrical Supply voltage: 24 VAC +/-20% Inputs: Six 1000Ω PtRTD, momentary override and five digital (dry contact) Range: Loop water supply and return: 20 to 120°F Condenser water supply and return: 20 to 120°F Boiler water: 40 to 240°F Outdoor air temp: -40 to 160°F Outputs: 12 digital (SPST dry contact, 24 VAC @2A) analog and Two 4 to 20 mA DC Max load resistance (analog output): 600 Ω Common mode rejection: 100 db @ 60 Hz Power consumption: 15 VA max. Specifications subject to change without notice.