Programmable 365-Day Modulating Thermostat

The SZ1050 Series has a 365-day time clock. The SZ1051 is designed to control air handling units with modulating economizers and modulating heating or cooling. The SZ1053 controls air handling units with modulating heating and cooling.

• Stand-alone or network operation
• 365-day time clock with one holiday schedule with automatic leap year and daylight savings correction
• Discharge air sensor input with high and low limits (and reset with the SZ1053)
• Discharge air heating low limit
• Outdoor air sensor input with heating & cooling lockouts (and economizer operation with the SZ1051)
• Two stages for heating and/or cooling
• Modulating outputs for heating and/or cooling
• Adjustable delay on power-up and start-up for soft starts
• P+I control option on digital stages
• Smart Recovery
• 32 character LCD display
• Six status LEDs
• Remote room sensing capability
• User setpoint adjustment limits
• Local override and remote override capability
• System and fan switching with access lockouts
• Auxiliary time clock output
• Fan interlock safety option
• Filter service input and indication
• Equipment monitoring inputs and indication
• External time clock input
• Energy management input for setpoint shift
• Access to programming or schedule may be locked out or limited with the use of an access code
• Fahrenheit or Celsius temperature display
• Digital enthalpy switch input for economizer enable on the (SZ1051)

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Specs & Docs



Accuracy: +/- 1ºF at 75ºF
Display resolution:+/-1°F (0.6°C)
Display: 32-character LCD
Programming: Front panel keypad or EIA RS485 interface
Communications: RS485, half duplex
Memory backup: Non-volatile EEPROM, no battery required
Program Setting: 2 events per day with 7 days per week and 2 holiday schedules (12 periods of up to 99 days each)
Override: Programmable from 0 to 255 minutes


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)


Supply voltage: 24 VAC +/- 20%
Inputs: Built-in and remote platinum RTDs, momentary override and three digital (dry contact)
Range: Room Temp: 40 to 90°F (built-in or remote)
Outdoor Air Temp: -40 to 160°F (remote)
Discharge Air Temp: 0 to 150°F (remote)
Outputs: Four digital (SPST dry contact, 24 VAC @ 2 A), two 4-20 mA DC analog
Max. Load Resistance (analog output): 600 Ω
Common mode rejection: 100 db @ 60 Hz
Power Consumption: 8 VA max.

Specifications subject to change without notice.