http://www.dticorp.com/catalog/honeywell-w973b1016-logic-panel-p-1249.html
HONEYWELL W973B1016 Logic Panel (use with T7067 and Q667), Stages 3 Heat/3 Cool. Control heating, cooling and economizer operation in commercial air conditioning and heat pump equipment.
Features
• Proven, reliable temperature control.
• Many flexible versions to meet your application needs.
• Panels can be used with staged gas, oil, or electric heat; modulating gas, hot water, or steam heat; and direct expansion or modulating chilled water cooling.
• Control up to 3 on-off heat or cool stages or up to 10 on-off heat and/or cool stages using W975 Satellite Sequencers.
• Modulating dc current signal controls economizer heating or cooling valve motors.
• T7067 Dual Set Point Thermostat/Transmitter located in controlled space provides heating and cooling input signal based on space demand.
• C7046A sensor located in discharge air duct provides heating/cooling anticipation and economizer modulating low limit signal.
• System cycles all stages off on power interruption.
• When power is restored, system sequences required stages on with timed inter-stage delay.