Johnson Controls Multiple Stage Thermostat System for Pump Tank and Pumping Systems

Pictured is the A350 multi-stage electronic temperature control system thermostat manufactured by Johnson Controls.

Factory installations of the A350 include :

• Chilled water systems
• Tower water systems

Field Installation :

• The A350 can also be field installed for single unit replacement of manual thermostats used on tower applications.
• It is approved for use on UL listed panels.
• The assembly is DIN rail mounted on the electrical panel. The assembly pictured on this page is from a PTS-800 system and operates the tower pump, tower fan and alarm.

The A350 consists of :

• Analog set point module
• Power module
• Digital display module
• Up to 9 staging modules. There is a 2°F minimum differential between staging modules. The staging modules activate at an adjustable offset from a common setpoint. The differential between "on" and "off" can also be adjusted on each module.

Typical Settings :

• Tower Pump: offset 0°F
• Tower Fan: offset 5°F
• Tower Fan: differential 7°F
• Alarm: offset 20°F
• Setpoint: 80°F