Honeywell LP900A 1066 Grad-U-Stat Pneumatic Thermostat 80-120F New

Honeywell LP900A 1066 Grad-U-Stat Pneumatic Thermostat 80-120F New

The Honeywell LP900A 1066 is a Grad-U-Stat pneumatic thermostat designed for temperature sensing and control in industrial and commercial HVAC applications. It uses a copper capillary bulb sensing element to detect ambient or duct temperature and modulates a pneumatic control signal in response, making it compatible with pneumatic control systems common in commercial buildings and industrial facilities. This unit covers a sensing range of 80°F to 120°F and was produced by the Honeywell Aeronautical Division.

Specifications & What's Included

• Manufacturer: Honeywell Aeronautical Division
• Model / Part Number: LP900A 1066 (stamped on base: LP900A 1066 1 FG)
• Series: Grad-U-Stat
• Type: Pneumatic capillary thermostat
• Temperature Range: 80°F to 120°F (graduated scale visible on front window)
• Sensing Element: Copper capillary bulb probe
• Control Type: Pneumatic (modulating)
• Hardware Revision: FG
• Includes: Thermostat body, copper capillary bulb sensor with coiled tubing, and metal mounting bracket
• Open box — new and unused; original box may not be present

Applications

Pneumatic thermostats like the Honeywell LP900A are used in commercial building HVAC systems where pneumatic controls govern heating, ventilating, and air conditioning equipment. The capillary bulb design allows the sensing element to be positioned remotely — in a duct, a return air plenum, or an equipment space — while the thermostat body with its pneumatic output is mounted nearby on a wall or panel. These controls are standard in older commercial and industrial buildings built or retrofitted during the mid-to-late 20th century, and they remain in active service wherever pneumatic HVAC infrastructure has not yet been converted to direct digital control (DDC). The 80–120°F range suits heating-season control, warm supply air sensing, and process temperature monitoring in light industrial environments. Honeywell's Aeronautical Division produced thermostats and environmental control components for both aviation ground-support applications and industrial systems requiring rugged, reliable pneumatic sensing.