The Quantem Series 21 "single stage" thermostat offers the "Ag producer" and/or greenhouse grower a simple, yet economical and reliable control, for regulation of fan motors and/or heaters. The Model 21 is specifically designed for harsh environments where the ambient is likely to see high humidity and/or moderately corrosive contaminates. It is ideal for applications, such as poultry houses, hog houses, and greenhouses.

It is simple to install and operate. This wall mount design does not require set point knob clearance, so it may be mounted in small spaces. The unit consists of a single pole double throw switch with a liquid filled sensing bulb and bellows. This  mechanical thermostat does not require supply voltage and will switch 100 to 250VAC. Temperature can be set using the large easy to read dial.

The special low mass, stainless steel, sensing bulb, provides rapid response to temperature changes. The sensor is mounted the thermostat's sealed housing. A flexible mounting and water tight gasketed design that meets Article 547-4 of the National Electric Code, assure its suitability for a tough environment.

Operation of the Series 21 control is by expansion or contraction of liquid in response to temperature changes. The liquid, contained inside the stainless steel coiled sensor, activates a diaphragm connected to a precision snap action switch.

Series 21 is designed for wall mounting. Its unique packaging protects critical component circuitry against dust and moisture.