Armstrong 20J99 Auto Limit SwitchArmstrong 20J99 delivers dependable performance as a 130 160F auto limit switch designed for HVAC systems and industrial controls. This compact sensor automatically disconnects equipment when the temperature hits the preset range, safeguarding motors, fans, and components from overheating. With a rugged design built to withstand demanding environments, the Armstrong 20J99 provides reliable temperature sensing and repeatable switching across cycles.

This replacement part supports routine maintenance

ensuring dependable performance across a range of gas systems

while a blue 12 sq in display keeps settings clear at a glance

3/4" threaded connections

8 A input current

termination 300°F

It features durable construction and broad coil voltage compatibility

making it ideal for homes with mixed systems

As a trusted gas furnace replacement part

this compact unit blends durability with precise actuation to deliver stable

It is specifically intended for AO Smith commercial gas water heaters in the BTR/BTRC families

Diaphragm operator: responsive sensing using air as the pressure media