Description
The Johnson Controls A19ADB-2 is a mechanical hot water immersion temperature control engineered for reliable, precise monitoring and switching in hydronic heating and hot water systems. Featuring a wide 100°F to 240°F setpoint range and a convenient knob range adjuster, this control gives technicians and system designers the flexibility to dial in exact operating thresholds without the need for additional tools or programming.
Key Features
- Mechanical temperature control — no electronics or programming required for dependable operation
- Wide setpoint range of 100°F to 240°F, adjustable via knob range adjuster for easy field configuration
- SPST (Single-Pole, Single-Throw) switching action with Open High operation — opens the circuit as temperature rises above setpoint
- Manual reset function provides added safety by requiring deliberate operator action to restore the circuit after a trip event
- Broad voltage compatibility: 24 to 277VAC, suitable for a wide range of commercial and residential control circuits
- 1/2″ NPT well connector for secure, leak-free immersion installation into hot water pipes, boilers, and hydronic systems
Specifications
- Brand: Johnson Controls
- Model / SKU: A19ADB-2
- Control Type: Mechanical Temperature Control
- Application: Hot Water Immersion
- Switching Action: SPST, Open High
- Reset Type: Manual Reset
- Setpoint Range: 100°F to 240°F
- Voltage Rating: 24 to 277VAC
- Well Connection: 1/2″ NPT
- Setpoint Adjustment: Knob Range Adjuster
Applications
- Hot water boiler high-limit protection
- Hydronic heating system temperature control
- Commercial and residential hot water supply monitoring
- Immersion-style temperature switching in piped water systems
The A19ADB-2’s manual reset design makes it an ideal safety control — once the water temperature exceeds the setpoint, the circuit opens and stays open until an operator manually resets it, preventing automatic restart under potentially unsafe conditions. The 1/2″ NPT well connector ensures a standard, secure fit in most common pipe and boiler well configurations.
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