Johnson Controls A19ZBA-1 Temperature Control

The Johnson Controls A19ZBA-1 Temperature Control is a heavy-duty mechanical switch purpose-built for water chiller temperature control and refrigeration applications. Designed for reliability in demanding commercial environments, this remote bulb temperature control utilizes a liquid-filled sensing element to provide high-accuracy "repeat" performance that remains unaffected by barometric pressure or cross-ambient temperature fluctuations. This SPST (Single Pole Single Throw) controller features an automatic reset and is configured to open low (cut out on temperature drop) and close high, making it an essential component for preventing freeze-ups and maintaining precise setpoints in fluid cooling systems.

For flexible field integration, the A19ZBA-1 offers a broad setpoint range of 38 to 80°F and an adjustable differential from 8 to 40°F. The 6-foot capillary leads to a 3/8" x 3 7/16" sensing bulb, which can be used for air sensing or immersion in a closed tank when paired with a compatible bulb well. Built to handle a wide voltage range from 24 to 277Vac, this HVACR mechanical thermostat provides technicians with a robust, field-proven solution for chiller system maintenance and industrial temperature regulation.

Key Benefits

• Broad Compatibility: Supports electrical loads from 24Vac to 277Vac, fitting most commercial mechanical temperature control wiring configurations.
• High Accuracy: The liquid-filled element ensures the adjustable differential temperature control stays calibrated despite changes in ambient conditions.
• Ease of Adjustment: Features a visible dial and knob range adjuster for quick setpoint changes, with a concealed differential adjustment to prevent unauthorized tampering.
• Application Versatility: Ideal for water chillers, walk-in coolers, and general-purpose refrigeration requiring an automatic reset temperature switch.

Common Questions

Does this control require a separate bulb well for immersion?
Yes, for closed-tank or pressurized liquid applications, a 3/8 inch bulb well (such as the WEL14A-600R) is recommended to protect the capillary and allow for easy replacement without draining the system.

How do I adjust the cutout and cut-in points?
The cut-in temperature is set using the external knob. The cutout point is then determined by the adjustable differential setting located under the cover, allowing you to fine-tune the cycle time for chiller compressor protection.

Can this be used for heating applications?
The A19ZBA-1 is specifically designed to open on temperature drop. For heating applications where you need the contacts to open on temperature rise, a different model in the A19 series with "Open High" logic would be required.

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Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.