To Next PageTo Next Page
Need help?Do you have a question about the Johnson Controls Penn A421 Series and is the answer not in the manual?
Details the A421 Series Standard Electronic Controls with SPDT relay, LCD, touchpad, and LED indicator.
Explains setting defrost periods, intervals, and manual activation methods for the A421 Control with Defrost.
Covers sensor offset, temperature setback, anti-short cycle delay, and user adjustment modes.
Details Type 1, IP20 and Type 4X, IP66 enclosures for surface or DIN rail mounting.
Lists sample temperature control applications for refrigeration and HVAC equipment.
Displays temperature, parameters, status, backlight intensity, and custom icons.
Offers two levels of parameter adjustment and control for setup.
Covers On/Off adjustment, switch-activated setback, and anti-short cycle delay.
Details adjustable sensor offset, restricted adjustment mode, and sensor failure behavior.
Covers LCD backlight adjustment and guidance for repairs.
Guides on ordering sensors, hardware, and accessories from distributors.
Lists A421 models, enclosures, and included sensors with their specifications.
Details various A99 PTC temperature sensors, probe types, cable lengths, and operating ranges.
Lists available accessories like DIN rail sections, clamps, clips, sun shields, and enclosures.
Provides detailed specs for power, supply, ambient conditions, temp range, sensor, enclosure, and compliance.
Outlines terms of use for the product's software and hosted services.
Lists regional contact points and provides links for customer support.
States the product is covered by a limited warranty with details available online.
The A421 Series Electronic Temperature Controls are single-stage, electronic temperature controls equipped with a single-pole, double-throw (SPDT) output relay. These controls are designed to manage a wide range of single-stage refrigeration or HVAC equipment, making them suitable for applications such as on/off control chillers, chiller pump control, and general cooling control.
A key feature of the A421 Series is its adjustable backlit LCD, which provides clear visibility of the current temperature and the status of various other functions. The backlight intensity can be adjusted to suit ambient light conditions, and custom icons are used to display system and control status at a glance. Interaction with the device is facilitated by a three-button touchpad, which allows for easy setup and adjustment of parameters. An LED indicator further enhances usability by showing the On/Off status of the output relay. The A421 Controls are available in both 120 VAC and 240 VAC models to accommodate different power requirements.
For applications requiring defrost capabilities, the A421 Control with Defrost offers flexible configuration options. Users can set up regular, passive defrost periods ranging from 1 minute to 99 minutes. The interval between defrost cycles is also adjustable, from 2 hours to 24 hours, or it can be set to 0 if no defrost interval is desired. Manual control over defrost cycles is also provided; a defrost off-cycle can be initiated or stopped in two ways: either by pressing the three-button touchpad within the Advanced Menu or by connecting a momentary switch to the Binary Input (BIN).
Beyond temperature and defrost control, the A421 offers several advanced features to optimize system performance and user experience. These include sensor offset adjustment, which allows the displayed temperature to be calibrated to the actual sensed temperature. Temperature setback functionality is available, enabling a shift in the On/Off temperature by an adjustable amount. This setback can be activated when a user-supplied switch closes the binary input control circuit. An adjustable anti-short cycle delay (ASd) is also incorporated, allowing users to select a minimum time the output relay must remain off before the next on-cycle. This feature is crucial for preventing short cycling, hard starts, and nuisance overload outages, particularly in applications involving compressors and other inductive loads.
The A421 also provides a restricted user adjustment mode, which can limit the On/Off adjustment to a defined temperature range. This is useful for maintaining specific operational boundaries. Users can choose to display temperature units in either Fahrenheit (°F) or Celsius (°C). The temperature adjustment range is broad, spanning from -40°F to 212°F or -40°C to 100°C, making it suitable for a wide array of applications.
In terms of enclosure options, the A421 Controls are available in two main types. Type 1, IP20 high-impact plastic enclosures are designed for surface or DIN rail mounting, offering a robust solution for indoor installations. For more demanding environments, Type 4X, IP66 watertight, corrosion-resistant surface mount enclosures are available, providing enhanced protection against water and corrosive elements.
The control features a basic and advanced programming menu, offering two levels of parameter adjustment. The advanced menu allows for the setup of sophisticated features, while the basic menu is used for adjusting fundamental parameters. This dual-level approach caters to both novice and experienced users. The On/Off temperature adjustment allows users to select the specific temperature values at which the relay turns on and off, automatically defining the mode of operation.
Maintenance and repair information emphasizes that users should not attempt to repair or recalibrate the A421 Series Electronic Temperature Control themselves. In the event of a defective or improperly functioning control, users are advised to contact their nearest authorized Johnson Controls or PENN distributor or sales representative. When seeking support, it is important to have the model number of the control available, which can be found on the label inside the cover of the control. This ensures accurate and efficient assistance.
For ordering additional components, users should contact their local Johnson Controls or PENN distributor or sales representative to acquire sensors, mounting hardware, and other accessories necessary for installing the A421 Controls. Information regarding options for high-volume purchase models with specific application requirements can also be obtained from these representatives.
General| Power Consumption | 5 VA max |
|---|---|
| Relative Humidity | non-condensing |
| Output Type | Relay |
| Mounting | Surface mount |
| Control Mode | On/Off |
| Enclosure Rating | NEMA 1 |
| Input Types | Thermistor |
| Sensor Type | Thermistor |
