Johnson Controls A421ABC-x, A421AEC-x, A421GBF-x, A421GEF-x User Manual

Figure 1: A421 Control with Type 1 (NEMA),

IP20 Enclosure Dimensions, in. (mm)

Figure 2: A421 Control with Type 4X (NEMA),

IP66 Enclosure Dimensions, in. (mm)

A421 Series Standard Electronic Temperature Controls

Installation Instructions

A421ABC-x, A421AEC-x, A421GBF-x, A421GEF-x

Refer to the QuickLIT website for the most up-to-date version of this document.

Applications

IMPORTANT: Use this A421 Series Electronic

Temperature Control only as an operating contr ol. Where failure or malfunction of the A421 control could lead to personal injury or property damage to the controlled equipment or other property, additional precautions must be designed into the control system. Incorporate and maintain other devices, such as supervisory or alarm systems or safety or limit controls, intended to warn of or protect against failure or malfunction of the A421 control.

IMPORTANT: Utiliser ce A421 Series Electronic Temperature Control uniquement en tant que dispositif de régulation. Lorsqu'une défaillance ou un dysfonctionnem ent du A421 control risqu e d e provoquer des blessures ou d'endommager l'équipement contrôlé ou un autre équipement, la conception du système de contrôle doit intégrer des dispositifs de protection supplémentaires. Veiller dans ce cas à intégrer de façon permanente d'autres dispositifs, tels que des systèmes de supervision ou d'alarme, ou des dispositifs de sécurité ou de limitation, ayant une fonction d'avertissement ou de protection en cas de défaillance ou de dysfonctionnement du A421 control.

Part No. 24-7664-3019, Rev. D

Issued March 2016

Dimensions

The A421 Series Electronic Temperature Controls are single-stage, electronic temperature controls with a single-pole, double-throw (SPDT) output relay.

A421 controls feature a backlit LCD with adjustable brightness and three-button tou ch pad interface that can be set up to restrict user adjustments. An LED indicates the output relay's On/Off status.

A421 controls have simple On and Off temperature settings for heating or cooling, an adjustable anti-short cycle delay, temperature setback, and sensor offset capability. The temperature control range is

-40to212°F or -40to100°C. The A421 controls are available either in Type1

(NEMA), IP20 (CE), high-impact plastic enclosures suitable for surface or DIN rail mounting (Figure 1) or in Type 4X (NEMA), IP66 (CE) watertight, corrosion resistant surface mount enclosures (Figure 2).

A421 Series Standard Electronic Temperature Controls Installation Instructions

Parts Included

Each A421 Control includes a Johnson Controls/ PENN® A99 Series temperature sensor. See A99

Series Temperature Sensors, Wiring, and Technical Specifications for more information about A99 se nsors.

A99 Series Temperature Sensors

The A421 controls require an A99 sensor, and each A421 control includes an A99 sensor. Any A99 Series sensor works with the A421 Series controls. Do not replace an A99 Series sensor with any other brand, series, or type of temperature sensor. See Ordering Information for available A99 Series sensor models.

The sensor leads may be extended in the field. See Table 1 for recommended wire sizes and lengths. On long sensor cable runs, use shielded cable to reduce Electro-Magnetic Interference (EMI). Obse rve EMI best practices when routing sensor leads.

The A99 Series sensors are moisture tolerant and splash resistant, but do not completely immerse the A99 sensor in water or any other liquid. Immersing the sensor can allow liquid to enter the sensor pr obe where the stainless steel tube meets the wire cable and result in sensor failure, which voids any warranty.

In applications where the sensor may be exposed to a lot of moisture, splashing, or rain, we recommend mounting the sensor in a vertical position with the cable at the bottom routed downward to allow moisture to drain away from the stainless steel probe. Use a suitable bulb well for complete fluid immersion applications. See Ordering Information recommended bulb well.

The A99 Series sensors are positive temperature coefficient (PTC) sensors. To test an A99 sensor, disconnect the sensor from the control and measure the resistance between the sensor leads:

• When the temperature at the sensor is 77°F (25°C), the resistance should be 1,035 ohms.

• When the temperature at the sensor is 32°F (0°C), the resistance should be 855 ohms.

See Troubleshooting When an A99 sensor is connected to a standard

A421 control, the range of usable values is restricted by the control to -40 to 212°F or -40 to 100°C.

See Wiring

A99B Series Temperature Sensors Product/Technical Bulletin (LIT-125186) for more information regarding

A99 Series sensors.

, Technical Specifications, and refer to the

for more information.

for a

Mounting

Observe the following guidelines when locating and mounting an A421 control:

• Ensure that the mounting surface can support the control, DIN rail, mounting hardware, and any (user-supplied) panel or enclosure.

• Mount the control in a vertical, upright orientation wherever possible. DIN rail mounting is strongly recommended for Type 1 controls.

• In direct-mount applications, mount the control on a flat and even surface.

Mount the control in a location free of corrosive vapors and observe the ambient operating conditions listed in

Technical Specifications

the A99 sensor.

• Allow sufficient space for connecting and routing wires, viewing the LCD, and using the touchpad.

• Do not mount the control on surfaces that are prone to vibration or in a location where high-voltage relays, motor starters, other sources of electromagnetic emissions, or strong radio frequency may cause interference.

• Do not install the control in an airtight enclosure.

• Do not install heat generating devices with the control in an enclosure that may cause the ambient temperature to exceed 150°F (66°C).

To mount a Type 1/IP20 control on DIN rail:

1. Provide a section of 35 mm DIN rail that is longer than the control width, and mount the DIN rail in a suitable location using appropriate mounting hardware.

2. Clip the control module on the rail, position the module’s upper DIN rail clips on the top rail, and gently snap the lower clips on to the bottom of the rail.

To direct-mount a Type 1/IP20 control to a wall or other flat surface using the four keyhole slots:

1. Remove the enclosure cover, place the control vertically against the wall surface in a suitable location, and mark the keyhole slot locations on the mounting surface.

2. Install appropriate screws or fasteners, leaving the screw heads approximately one or two turns away from flush to the mounting surface.

for both the A421 control and

A421 Series Standard Electronic Temperature Controls Installation Instructions

3. Position the control mounting slots over the screw

heads, and then carefully tighten the mounting screws to secure the control to the surface.

4. When mounting the control on an uneven surface, use shims to mount the control evenly on the surface.

Additional Guidelines for Mounting Type 4X/IP66 Controls

The Type 4X models may be mounted to flat vertical surfaces using the four holes at the enclosure corners. Place the control against a flat wall surface in a suit able location, and mark the mounting screw hole locations on the mounting surface. Use appropriate screws and shims to mount the control evenly on the surface.

On Type 4X models, select the knockout to be removed. Place a screwdriver blade on the knockout near the edge. Apply a sharp blow to the screwdriver handle to loosen the knockout. Be careful not to damage the control’s interior components.

An additional low-voltage, two-wire cable is required to operate the A421 control’s temperature setback (BIN) function. On Ty pe 4X/IP66 enclosur es, you mu st inst all a suitable watertight fitting in an available knockout to pass the two-wire cable through the enclosure wall.

The control enclosure base on the Type 4X/IP66 models can be easily rotated 180º relative to the control enclosure cover and LCD, allowing you to bring the electrical connection to either the top or bottom of the mounted control.

Note: Do not twist the wiring harness between the enclosure base and cover more than 180º.

Wiring

WARNING: Risk of Electric Shock.

Disconnect or isolate all power supplies before making electrical connections. More than one disconnection or isolation may be required to completely de-energize equipment. Contact with components carrying hazardous voltage can cause electric shock and may result in severe personal injury or death.

AVERTISSEMENT : Risque de décharge électrique.

Débrancher ou isoler toute alimentation avant de réaliser un raccordement électrique. Plusieurs isolations et débranchements sont peut-être nécessaires pour -couper entièrement l'alimentation de l'équipement. Tout contact avec des composants porteurs de tensions dangereuses risque d'entraîner une décharge électrique et de provoquer des blessures graves, voire mortelles.

IMPORTANT: Use copper conductors only. Make all wiring in accordance with local, national, and regional regulations.

IMPORTANT: Do not exceed the A421 control’s electrical ratings. Exceeding the electrical ratings can result in permanent damage to the control and void any warranty.

IMPORTANT: Run all low-voltage wiring and cables separate from all high-voltage wiring. Shielded cable is strongly recommended for input (sensor) cables that are exposed to high electromagnetic or radio frequency noise.

IMPORTANT: Electrostatic discharge can damage A421 controls. Use proper Electrostatic Discharge (ESD) precautions during installation and servicing to avoid damaging A421 controls.

IMPORTANT: Do not connect supply power to the A421 controls before checking all wire connections. Short circuits or improperly connected wires can result in damage to the modules and void any warranty.

A421 Series Standard Electronic Temperature Controls Installation Instructions

IMPORTANT: When connecting an A99 sensor

Figure 3: TB2 Terminal Block Showing

Connections to the Internal SPDT Relay

with a shielded cable to an A421 Control, connect the cable shield drain lead to the COM (common) terminal on the sensor and binary input terminal block (TB3). Do not connect the shield at any other point along the cable, and isolate and insulate the shield along the entire length of the sensor cable. Connecting a cable shield at more than one point can enable transient currents to flow through the sensor cable shield, which can cause erratic control operation.

Observe the wire size restrictions listed in Table 2 on page 5 and the Electrical Ratings listed in Technical Specifications.

Observe the following guidelines, procedures, and illustrations when wiring an A421 Series control and A99 Series sensor.

• Select only the A99 sensors that are designed to operate in the ambient operating range that your A421 control is intended to monitor and control as shown in Table 7. See Technical Specifications

for

more information.

• Keep the sensor leads as short as possible in your application. The additional resistance in long sensor cables creates an offset between the actual temperature and the displayed temperature. See Table 1 when extending sensor leads.

Table 1: Maximum Recommended Sensor Cable

Lengths and Wire Sizes

Wire Gauge

16 AWG 500 (150) 18 AWG 300 (100) 20 AWG 200 (60) 22 AWG 125 (40)

1. At the listed maximum cable lengths, there is less than 1Fº (0.6Cº) error between the temperature sensed at the A99 sensor and the temperature displayed on the LCD.

Maximum Sensor Cable Length Feet (Meters)

TB2 Terminal Block and SPDT Relay Output

The terminals (LC, LNO, and LNC) on the TB2 terminal block are connected to a SPDT dry-contact relay in the A421 control (Figure 3). The control does not provide any internal power to the TB2 terminals or relay contacts. The A421 control simply energizes and de-energizes the relay to open and close the contacts based on the On/OFF temperature values.

Relay De-energized (Off) = LC open to LNO (as shown in Figure 3) and the relay status LED is off

Relay Energized (On) = LC closed to LNO and the relay status LED is on

• A99 sensors are not polarity specific. Either lead can be connected to the SEN or COM terminals.

• We recommend 22 A WG, stranded, twisted-pair cable with a shield for extending sensor cable runs.

Figure 4 shows how to wire the A421 control to use the same power source that powers the controlled equipment to also power the A421 control.

You can also provide an independent power source for the A421 control on the TB1 terminals and then wire the TB2 relay terminals to a separate power source for switching and powering the controlled equipment circuit.

A421 Series Standard Electronic Temperature Controls Installation Instructions

Figure 4: Wiring the A421 Series Controls Using the Same Power Source

to Power the Control Operation and Power the Controlled Equipment

Table 2: A421 Control Wiring Terminals and Wire Size Information (Part 1 of 2)

Terminal

Label Description, Function, and Requirements Recommended

Block

TB1

24 VAC Models

TB1

120/240 VAC Models

TB2 LC Line-Voltage SPDT Relay Common Contact: Connects power supply to

LN Low-Voltage 24 VAC Control Power (Common): Connect the 24 VAC

supply power to operate the control.

24V Low-Voltage 24 VAC Control Power (Hot): Connect 24 VAC supply

power to operate the control (via jumper from LC in Figure 4).

LN Line-V ol t a ge Power So urce (Common): Connect the neutral wire for 120

VAC supply power applications. Connect the L1 supply power lead for all 208/240 VAC supply power applications.

120V Line-Volt age 120 VAC Control Power (Hot): Connect the 120 VAC

supply power (hot) for 120 VAC supply power applications (via jumper from LC in Figure 4).

240V Line-Voltage 240 VAC Control Power (L2) Terminal: Connect the L2

supply power connection for 208/240 VAC supply power applications (via jumper from LC in Figure 4).

power the controlled load. Connect 24 VAC (hot) for 24 VAC applications; 120 VAC (hot) for 120 VAC applications’ and L2 for 208/240 VAC applications.

LNO Line-Voltage SPDT Relay Normally Open Contact: Connects controlled

equipment to the Line-Voltage Normally Open (LNO) contact on the SPDT relay . W hen LC is closed to LNO , the relay is energized and the green LED is on. The LNO terminal typically provides power to the controlled equipment in both cooling and heating applications.

LNC Line-Voltage SPDT Relay Normally Closed Contact: Connects

controlled equipment to the Line-Voltage Normally Closed (LNC) contact on the SPDT relay. When LC is closed to LNC, the relay is de-energized and the green LED is off. The LNC terminal is not typically wired to the controlled equipment.

Wire Sizes

28 AWG to 12 AWG

0.08 mm2 to 4.0 mm

28 AWG to 12 AWG

0.08 mm

28 AWG to 12 AWG

0.08 mm

to 4.0 mm

A421 Series Standard Electronic Temperature Controls Installation Instructions

Table 2: A421 Control Wiring Terminals and Wire Size Information (Part 2 of 2)

Figure 5: A421 Control Front Panel with LCD

and Three-Button User Interface

Terminal

Label Description, Function, and Requirements Recommended

Block

TB3 BIN Detects a switch closure between the BIN and COM terminals and enables

the selected temperature setback (tSb) value.

COM Connects low-voltage common from the sensor and binary input. SEN Connects low-voltage input signal wire from control sensors.

Wire Sizes

22 AWG (0.34 mm stranded, shielded cable recommended

)

Replacing an A419 Control with an A421 Control: Terminal Locations and Labels

The A421 Series Electronic Temperature Controls are the next generation of the A419 Series Electronic Temperature Controls.

If you need to replace an A419 control with an A421 control, be sure to note that wiring terminals on the TB1 and TB2 terminal blocks on A421 controls are in different positions and have different terminal labels from the wiring terminals on the A419 controls. Table 3 provides a cross-reference for matching the terminal labels on A419 controls to the terminal labels on A421 controls.

Note: The low-voltage signal terminals on the TB3 terminal block are labeled the same on both A419 controls and A421 controls.

See Figure 4 for terminal block and terminal positions on the A421 control.

Table 3: A419 and A421 Wiring Terminal Labels

Terminal Block

TB1

(24 VA C)

TB1

(120/240 VAC)

TB2

(All Voltages)

A419 Terminal Label

T1 LN T2 24V 120 120V 240 240V AC COM LN CLC NO LNO NC LNC

A421 Te rminal Label

Setup and Adjustments

Front Panel

The front panel of the A421 Series Electronic Temperature Control has a simple LCD and a three-button user interface (Figure 5).

Liquid Crystal Display

The A421 Series Control has a backlit LCD screen (Figure 5). The LCD brightness is adjustable. During normal operation, the LCD displays the Main screen, which provides following information:

• the temperature sensed at the A99 sensor

• the selected temperature units (°F or °C)

A421 Series Standard Electronic Temperature Controls Installation Instructions

• the mode of operation (Flame = Heating mode, Snowflake = Cooling mode)

• Binary Input status (BIN) when a (user-supplied) binary input (switch) is connected and closed to enable the temperature setback feature.

During setup and adjustment, the LCD displays the parameter code screens and the parameter value screens. See the A421 Control Parameter Setup Menus on page 9 for more information.

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