• Contact points

The contact point is the core part of the heating contactor and is responsible for establishing or interrupting the circuit. Made of silver alloy to withstand frequent switching operations without easy wear.

• Coil

The coil acts as an electromagnet, generating a magnetic field when energized, attracting contact points to close the circuit, allowing current to flow to the connected heating element or other HVAC components.

• Enclosures

The housing is used to protect the internal components of the contactor from dust, moisture and other environmental factors. It ensures reliable operation of the contactor under various conditions.

• Terminals

Terminals are interfaces for connecting wires, allowing the contactor to be integrated into the HVAC system. Proper fixing and insulation of the terminals is essential to prevent electrical failures.

• Auxiliary touchpoints (Auxiliary Contacts)

Auxiliary touchpoints are often used to control other circuits or provide feedback signals. They can be normally open or normally closed to help implement more complex control logic.

• Overload protector (Overload Relay)

Some heating contactors are also equipped with an overload protector to monitor current and prevent equipment from being damaged by overload. When an overload is detected, the overload protector cuts off the power.

These components work together to enable the heating contactor to effectively control the flow of current in the HVAC system, ensuring the safe and efficient operation of the equipment.

Proper connection and maintenance of heating contactors is key to ensuring the efficient and safe operation of your heating system. Here are some important steps and recommendations:

1. Main components

• Coil Terminals (A1 and A2): Connect to the control voltage.
• Inlet Terminals (L1 and L2): Connect to the main power supply.
• Load Terminals (T1 and T2): connected to the heating element.

2. Connect the contactor correctly

• Power-off operation:
  • Before making any connections, make sure to cut off the power supply to avoid the risk of electric shock.
• Connect the control line:
  • Connect the thermostat control cable to the A1 and A2 terminals of the contactor.
  • Make sure these connections are secure to avoid malfunctions caused by loosening.
• Connect the main power supply:
  • Connect the main power cord to the L1 and L2 terminals.
  • Make sure to use wires of the right size to withstand the required load.
• Load connection:
  • Connect the heating element to terminals T1 and T2.
  • Make sure all connections comply with the manufacturer’s wiring diagram.

3. Maintenance advice

• Periodic inspection:
  • Periodically check the contactor for burns or corrosion, especially at the contact point. These problems may cause the contactor to fail.
• Test with a multimeter:
  • Use a multimeter to check the voltage at the coil terminals, making sure there is a 24 volt input when powered on. If not, the contactor may need to be replaced.
• Clean and insect-proof:
  • Keep the contactor clean to prevent insects such as ants from gathering, which may affect its normal operation.
• Professional assistance:
  • If you are not familiar with electrical work, it is recommended to seek the assistance of a professional HVAC technician to ensure a safe and correct installation.

By following these steps, the heated contactor can be effectively connected and maintained, thus enhancing the performance of the equipment and extending its service life.

Heating contactors may experience multiple faults during use, requiring replacement. Here are some common situations and suggestions for dealing with them:

In the case of replacing the contactor

• Coil failure

Coil damage: If the coil is open or short-circuited, it is usually necessary to replace the coil. It can be judged by measuring the resistance of the coil with a multimeter.

Overheating: When the power supply voltage is too high or too low, or a short circuit occurs inside the coil, it may cause the coil to overheat and burn out, in which case it also needs to be replaced.

• Contact problem

Contact wear: When the contact is worn to 1/3 of its original thickness or open welding occurs, the contact should be replaced to ensure good electrical contact.

Contact fusion welding: If the contact is fused due to a short circuit of the load or low operating voltage, the contact must be replaced and the load condition checked.

• Frequent starting or excessive load

If the heating contactor operates under frequent starts or when the load exceeds the rated current, it may be damaged. At this time, a larger capacity contactor should be considered for replacement.

• poor suction

When the AC contactor cannot be sucked in or released slowly, it may be due to mechanical failure, spring failure or unstable power supply voltage. If it still does not work normally after adjustment, the contactor needs to be replaced.

• Environmental factors

Contactors used in harsh environments (e.g. humidity, high temperatures, etc.) will have a shorter lifespan if they are not maintained in a timely manner, and may need to be replaced in advance to avoid equipment failure.

1. Regularly check the power supply voltage, terminals, and mechanical components to prevent malfunctions.
2. Make sure the load is within the rated range of the contactor, and clean the contacts and poles regularly to extend the service life.
3. Monitor the working condition of the contactor. If abnormal noise or temperature rise is found, it should be inspected and maintained in a timely manner.
4. With the above measures, it is possible to effectively identify when an AC contactor needs to be replaced and take appropriate precautions to prolong its service life.