COVNA Actuator In The HVAC System

Unless you are a trained HVAC technician or a do-it-yourself nerd, chances are you won’t bother figuring out the technical bits of your HVAC system. In fact, when every component is working right, there is a tendency to take for granted the comfort and air quality you enjoy.

One of the greatest innovations in HVAC which you are probably already enjoying is climate control in multiple zones in your home. If you live in a two-story building, you may want the upper rooms cooler and the lower rooms warmer. Alternatively, you may want certain spaces in your house such as bedroom to be warmer while areas like the kitchen cooler.

While all components in an HVAC system work together to achieve this, two of the most critical are the HVAC damper and actuator. They work together to ensure airflow into the different spaces in your house is properly regulated.

What Is an Actuator

An actuator is a device that takes in energy and converts it into a turning effect around an axis or torque which then helps to move or control a system. In HVAC systems, actuators are fitted into dampers to control their opening and closing. In turn, this regulates the flow of air through the ductwork into your individual rooms.

Actuators have a control system that is operated electronically, mechanically or through custom software. Depending on the operating mechanism, an actuator can either introduce motion or prevent it.

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Components of an Actuator

To understand the role an actuator plays in regulating the different positions between open and close in a damper, the best place to begin is in looking at its components.

  • Clevis -Depending on the actuator design there could be both front and rear clevis. Basically, the clevis is the point of attachment of the actuator to the damper.
  • Outer Tube – This is the outermost casing of the actuator. It protects all the inner components from direct exposure to the elements.
  • Inner tube- This tube houses the spindle and is made of steel or aluminium. It retracts and extends as the threaded drive nut moves along the spindle.
  • Spindle-  This is the part of the actuator that rotates and is also known as the lifting screw or lead screw. The spindle rotation creates a linear movement much like the wheel system of vehicles. Depending on the speed and load capabilities the spindle can be threaded in different ways for strength and durability.
  • Safety Stop-This is a component positioned at the end of the spindle. Its function is to prevent the inner tube from extending beyond the allowable limits.
  • Wiper- This component ensures liquids and dust do not get into the spindle mechanism. It is normally located at the very end of the outer tube.
  • Drive Nut -Attached to the inner tube, this is a plastic or metallic nut that moves along the spindle. This motion controls the extension and retraction of the inner tube.
  • Limit Switches- These switches prevent the inner tube from overextending and over retracting by cutting the electric current from the motor.
  • Gear- This is a little plastic or steel gear that mates with the gear on the HVAC damper to control the speed of the closing and opening motion.
  • Motor- This is the power-generation unit of the actuator. Depending on the design, this could be a DC or an AC motor.
  • Feedback Sensors—There are different types of sensors such as reed sensor, Hall Effect sensor, and Potentiometer Sensor. The work of the sensors is to communicate the stroke position of the actuator to the micro control unit (MCU).

How Actuators Work In  HVAC System

Having looked at the different components of the actuator, you can almost figure out how the actuator works in an HVAC system. However, before we go into the mechanism of operation, it helps to know that there are different types of actuators, the main ones being electric and pneumatic.

Electric Valve Actuators

These actuators are powered by electric energy that comes from a motor which could be DC or AC. The choice of power source (AC or DC) depends on the application. In large industrial HVAC applications, AC motors are preferred because of the ease of conversion from higher to lower voltages.

On the other hand, DC motors are typically used in residential HVAC systems and in other lower power applications. Most motors are 12V DC though other voltages are also available.

How the electric valve actuator works is simple. The voltage first hits the primary unit or the stator assembly. This turns the voltage into a current which is then pushed into the rotor assembly. Both the stator and rotor assembly work together resulting in an electromagnetic field.

The field created, counteracts the spring that normally holds the drive nut in place through brake pads. One the braking force is released the drive nut moves along the spindle causing a linear motion that extends the inner tube.

As the tube moves, the gear on the actuator mates with the damper gear mechanism forcing the damper to open allowing air to flow through the ductwork to the specific rooms as required. DC brushes play a critical role in conveying current to the leadscrew.

Pneumatic Valve Actuators

Theses actuators depend on pressurized gas to convert energy into motion. The air could either be lubricated or dry. The compressor reduces the air volume and this causes the gas pressure to increase.

The pressured gas then moves through a system of horses and valves into the actuator. Once the compressed air enters the actuators cylinder, it moved the lead screw or piston causing motion which could either be linear or rotary.

Enhancing HVAC Efficiency and Savings through COVNA Valve Actuators

COVNA is one of the leading manufacturers of actuators ranging from pneumatic to electric to solenoid valve actuators. Their products made through patented German technology have unique features that make them useful in different applications.

Their electric valve and pneumatic valve actuators are particularly designed for both modern and legacy HVAC systems. Here is how they stand out.

Smooth Exterior Profile

On the outside, both the electric and pneumatic valve actuators have a continuous surface design with no cavities of grooves. This ensures dirt and debris don’t accumulate. In turn, this design reduces the maintenance burden.

Corrosive-Free

The hard, anodized aluminium alloy that makes the outer cylinder of COVNA valve actuators gives them protection against corrosion. The piston is made of galvanized cast steel and all gasket interfaces are sealed giving an IP67 rating. This robust design means the actuators can even move directly in the path of water.

More Torque In a Smaller Casing

The motor is smaller in size but generates a larger torque pushing the piston to take up much larger loads.

Travel Life

The diameter of the lead screw stacks up well against competition. A larger diameter means the COVNA pneumatic and electric valve actuators are much more reliable and have a longer travel life. On load life curves, COVNA valve actuators can easily take up 750N of load over a distance of about 8,000km.

Quick and Easy Installation

The actuator mounting process is faster, simpler and eliminates the risk of misalignment. Both the shaft and the motor are not subjected to any radial load.This reduces the setup time and boosts installation efficiency.

In addition, COVNA has a strong team of quality assurance experts and application engineers that can work with you to help you optimize your HVAC application.