Variable Frequency drives or VFD’s have been around now for over 20 years. Although earlier versions were limited depending on the horsepower of the system, today’s variable frequency drives can be in commercial and industrial pumps and motors of up to 500 horsepower. VFD’s are one of the most effective energy management tools ever implemented onto HVAC systems.
So what exactly are VFD’s and how do they work congruently with your HVAC system?
Most HVAC systems are configured to operate at a consistent speed, regardless of the system demands that are needed from the user.
As we are all well aware, the actual building load demand is anything but constant. Regardless of what the heating or cooling demands are on the system, the drive motor continues to operate at full speed throughout the day.
The VFD allows the drive motor to gradually begin operating when the demand is needed, instead of operating at full throttle when such power isn’t needed.
Since HVAC systems are designed to work specifically for peak load parameters, the wasted energy consumption occurs during the times where peak load conditions are not required, which astoundingly enough is approximately 95 to 99 percent of normal operating hours.
With that being said, the energy that the motor expends is all dependent on the speed of the motor. With the addition of a VFD regulating and reducing the speed of the motor by 25 percent, you can see a tangible reduction in your bill by nearly 60%!!
Now let’s take a closer look at the top 10 reasons why you should install a VFD on your commercial HVAC equipment:
- Energy savings from 35-60% compared to conventional constant speed applications.
- Decrease in demand charges. Another result of decreasing energy expenditure in your building during peak demand time will also decrease your demand charge which will also reflects in your electric bill.
- Return on your investment in as little as 6 months to 2 years!!
- Reduced wear and tear on the motor. Reducing the amount of start and stops on the motors reduces the chances of early motor failure.
- Extending the life of the motor. The VFD allows a controlled low voltage increase to the motor to achieve normal operating conditions. This controlled constant increase of frequency and voltage will ultimately extend the life of the motor by allowing for a softer start to the motor.
- More exact control over a wider range of flow rates, resulting in reduced wear on the pump and increased energy savings.
- Variable speed drives have a more specific process control. A VFD can have the motor run at a precise speed, apply a specific amount of torque or stop at an exact position.
- Most HVAC systems designs are over-sized for the facility in order to anticipate any future additional loads like new equipment or additional people. A VFD allows for a more accurate assessment of what the load to the motor should be and at what speed it should be running at in order to maximize efficiency.
- Eliminate water hammer problems by slowly regulating the water flow to reduce any pipe rupturing or leaks to the system.
- Provide diagnostic data. By providing a constant analysis on how the system is performing, you are able to track performance and catch any underlying issues before they become costly problems. Being proactive is key when it comes to conserving equipment and energy savings!!
So on what specific HVAC equipment would I be able to use a VFD and start generating these energy savings?
- Chiller pump motor- regulates or modulates the flow of water depending on cooling demand by either increasing or decreasing the GPM (gallons per minute).
- Cooling tower fan motor, condenser water pumps and boiler pumps- manipulates the current of the cooling tower fan motor which drops the speed of the fan motor according to the demand of the building.
With so many positive factors to focus on with installing a variable frequency drive, it’s no wonder why we are seeing such an increase of these drives being installed in the HVAC industry today.
AC Power & Comfort focuses on helping building owners, property managers, and facility professionals lower their operating expenses and energy costs through proactive HVAC maintenance and energy saving equipment. Contact us to set up an appointment to see how a VFD installation can start saving you money today!