What is VFD in HVAC? https://searchlocalpro.com/what-is-vfd-in-hvac/

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December 2, 2022
What is VFD in HVAC?
searchlocalpro.com/what-is-vfd-in-hvac/
You might be tired of your heating and cooling system’s inefficiency or just want to
increase your knowledge regarding important HVAC components. Either case, we are
here today to answer your question, i.e., what is VFD in HVAC? So that you can
understand how this little integration boosts the working potential of your HVAC unit.
Consequently, VFD stands for Variable Frequency Drive (VFD) and is a motor controller
that controls the speed and torque of an electric motor. It does this by adjusting the
frequency and voltage supplied to the motor and changing its rotational speed.
However, to find profound insights regarding the magical VFD system, let’s dig in a little
more and reveal the ultimate secret!
Variable Frequency Driver (VFD): A Comprehensive Guide
A Variable Frequency Driver (VFD) is an electro-mechanical device that controls the
speed of rotations of an electric motor by managing its Alternating Current (AC) supply. It
varies the frequencies and voltage of the power supply in response to the overall motors’
current load.
Also known as AFDs ( Adjustable Frequency Drivers), ASDs (Adjustable Speed Drivers),
VSDs ( Variable Speed Drivers), ACD (Alternating Current Drivers), micro drivers, and
inverter drivers, VFDs work on the principle of controlling the motor and boosting the
systems’ efficiency and functionality ratio.
Common VFDs Application:
Alternating Current motors
Electro-mechanical pumps
Air volume systems
Elevators
Agitators
Cooling towers
Heating systems
Force Draught fans
Conveyor systems
Injection molding machines
Rollers and blowers
Wire drawing machines
Furnace fans of drying machines
Weighing and packing machines
HVAC systems

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VFDs in HVAC System: Major Considerations
The commercial or domestic sector HVAC systems are designed to operate effectively at
the peak power supply level. However, the power supply is not constant all the time.
And this low-power or fluctuating supply damages the motors and other components of
the HVAC system and affects the HVAC system’s efficiency and functionality.
And this is precisely where Variable Frequency Drivers jump in and show their magic!
VFDs moderates the motor speed of HVAC systems by converting the Alternating Current
(AC) from the circuit into Direct Current (DC) by passing it through the diode bridge
rectifier
Then through the filter and finally into the inverting section where its frequencies and
voltage are managed and smoothed. From the inverter, the current then passes into the
motor with the help of a high-speed bipolar transistor.
The most significant advantage of using a VFD in HVAC systems is that all electronic
systems receive an appropriate amount of current supply. However, there’s a hell lot more
about VFDs, such as;
Reduction in Energy Bills
Using a VFD in your HVAC system can make your system functional at lower power
levels, which can result in a massive reduction in energy bills.

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If the VFD reduces the motor rotation speed by 25%, your system’s energy consumption
will decrease by up to 60%, according to the studies of Affinity Laws for Centrifugal
Pumps and Fans.
And if the motor speed is cut down to 50%, the energy consumption will be 80% to 90%
less, which will significantly impact your power bills.
Management of the Extra Demand Charges
Commercial setups like hospitals, offices, industries, and factories have to pay extra
demand charges for electricity if they have a large number of HVAC systems, requiring
power peaks during particular seasons of the year.
This refers to the extra working of multiple heating systems in winter or Air conditioners
only in summer.
However, installing VFDs in HVAC can help the owner reduce these demand charges to a
greater extent by managing the power and current supply to the motors.
Prolongs the LifeSpan of Motor and Other Components
As the HVAC systems are considered heavy electro-mechanical machines, they require
high-efficiency motors that have worked constantly for years.
But for several reasons, the components of HVAC systems, especially motor systems,
start to decrease their working capabilities and deteriorate enough that they either
damage the other parts of the system or badly affect its efficiency.
Even if you regularly have maintenance and repair of your system, you cannot simply
stop the process of motor deterioration.
However, using a VFD in HVAC systems can slow down the process and prolong your
motor and other components’ life.
Boost the Working Capacity of Your HVAC Systems
The starting point of any system’s low efficiency or malfunctioning starts when the
system’s power requirements are not fulfilled.
But if you installed a VFD in your HVAC system, it will not only control the overflow or
underflow of the current from the circuit but manage its frequency and voltage according
to the needs of the motor.
And this will eventually result in increased efficiency of your HVAC system.
Applications of VFDs in HVAC Systems

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1. Chilled And Hot Water Systems
Collectively, in the chilled water systems and condensing water systems, including
chillers, chilling water pumps, main bypass pipe, chilling fans coils units, and pumping
systems, the VFDs are installed at the chilled water pumps and on the fans of cooling
towers.
Installing VFDs results in reduced water flow in the pump, which helps lessen the power
consumption in the system.
In comparison, the VFDs placed on the cooling tower’s fans are beneficial as it optimizes
the fans to maintain the temperature of the condensing water leaving the cooling tower
into pipes.
While in the hot water system, the VFDs are installed in both primary and secondary hot
water pumps to track the amount of water entering the secondary pump through passing
the primary pump from the boiler should be sufficient.
In contrast, the VFD at the secondary water pump manages the supply and regulates
water temperature.
2. Air Compressors
Staging control is the factor that manages the on-off and supply of compressed air to the
users. If the demand for compressed air increases, multiple compressors will start
working simultaneously.

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And if the demand increases, the staging control will shut down the compressors.
However, the issue is that these continuous on-off cycles of compressors can negatively
affect their motor and other components and their efficiency.
So, suppose the VFDs are installed at each compressor. In that case, the flow and
supply-demand of the compressed air through the compressors can be effectively
handled, resulting in increased working ability and a prolonged life span.
3. Ventilation System
A ventilation system has become a modern-day need of every building, whether a
hospital, school, kitchen, or office. It is needed to supply fresh air continuously and
exhaust air to keep the balance.
A ventilation system contains an air-handling unit, an air makeup unit, and a fresh-air unit
from where fresh air is introduced into the rooms.
The VFD is installed on the air exhaust system, particularly the exhaust fan, to maintain
the required building pressure and complete the airflow difference between the demanded
and supplied air.
4. Refrigeration System
VFDs are also installed on the compressors, condenser fans, and evaporating fans of
refrigeration systems to maintain power and energy flow through the HVAC system. It
slows down the speed of the motor and provides variable frequencies and voltages
necessary to maintain a uniform temperature.
FAQs: Your VFD Concerns
What IS VFD Full Form In HVAC?
VFD is an abbreviation of Variable Frequency Drivers. It is an electro-mechanical device
used to control the voltage and frequencies of Alternating Current (AC) coming from the
circuit and change into Direct Current (DC) and supply it to the motor.
What Is The Use Of VFD In HVAC Systems?
The VFD HVAC control system is a new and highly advantageous trend in the electrical,
or specifically the HVAC industry. It maintains the energy supply to the motor, fulfills its
power requirements, prolongs its life span, and saves it from fast deterioration.
Is Using VFD HVAC Compressor A Good Option?
Yes, absolutely. If your HVAC system’s compressors have VFD installed, then your
system’s efficiency will not only boost, but your compressor’s life span will also be
prolonged. Having a VFD installed in HVAC is quite beneficial.

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Final Thoughts
The positive aspects of using a VFD HVAC controller in your home, hospital, office,
school, restaurant, mall, and all kinds of buildings are limitless.
From controlling the current flow to reducing the power bills, one couldn’t enlist all of the
advantages of it.
However, the loud noise produced by the VFD in an HVAC system can be a disturbing
factor, but there are many practices to reduce them also.
And undoubtedly, the benefits you get from having a VFD in HVAC are much more than
bearing the noise.
We hope this article has cleared all your queries regarding the VFD HVAC controller and
its impact. If you still have any queries, drop them down in the comment section, and our
experts will answer them!