ClassX Video Lessons Youtube Channel The Engineering Mindset Circulating Pump Basics – How a pump works HVAC heating pump working principle
Welcome to an exploration of circulating pumps, a crucial component in HVAC systems. These pumps play a vital role in ensuring efficient water circulation in heating systems. Let’s dive into the mechanics of how they operate and their applications.
Circulating pumps are inline centrifugal pumps, characterized by their aligned inlet and outlet. They utilize centrifugal forces to move water, making them essential in systems where quick access to hot water is needed. These pumps are commonly used in hydronic heating systems to circulate hot water between boilers and radiators or other heat exchangers. They also help distribute heat to various zones within large buildings.
The circulating pump comprises two main parts: the pump and the motor. The motor is an induction type, converting electrical energy into mechanical energy to drive the pump. The pump casing features an inlet and an outlet, with an arrow indicating the flow direction. Water enters through the inlet, moves through the pump, and exits via the outlet.
Within the pump casing, water enters through the eye of the impeller, a rotating component that imparts centrifugal force on the water. The impeller is surrounded by a volute channel, which collects water and directs it to the outlet. The back plate behind the impeller ensures water remains within the casing and supports the shaft’s smooth rotation.
The motor consists of copper wire coils packed into the stator, which remains stationary. Electricity flowing through these coils creates a rotating electromagnetic field, causing the rotor to spin. The rotor, connected to the shaft, drives the impeller, moving water through the pump. The motor housing protects the stator and coils, with a terminal box for electrical connections and a speed selector switch to adjust the motor’s rotational speed.
The circulating pump uses a single-phase alternating current induction motor. Alternating current (AC) is the standard electrical supply in homes and workplaces, where electrons alternate direction. As electricity flows through a wire, it generates an electromagnetic field. Wrapping the wire into a coil strengthens this field, and applying AC causes the magnetic field to expand and collapse, enabling rotation.
A capacitor in the pump creates a second phase, essential for generating a rotating magnetic field. A second coil, positioned 90 degrees from the first, is connected in parallel with a capacitor in series. The capacitor stores and releases electrons, facilitating the creation of the rotating field necessary for the rotor’s movement.
Water enters the pump through the inlet and the impeller’s eye. The motor’s electrical flow, aided by the capacitor, creates a rotating magnetic field, spinning the rotor. The rotor’s movement drives the impeller, imparting kinetic energy to the water. As water reaches the impeller’s edge, it gains high velocity, flowing into the volute where velocity converts to pressure. This pressure difference between the outlet and inlet ensures water circulates through the system efficiently.
In summary, circulating pumps are integral to HVAC systems, providing efficient water circulation and heat distribution. Understanding their components and operation enhances our appreciation of their role in maintaining comfortable indoor environments.
For further learning, explore additional resources and stay connected with The Engineering Mindset on social media platforms.
Create a detailed diagram of a circulating pump, labeling each component such as the impeller, motor, and capacitor. Use online tools like Lucidchart or draw.io to make your diagram interactive. Share your diagram with classmates and explain how each part contributes to the pump’s operation.
Form small groups and discuss the role of circulating pumps in HVAC systems. Each group should focus on a specific aspect, such as the electrical components or the mechanical operation. Prepare a short presentation to share your findings with the class, highlighting the importance of each component.
Participate in a lab session where you can disassemble a model circulating pump. Identify and examine each component, such as the impeller and motor. Reassemble the pump and test its operation, observing how changes in speed affect water circulation.
Analyze a case study of a building’s HVAC system that utilizes circulating pumps. Identify how the pumps are integrated into the system and discuss their impact on energy efficiency and heat distribution. Write a report summarizing your analysis and suggest potential improvements.
Use simulation software like ANSYS or SolidWorks to model the flow of water through a circulating pump. Experiment with different variables such as impeller speed and water pressure. Document your findings and discuss how these variables affect the pump’s efficiency and performance.
Sure! Here’s a sanitized version of the YouTube transcript:
—
Hello everyone, Paul here from The Engineering Mindset. In this video, we’re going to explore the typical circulation pump to understand the basics of how it works and where we use them. After this video, check out State Supply, who have kindly sponsored this content. You can find available circulating pumps, shop for parts, or speak to knowledgeable product specialists about top pump brands such as Bell & Gossett and Taco. Simply click the link in the video description below to learn more.
Circulating pumps come in various shapes, colors, and sizes, but they typically look something like these. These pumps are inline centrifugal type pumps, meaning their inlet and outlet are aligned, and they move water using centrifugal forces. We commonly use these pumps to circulate hot water around a heating circuit, so when we open a tap, we have almost instant access to hot water. Otherwise, we would have to wait for hot water to flow through the entire system. In hydronic heating systems, we also find these pumps circulating heated water between the boiler and radiators or other types of heat exchangers. Additionally, circulating pumps are used in larger heating systems to supply heat to different parts or zones within a building.
The circulating pump consists of two main parts: the pump and the motor. The motor is an induction type, which converts electrical energy into mechanical energy. This mechanical energy drives the pump and moves the water. The pump casing has an inlet and an outlet; the pump pulls water in through the inlet and pushes it out through the outlet. Typically, there will be an arrow on the casing to indicate the direction of flow.
As this is an inline pump, the inlet and outlet are aligned concentrically. This design allows us to cut a section of pipe out from a hot water system and install a circulating pump in that space without altering the existing pipework. The water needs to enter the pump through the eye of the impeller, which is achieved by the curved path of the inlet that sweeps around into the impeller.
Inside the pump casing, there is a channel known as the volute. After the water exits the impeller, it collects in this channel and makes its way to the outlet. The impeller, which sits within the pump casing and is surrounded by the volute channel, rotates and imparts centrifugal force on the water, pushing it out of the pump and through the pipes.
Behind the impeller is the back plate, which acts as a barrier to keep the water flow within the pump casing. The back plate also holds one of the bearings for the shaft to ensure smooth rotation. Attached to this is a rubber seal to prevent leaks.
Next, we find the shaft and the rotor. The rotor is attached to the shaft, which connects to the motor. When the rotor rotates, so does the shaft and the impeller, driving the water within the pump. The rotor sits within the rotor can, which provides a physical barrier to prevent water from contacting the electrical circuit of the induction motor.
The induction motor consists of coils of copper wire tightly packed into the stator. The coils and the stator are stationary and do not rotate. Electricity flows through the coils, creating a rotating electromagnetic field that causes the rotor to spin. The motor housing protects the stator and coils, and on the side, you will find the electrical terminal box. On the front of this box is the speed selector switch, which allows us to manually change the rotational speed of the motor between low, medium, and high settings, thus changing the flow rate of the pump.
Inside the terminal box, we have the speed selector switch, ground, neutral, and line terminals for connecting the pump to a power supply. There is usually also a capacitor inside this type of pump, which is vital for its operation.
The electrical motor in the circulating pump is a single-phase alternating current induction motor. Electricity is the flow of electrons through a wire. We have direct current (DC) from sources like batteries, where electrons flow in one direction. However, the electrical supplies in homes and workplaces are alternating current (AC), where electrons alternate direction repeatedly.
As electricity flows through a wire, it generates an electromagnetic field. By wrapping the wire into a coil, we create a stronger electromagnetic field. When we apply alternating current to the inductor, the magnetic field expands and collapses, reversing the north and south poles of the coil. This expanding and collapsing magnetic field is necessary for rotation.
In the circulating pump, we use a capacitor to create a second phase. A second coil is inserted into the stator, 90 degrees from the first coil. The two coils are wired in parallel, but the second coil has a capacitor connected in series. The capacitor stores electrons when the electricity moves in one direction and releases them when the supply reverses, allowing for the creation of a rotating magnetic field.
Typically, there is a switch on the side of the motor terminal to change the speed of the motor and the pump flow rate. The run coil has various connection points, and the switch connects to these different points to change the length of the coil that electricity passes through.
When we pass an alternating current through an inductor, the magnetic field interferes with the electrons trying to flow through it, a phenomenon known as inductive reactance. When we increase the length of the coil, the inductive reactance increases, making it harder for the current to flow. This reduces the speed and torque of the motor.
So, how does the circulating pump work? Water enters the pump through the inlet and the eye of the impeller. The electricity flows through the motor windings, and the capacitor helps create a rotating magnetic field, forcing the rotor to spin. The shaft connects the rotor to the impeller, and as the impeller rotates, it imparts kinetic energy to the water, moving it outwards.
By the time the water reaches the edge of the impeller, it has a high velocity. This high-speed water flows off the impeller and into the volute, where it hits the wall of the pump casing. This impact converts velocity into potential energy or pressure. As the water moves outwards, it creates a region of low pressure at the center, pulling more water in and developing flow.
The volute channel has an expanding diameter, which decreases the velocity of the water and increases the pressure. The discharge outlet, therefore, has a higher pressure than the suction inlet, allowing us to force water to circulate through the pipework as needed.
That’s it for this video! To continue learning, check out one of the videos on screen now, and I’ll catch you in the next lesson. Don’t forget to follow us on Facebook, Instagram, LinkedIn, and Twitter, as well as visit The Engineering Mindset.
—
This version removes any informal language and maintains a professional tone while preserving the essential information.
Circulating – Moving continuously or freely through a closed system or area. – In a heat exchanger, the circulating fluid transfers thermal energy between the hot and cold sides.
Pumps – Devices used to move fluids or gases by mechanical action. – Engineers designed the pumps to efficiently transfer water from the reservoir to the treatment plant.
Motor – A machine that converts electrical energy into mechanical energy to perform work. – The electric motor drives the conveyor belt, ensuring smooth operation in the assembly line.
Impeller – A rotating component of a pump or compressor that transfers energy from the motor to the fluid. – The impeller’s design is crucial for maximizing the pump’s efficiency and flow rate.
Centrifugal – Relating to the force that moves objects away from the center of rotation. – Centrifugal pumps are commonly used in industrial applications due to their ability to handle large volumes of fluid.
Energy – The capacity to do work or produce change, often measured in joules or kilowatt-hours. – Understanding energy conservation is fundamental in designing sustainable engineering systems.
Electrical – Relating to electricity, a form of energy resulting from the existence of charged particles. – Electrical engineers focus on the generation, distribution, and utilization of electrical power.
Capacitor – An electrical component used to store and release energy in the form of an electric field. – Capacitors are essential in electronic circuits for filtering and energy storage applications.
Velocity – The speed of something in a given direction, often used in fluid dynamics and mechanics. – Calculating the velocity of fluid flow is critical in designing efficient piping systems.
Pressure – The force exerted per unit area, often measured in pascals or psi. – Engineers must consider pressure changes in pipelines to prevent leaks and ensure safety.
