HVACR216 - Hydronics

1. HVACR216 - Hydronics Circulator pumps

2. Circulator Pumps • The circulator pump is the heart of the Hydronic system • Although smaller and less expensive then the heat source, the pump is just as vital to a heating systems performance.

3. Circulator Pumps • Pumps come in a wide variety of designs, sizes and performance ranges. • In a closed loop, fluid filled hydronic system, the function of the pump is to circulate the fluid throughout the piping. • In a closed loop system the pump is made out of cast iron. (heating circuits) • In an open loop system the pump material is bronze. (potable water circuits)

4. Circulator Pumps Taco 006 bronze pump Taco 007 cast iron pump

5. Circulator Pumps • The type of pump used in hydronic systems is known as a centrifugal pump. • Most smaller circulator pumps utilize a permanent split capacitor (PSC) motor attached to an impeller. • As the impeller rotates, it adds mechanical energy (Head) to the fluid.

6. Circulator Pumps • As the impeller rotates, fluid within the center opening (the eye) of the impeller is rapidly accelerated through the passageways formed by the impeller vanes • As the fluid exits the impeller, the mechanical energy converts to a pressure increase.

7. Circulator Pumps • Most impellers are constructed of stainless steel, bronze or synthetic materials to prevent corrosion.

8. Circulator Pumps • Impeller

9. Circulator Pumps • A circulator pump doesincrease pressure at its outlet. • A circulator pump does not create a suction at its inlet. • All circulators require the entering water to be pushed into the inlet port of the pump by the system pressure upstream.

10. Circulator Pumps • The chamber surrounding the impeller is called the Volute. • Circulator pumps can be built with different shaped volutes. • The volutes shape determines how the pump will be installed on the system piping.

11. Circulator Pumps • VoluteMotor

12. Circulator Pumps • Inline type circulators have their inlet and discharge ports along a common centerline. • The inline type circulator is by far the most common type used in residential and light commercial hydronic systems.

13. Circulator Pumps • Inline Circulator

14. Circulator Pumps • By modifying the shape of the volute, a design called an end suction pump is created. • End suction pumps create a 90 degree turn in the system piping. • End suction pumps are usually floor mounted and are more common in larger hydronic systems.

15. Circulator Pumps • End suction pump

16. Circulator Pumps • End suction volute

17. Circulator Pumps • The modern, smaller circulator pump is known as a wet-rotor circulator. • The rotor, shaft and impeller are combined in a single assembly and housed in a chamber filled with the system fluid. • The motor is cooled and lubricated by the systems fluid.

18. Circulator Pumps • Wet rotor circulator

19. Circulator Pumps • The wet rotor circulator does not require oiling. • There is no leakage from worn seals. • They are small in size which makes it easy to locate and support. • They are relatively inexpensive.

20. Circulator Pumps • Another common pump design is the three piece circulator. • It consists of pump body (Volute), coupling assembly and a motor assembly.

21. Circulator Pumps • Three piece circulator Pump body Coupling assembly Motor

22. Circulator Pumps • Unlike wet rotor circulators, the motor of a three piece circulator is totally separate from the wetted portion. • This allows the motor or coupling to be serviced or replaced without the need to open the system piping.

23. Circulator Pumps • Most three piece circulators utilize a split phase motor. • The design of the coupling varies among manufacturer's. • A common design employs a spring assembly that absorbs vibration or high torque between the two shafts as the motor starts.

24. Circulator Pumps • Some of the disadvantages of using the three piece circulator are: • They are heavy and large • Must be oiled periodically • Noisier • Potential maintenance of seals and coupling • Motors are not as energy efficient

25. Circulator Pumps • Overview of circulators • All circulators have an arrow showing the direction of flow stamped on the Volute. • Most circulators should be installed with the shafts mounted in the horizontal position.

26. Circulator Pumps • The weight of the circulator should not be supported by the system piping unless it is relatively light and the piping itself is well supported. • All circulators should be installed with some sort of isolation valves to permit servicing.

27. Circulator Pumps • Always install the circulator so that its inlet is close to the connection point of the systems expansion tank. • Always install circulators to pump away from the point of no pressure change. • The point of no pressure change is the area near the expansion tank

28. Circulator Pumps • If mounting several circulators on one common header, support the added weight using rod, clamps, chain, etc. • If utilizing multiple circulators, you must also install check valves in each circuit.

29. Circulator Pumps • Circulators are available in multiple speeds. • Some circulators are available with internal flow checks. • Most currently produced wet rotor circulators are rated for continuous operation at fluid temperatures up to 230 degrees Fahrenheit.

30. Circulator Pumps • The 3 piece type circulator typically has maintenance issues that need to be addressed. • The seals will need to be replaced if leakage occurs. • The bearings needs to be oiled annually.