HVAC Pump Selection and Types

This article describes the minimum requirements for hydronic pumps for use with HVAC systems, including in line circulators, vertical in line pumps, end suction pumps and double suction pumps.

Pump Working Principle

A Pump is generally used to induce flow or raise the pressure of a liquid. Centrifugal pumps are a category of Dynamic pumps. The working principle of centrifugal pumps involves imparting energy to the liquid by means of a centrifugal force developed by the rotation of an impeller that has several blades or vanes.

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HVAC Pump Selection and Types

Submittals

Product data shall include certified performance curves and rated capacities; shipping, installed, and operating weights; furnished specialties; final impeller dimensions; and accessories for each type of product indicated. Pump’s operating point shall be indicated on curves.

Shop Drawings:

1. Pump layout and connections including setting drawings with templates for installing foundation and anchor bolts and other anchorages.
2. Wiring diagrams indicating power, signal and control wiring. Wiring diagrams shall differentiate between manufacturer installed and field installed wiring.

Operation, installation and maintenance data shall be submitted for pumps to including operation, installation and maintenance manuals.

Quality Assurance

• Pumps shall be fabricated and labeled to comply with UL 778 for construction requirements.
• Electrical components, devices, and accessories shall be listed and labeled as defined in NFPA 70, Article 100, by a testing agency acceptable to authorities having jurisdiction, and marked for intended us
• Pumps shall be installed in accordance with HI 1.1-5.

In Line Circulators 

• In line circulators shall be horizontal, in line, centrifugal, single stage, bronze fitted, radially split case design; rated for 860 kPa minimum working pressure and a continuous water temperature of 107° C.
• Casing shall be cast iron, with threaded companion flanges for piping connections, and threaded gage tappings at inlet and outlet connections. Connections may be different to suit project requirements.
• Impeller shall be ASTM B 36/B 36M, rolled temper brass fabrication, statically and dynamically balanced, closed, overhung, single suction, and keyed to shaft or ASTM B 584, cast bronze, statically and dynamically balanced, closed, overhung, single suction, and keyed to shaft.
• Shaft shall be steel with an oil lubricated copper sleeve.
• Seals shall be mechanical type, including carbon-steel rotating ring, stainless-steel spring, ceramic seat, and flexible bellows and gasket.
• Pump bearings shall be oil lubricated, bronze journal and thrust type.
• Motor bearings shall be oil lubricated, sleeve type.
• Couplings shall be flexible, capable of absorbing torsional vibration and shaft misalignment.
• Motor shall be resiliently mounted to pump casing.

  

Compact Inline Circulators Requirements in HVAC System

• Compact inline circulators shall be water cooled or cartridge type, horizontal, in line, compact design, seal less, centrifugal, and single stage.
• Water cooled circulator shall include pump and motor assembled on a common shaft in hermetically sealed unit, without stuffing boxes or mechanical seals.
• Water cooled circulator shall include lubrication of sleeve bearing and cooling of motor by circulating pumped liquid through motor section, and isolation of motor section from motor-stator windings by corrosion resistant, nonmagnetic, alloy liner.
• Cartridge type circulators shall include pump and motor assembled on a common shaft in cartridge type, hermetically sealed unit, without stuffing boxes or mechanical seals.
• Cartridge type circulators shall include isolation of motor section from motor stator windings by corrosion resistant, nonmagnetic, alloy liner.
• Circulators shall be design rated for 860 kPa minimum working pressure and a continuous water temperature of 107° C.
• Casing shall be cast bronze or cast iron, with stainless steel liner, static O ring seal to separate motor section from motor stator, and flanged piping connections.
• Impeller shall be overhung, single suction, closed or open, and nonmetallic.
• Shafts shall be stainless steel with carbon steel sleeve.
• Motor shall be single or multi-stage.
• Vertical inline pumps shall be centrifugal, flexible-coupled, single-stage, radially split case design. Include vertical-mounting, bronze-fitted design and mechanical seals rated for 860 kPa minimum working pressure and a continuous water temperature of 107° C.
• Casing shall be cast iron, with threaded companion flanges for piping connections smaller than NPS.
• 3, drain plug at low point of volute, and threaded gage tappings at inlet and outlet connections.
• Impeller shall be ASTM B 584, cast bronze, statically and dynamically balanced, closed, overhung, single suction, and keyed to shaft.
• Wear rings shall be replaceable with bronze casing.
• Shaft shall be stainless steel with bronze sleeve for close coupled pumps or axially split spacer coupling for flexible coupled pumps.
• Seals shall be mechanical, with carbon steel rotating ring, stainless steel spring, ceramic seat, and flexible bellows and gasket or stuffing box, with at least four rings of graphite-impregnated braided yarn with bronze lantern ring between center two graphite rings, and bronze packing gl Manufacturer shall be consulted for other seal recommendations based on pump application.
• Motor shall be directly mounted to pump casing and with lifting and supporting lugs in top of motor enclosure.

Close Coupled End Suction Pumps Requirements in HVAC System

• Close coupled end suction pumps shall be centrifugal, single stage, bronze fitted, back pull out, radially split case design; rated for 1200 kPa minimum working pressure and a continuous water temperature of 107° C.
• Casing shall be cast iron, with flanged piping connections, drain plug at low point of volute, and threaded gage tappings at inlet and outlet connections. Unions shall be provided at connections for casings that are not available with threaded companion flanges.
• Impellers shall be ASTM B 584, cast bronze, statically and dynamically balanced, closed, overhung, single suction, keyed to shaft, and secured by locking cap screw.
• Wear rings shall be replaceable with bronze casing.
• Shaft shall be steel with bronze sleeve and neoprene slinger for flanged pumps or close coupled to motor shaft for threaded connection pumps.
• Seals shall be mechanical, with carbon steel rotating ring, stainless-steel spring, ceramic seat, and flexible bellows and gask Consult manufacturer for other seal recommendations based on pump application.
• Motor shall be directly mounted to pump casing and with supporting legs as integral part of motor enclosure.

  

  

How to read Name plate data of pumps and what information it gives.

Flexible Coupled End Suction Pumps Requirements in HVAC System

• Flexible coupled end suction pumps shall be base mounted, centrifugal, single stage, bronze fitted, back pull out, radially split case design; rated for 1200 kPa minimum working pressure and a continuous water temperature of 107° C.

• Casing shall be cast iron, with flanged piping connections, drain plug at low point of volute, threaded gage tappings at inlet and outlet connections, and integral feet or other means on volute to support weight of casing and attached piping. Casing shall allow removal and replacement of impeller without disconnecting piping.
• Impeller shall be ASTM B 584, cast bronze, statically and dynamically balanced, closed, overhung, single suction, keyed to shaft, and secured by locking cap screw.

• Wear rings shall be replaceable with bronze casing.
• Seals shall be mechanical, with carbon steel rotating ring, stainless steel spring, ceramic seat, and flexible bellows and gasket or stuffing box, with at least four rings of graphite-impregnated braided yarn with bronze lantern ring between center two graphite rings, and bronze packing gland. Manufacturer shall be consulted for other seal recommendations based on pump application.
• Coupling shall be one of the following based on application:

• • Flexible, capable of absorbing torsional vibration and shaft misalignment

• • Flexible spacer type, capable of absorbing torsional vibration and shaft misalignment; with flange and sleeve section that can be disassembled and removed without removing pump or motor

• • Flexible spacer type, capable of absorbing torsional vibration and shaft misalignment for motor sizes of 100 hp and smaller; with flange and sleeve section that can be disassembled and removed without removing pump or motor, for sizes larger than 100 hp.
  • Flexible spacer type, capable of absorbing torsional vibration and shaft misalignment; with flange and sleeve section that can be disassembled and removed without removing pump or motor.
• Coupling guard shall be steel, removable, and attached to mounting frame.
• Mounting frame shall be welded steel frame and cross members, factory fabricated from.
• ASTM A 36/A 36M channels and angles and fabricated for mounting pump casing, coupling guard, and motor. Motor mounting holes shall be field drilled for field installed motors.
• Motor shall be secured to mounting frame, with adjustable alignment.

  

Pump Specialty Fittings

Suction diffusers shall be angle or straight pattern, 1200 kPa pressure rating, cast iron body and end cap, pump inlet fitting; with bronze startup and bronze or stainless steel permanent strainers; bronze or stainless steel straightening vanes; drain plug; and factory or field fabricated support.

Triple duty valves shall be angle or straight pattern, 1200 kPa pressure rating, cast iron body, pump discharge fitting; with drain plug and bronze fitted shutoff, balancing, and check valve features.