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HVACR115 – Mechanical for Gas Heat

HVACR115 – Mechanical for Gas Heat

Blower AssembliesBlower Assemblies

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Blower AssembliesBlower Assemblies

• Are constructed to pull air through the return air ducts and filter, then push air through the heat exchanger and supply ducts.

• They require careful adjustment to produce enough volume and velocity to maintain comfort at design conditions.

• Are constructed to pull air through the return air ducts and filter, then push air through the heat exchanger and supply ducts.

• They require careful adjustment to produce enough volume and velocity to maintain comfort at design conditions.

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Blower AssembliesBlower Assemblies

• There are two types of blower assemblies available:– Direct Drive– Belt Drive

• There are two types of blower assemblies available:– Direct Drive– Belt Drive

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Direct DriveDirect Drive

• Approximately 1050 RPM on high speed.

• Motor is attached by either the blower wheel hub assembly on the shaft or through a spider coupling.

• Supported by motor shaft.

• Variable speed requires a multi-speed motor.

• Used in residential applications mainly.

• Approximately 1050 RPM on high speed.

• Motor is attached by either the blower wheel hub assembly on the shaft or through a spider coupling.

• Supported by motor shaft.

• Variable speed requires a multi-speed motor.

• Used in residential applications mainly.

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Spider CouplingSpider Coupling

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Belt DriveBelt Drive

• Motor is usually at 1725 RPM.

• Blower wheel is supported by the shaft and bearings.

• Variable speed is obtained by varying the setting of a split pulley.

• More often used on light commercial applications.

• Motor is usually at 1725 RPM.

• Blower wheel is supported by the shaft and bearings.

• Variable speed is obtained by varying the setting of a split pulley.

• More often used on light commercial applications.

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Adjustable PulliesAdjustable Pullies

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Blower AssembliesBlower Assemblies

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Belt Drive BlowersBelt Drive Blowers

• It is important that the drive on the motor and the pulley on the blower wheel be perfectly aligned.

• Any belt wear, more than normal, is most often attributed to the improper alignment of the pulley and motor.

• It is important that the drive on the motor and the pulley on the blower wheel be perfectly aligned.

• Any belt wear, more than normal, is most often attributed to the improper alignment of the pulley and motor.

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ECM and VFD MotorsECM and VFD Motors

• Today more and more manufacturers are using ECM and VFD motors to control air volume.

• Speed of the motor is directly linked to application and volume demand.

• Can compensate for air blockages.

• Today more and more manufacturers are using ECM and VFD motors to control air volume.

• Speed of the motor is directly linked to application and volume demand.

• Can compensate for air blockages.

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VFD MotorsVFD Motors

• VFD – Variable Frequency Drive remember what determines the speed of an electric motor

• Frequency of motor and the number of field poles. Rpm = (fr x 120)/NP

• If you drop the frequency you slow down the motor. i.e. a 1050 rpm motor with 30htz instead of 60htz spins at appr.600 rpms.

• If you drop the speed you drop the volume of air delivered.

• VFD – Variable Frequency Drive remember what determines the speed of an electric motor

• Frequency of motor and the number of field poles. Rpm = (fr x 120)/NP

• If you drop the frequency you slow down the motor. i.e. a 1050 rpm motor with 30htz instead of 60htz spins at appr.600 rpms.

• If you drop the speed you drop the volume of air delivered.

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ECM MotorsECM Motors

• ECM – Electronically Commutated Motors.

• The motors speed is controlled by inverting the voltage from AC to DC and then sent to the motor at the amount needed for whatever speed is needed.

• ECM – Electronically Commutated Motors.

• The motors speed is controlled by inverting the voltage from AC to DC and then sent to the motor at the amount needed for whatever speed is needed.