Greenheck Fan QEID Belt Drive versus Direct Drive, Belt Drive Advantages, Direct Drive Advantages

Belt Drive versus Direct Drive

Belt Drive Advantages

•Lower sound levels

•Motor out of the airstream for easy access

•Motor size may be changed to accommodate possible future air capacity requirements

•Final system balancing accomplished by changing drives

Direct Drive Advantages

• Fewer wear components and less maintenance, no shaft, bearings, pulleys, or belts

• More compact than equivalent belt drive size

• Motor in airstream for increased motor efficiency and cooling

• Equal loading between mounting brackets

• Final system balancing accomplished by adjusting the motor speed (ex. variable frequency drive use).

High Efficiencies = Lower Operating Costs

Example of Annual Operating Cost Savings

For a system performance requirement of 25,000 cfm at 2.5 inches of static pressure (wg) the corresponding operating power requirements are 13.97 Bhp with a QEI-I size 36 and 19.8 Bhp for a size 36 tubular centrifugal fan.

Formulas:

-Kilowatt-Hours = (Operating Power (Bhp) x 0.746 x Hours of Operation) / Motor Efficiency

-Operating Cost = Kilowatt-Hours x Power Cost per kW hour

Assumptions:

-Cost of electricity is $0.09 per kilowatt hour

-3,120 annual hours of operation (12 hours per day, five days a week, 52 weeks a year)

-93.0% motor efficiency (equal to NEMA Premium minimum efficiency for 15 and 20 hp, ODP, 1725 rpm motor)

Tubular Centrifugal Fan	QEI-I - Mixed Flow Fan
kW-Hours = (19.8 Bhp x 0.746 x 3120) / 0.93 = 49,554	kW-Hours = (13.97 Bhp x 0.746 x 3120) / 0.93 = 34,963
Operating Cost = 49,554 x $0.09 = $4,460	Operating Cost = 34,963 x $0.09 = $3,147

Annual Operating Cost Savings = $4,460 - $3,147 = $1,313

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