In 1995 Southland Auto Wash increased drying horsepower at one of its busy sites from 100 to 195. At that time, we felt that there had to be a good way to reduce electrical consumption, or reduce the starting load these fans create.

We did extensive testing with an electrical engineer and realized that the fans on our blowers are not necessarily designed to produce maximum output at 60 Hz. Since all power in the US is delivered at 60 Hz., we studied both the use of a soft start and the use of a Variable Frequency Drive (VFD) instead of a typical motor starter.

Either of these devices can effectively reduce the incoming current rush and consequent spike which is not only very expensive electrically, but is also very damaging over time to the motor windings, the fan bearings, and the fan itself. So both a soft start and a VFD will reduce wear and increase life for all of these components, and will reduce the overall electrical consumption.

Many in the industry advocate a soft start with blast gates as the ideal way to operate a blower fan. While this setup does control start current, and can reduce the current between cars very effectively, it requires mechanical as well as electrical components. A properly sized and wired VFD is less expensive than a combined soft start and blast gates, in fact is not much more expensive than a simple soft start alone. The VFD provides the ability to control start current and avoid the inrush as well as the over torque of components, and in addition, it allows the operator to determine at what speed to run the dryers. The other devices do not provide this benefit.

Why is it beneficial to be able to control the speed of the fans? Because the typical fan is producing its full air flow at something less than 59 Hz. If you reduce the top current speed on a fan motor from 60 Hz to 59 Hz, there is a direct savings in electrical usage of 1/60th, times 3, because the motor is 3 phase. This correlates to an approximate 4% savings when running the dryers at top speed.

And as for the savings gained by reducing air flow and amp draw between cars, we simply turn the VFD “off” as soon as a car is complete at the fan, and today’s smart VFD uses “seek and spin” technology which “finds” the fan and speeds it back up when the next on signal is received. So using a VFD to reduce blow-out in open bed trucks, as well as to seasonally reduce overall electrical, is a matter of simple programming.

Choosing to run a slower fan speed for a cheaper wash has become popular where operators are finding that a $3 paying customer is not a profitable business opportunity. So to cut costs and reduce the expenses required to wash that $3 car, we’ve seen washes reduce their blower speed quite a bit, to the point where there is significant impact on the quality of drying.

While these type of decisions need to be individually tailored to the operation and its competitive situation, it is very easy with a VFD to select one or more preset speeds to provide “higher” or “lower” speed drying options, tailored to the wash type purchased. So perhaps a lower speed dry for a basic wash, and a higher speed dry for wash package upsells.

Total solutions for these and other electrical consumption questions are available through consultation with Xpert Solutions. We can tailor a Motor Control Center and Carwash Controller to meet the needs of an efficient user of electricity.

In addition to using VFD technology to reduce the wear, increase the life, and reduce the electrical cost of blower fan operation, we have developed methods and devices for controlling water and hydraulic pumps in a way that dramatically reduces heat build-up, energy waste, and pump wear and tear.