It's a somewhat awkward coexistence between advancing technology and an industry that itself admits is slow to embrace change. But make no mistake -- variable speed constant pressure pumping systems are the wave of the future.
We canvassed the pump industry -- talking to contractors, consultants and manufacturers -- to discuss the latest technological trends, and the main -- and often only -- topic was indeed variable speed submersible pump systems. Several people were quick to mention that as far as domestic pumps are concerned, this constant pressure innovation is the first efficiency gain since the submersible pump was perfected back in the 1950s.
What's to LikeThe original intent -- providing city-like water pressure to private water well systems -- is just the beginning. These pumps are designed to vary the speed of the pump motor. When more water is needed, it runs faster; when less water is needed, it can relax and run slower. And there are considerable energy savings at the lower rpms. For example - a small subdivision was running a consistent 5hp load 24 hours a day, seven days a week, 365 days a year. That was costing them about $150 per month. They had a 10-horse submersible that went on and off to fill the storage tank. It was common for them to have a $300 electric bill every month. Since they converted that 5-horse to a variable frequency drive, the power bill dropped in half. The conversion will be paid for in short order and the water pressure is improved as well - whether two houses or 10 houses are running their sprinklers. And they've had no maintenance.
Another benefit of the pump being able to run more slowly is less wear and tear on the motor. Use your car as an analogy. If you start it up, race down a city block and then shut if off, start it up again, fly down another block and shut it down É Do that for a few hundred miles -- it just tears up the equipment. The same thing happens to an electric motor. By using only the power needed, the variable speed pumps eliminate a lot of that abuse.
Homeowners also appreciate the quiet operation and the space-saving 2-gallon pressure tanks. And of no small consequence is the cost of power these days; being able to help them on that front really gets a homeowner's attention.
For contractors, it's all about efficiency and productivity. You want the installation to go smoothly and you don't want callbacks. These new systems include things that previously had to be installed piece-by-piece. You'd have to put in things like low water protection and voltage spike protection; that's now included in these pumps, and quality control is taken care of at the factory. One thing the variable speed pumps basically have done away with is the pressure switch. What you have is a computerized controller that has no moving parts. You can tell it what pressure you want it to operate at, and it will vary the pump's rpms in order to maintain that pressure. It doesn't matter if someone is using one faucet or 10 lawn sprinklers, the pump will ramp that thing up to where it will hold the constant pressure.
The variable speed pumps, instead of going from zero to 3450 rpms in less than a second, ramp up more gradually. It warms up to the task, and you avoid the shock of that start-up torque. You can set limits of 4,000 rpm at the high end and 1,000 rpm at the low end. You can couple these things in parallel. If one pump and motor can maintain the desired pressure, it will do it. But if you exceed the parameters of the first pump, it will start the second pump and the two will run at whatever rpm it takes to hold the pressure.
What's the Holdup?Drillers are famous for not wanting to change their ways. Add to that a higher initial cost and the fact that there were some problems with these systems in the very beginning, and you're talking about some rather hesitant drillers. Some of the early reports were not terribly favorable, and contractors are rightly concerned about their reputations. Was all the R&D conducted properly? How will the pumps that work so well in a laboratory environment perform in the real world? These are important concerns to drilling contractors, many of whom are content with the way things were, and are rather patient when it comes to new ideas in the marketplace.
Also, because they rely on computer electronics, they will store some sort of a charge. So from a service standpoint, you want to be a little extra careful when you start sticking your fingers in there. There's a potential for several hundred volts stored up on capacitors. It's made very clear on the instructions - wait at least 15 minutes after shutdown to make sure the power is off of it before going in to do diagnostic work.
It's the FutureIn the works for these pumps: infrared controllers that you'll be able to dial into to see how the pump is running -- with information on amperage, rpms, etc. You'll be able to do a diagnostic check without having to go out to the site. And already, if for some reason the computer processor goes down, you can switch it to run as a full-speed motor without the processor. It will stand alone and work like any other pump with a pressure switch and the rest of it.
Manufacturers constantly work on improving the efficiency and productivity of their equipment. Downthrust protection is an example. And they are trying to get submersibles to be able to pump more solids and sand to reduce wear and tear and clogging.
After a bumpy start, the kinks are getting worked out. This is where the industry is headed.
One drilling contractor told us that he reluctantly got involved with the variable speed submersible pumps because he was getting into factory applications where they demanded the constant pressure. He initially was hesitant, but that's what his customer wanted, so he acquiesced. He says that at first there was a lot of troubleshooting but the system is running great now. His customer couldn't be happier.
So right now, it's almost as if the consumers are driving this trend. And that will accelerate. People are increasingly becoming better educated consumers (the Internet being largely responsible for that); they've done their homework and know what they want.
This customer demand, coupled with increased positive experience in the field, will make the switch to variable speed submersible pump systems happen sooner rather than later. Get comfortable with this trend and act accordingly for the benefit of your business.