Last month's column dealt with the low-water pressure problems faced by a large public park. New restrooms had been completed, but the installed plumbing fixtures with flush valves would not function properly. The engineers suggested relocating the Binford-2000 dual multi-horsepower energy-hungry booster pumps to the meter-pit area and house them in an above-grade structure. It's understandable and certainly desirable to want to reuse the existing and very expensive pressure-booster package: they are, after all is said and done, dealing with taxpayers' money.
However, you know who would be responsible if, for any reason, the relocated equipment caused any problems: You touch it — you own it! So, who needs to do the homework and crunch the numbers? We do — you and me, and that's how it works in the real world.
Step 1: They want to reuse the oversized booster rig — I think there's a much better system. The Internet provides rapid access to manufacturer's specifications and that provided the specifications for the existing booster pumps' flow rates. A call to their tech service group revealed we could lower the cut-off pressure-switch setting, but we'd be riding a knife-edge along its lowest limit. If the water level in the municipal water tank fell below 50-ft. above grade, the pumps would once again begin their extreme short cycling.
Step 2: Provide a solution that is much better. So much better, that it makes the old on/off booster pump technology look like an outdated muscle car! And, just like a muscle car, the WPG (watts per gallon electrical consumption) was lousy too. Variable-speed technology is sweeping through our plumbing and HVAC trades where motors are concerned and well-water pumps are no exception. We've installed Grundfos SQE variable-speed pumps for our residential customers, and they love the steady-state water pressure that can be easily dialed-in by the installer. You want 70 psi? No problem: set it and forget it. Mr. and Mrs. Customer will feel like they're connected to a municipal water system. No more complaints about waffling water pressure. That's great for a residential low-volume flow, but what about the potential flow rate when dealing with dozens of flush valves in a setting where large groups gather for family reunions and picnics?
The ideal solution would be an SQE in an in-line tube, and we considered making our own adaptation. Why not think of the incoming 4-in. PVC line as a well that can't run dry. It's connected to a gravity buffer tank that's open to atmosphere, and there's no chance of creating negative pressure in the incoming municipal line — a win for everyone. But, the folks at Grundfos had already designed what we needed!
The Grundfos EZ Boost system is an SQE style pump inside a stainless-steel tube that's a direct drop-in in-line booster pump with a variety of models to fit a wide range of variable GPM flow rates. It looked like a viable solution, but I was getting bogged down in the theoretical GPM peak-demand flow rates: from a 1.5 GPM faucet to more than 25 GPM if 1.0-gpf urinals and 1.6-gpf water closets were used near simultaneously. Hello Grundfos, can you help? After conferring with their technical service folks, who went way out of their way to help me select the best match, I had the information I needed to present a better solution to the York County Parks directors.
They wanted the York Water Company's blessing, and it was there that I ran into the toughest gauntlet in the sales process. No quick approval — they wanted to conduct their own investigation. After a few weeks, they agreed this was by far the best solution.
Full speed ahead? Not yet. There was, after all, almost three-quarters of a mile of 4-in. Schedule-80 PVC to consider from where the booster pump was to be installed and the second not-yet-built restrooms that would incorporate flush valves. That's 10.7-tons of water on the march at 70 psi! Slamming shut a flush valve with that much kinetic energy in motion was not something I wanted to have come back to bite me.
The solution was to give that water a soft landing — relocate the huge ASME expansion tank to the end-of-the-line restroom, which gave the customer an opportunity to recycle a portion of the Binford-2000 booster pump system. This has the added benefit of acting as a buffer-tank reservoir should there ever be a time when every single flush valve is flushed at the same time. The third and final benefit is giving the EZ Boost pump a longer and gentler run-time, which will result in better WPG mileage.
The engineers liked the idea of having the large ASME expansion tank at the end of the line. So much so that they required the Binford-2000 expansion tank be left inside the previously-built restrooms and incorporated a new one in the plans for the second set of restrooms that were recently completed.
The system works exactly as designed, and the Grundfos EZ Boost purrs like a kitten as it speeds up or slows down to meet flow demands.
All is well that ends well. The Binford-2000 muscle-bound booster pumps were relocated and used to feed a large above-grade atmospheric water tank in another York County Park where low water pressure had long been a problem.
Dave Yates owns F.W. Behler, a contracting company in York, Pa. He can be reached by phone at 717/843-4920 or by e-mail at [email protected].
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