BOOSTERS, BACKFLOW, AND LEGIONELLA SERIES
1) Eliminate the PLC
Decades ago, the Programmable Logic Controller (PLC) was introduced to alternate and control constant speed pumps. Then some genius electrical engineers invented VFD’s (variable frequency drives), which revolutionized the booster pump industry.
Despite the fact that most water booster pump systems today are still supplied with a PLC, most VFD’s can be networked together which eliminates the requirement for a PLC.
This was best summed up in a 2013 article by Steve Petersen, Yaskawa Drives, Pump Protection Made Easy: “For some unbeknownst reason, engineers and technicians in the motor control industry associate a PLC as being a necessary component for VFD control. This may have rung true years ago, but VFD technology has progressed and made technological leaps and bounds just as much as other technologies in recent years.
VFD’s have reached the maturity level that eliminates the need to install and program a PLC which was previously needed to make many applications function.”
2) Eliminate the UL508 Panel
The UL508 Panel was originally designed to house all of the random pump controls, including pressure switches, alternating switches, timers, low & high pressure switches, transformers, gauges, etc.
Like the ole PLC, the functions and design of the VFD’s have eliminated the need for an expensive panel.
3) Use ASME Tanks sparingly
ASME tanks are intended for higher pressure systems, typically above 100psi. Because they’re 5X more expensive than non-ASME tank, a lot of money can be saved here. Some municipalities insist on ASME tanks, but there is little in the guidance documents requiring clients to spend ridiculous money on an unnecessary tank.
4) And then Down-Size the tank
Huge tanks were used on the ole constant-speed systems to minimize short-cycling. Because the VFD-controlled water booster pump system ramps down the pump’s speed, a small tank is adequate. And in large multi-family buildings, a tank isn’t necessary. And some engineers won’t spec any tank on an ASHRAE 188 facility.
5) Down-size the Horsepower
Often a smaller horsepower, less expensive triplex will deliver the same performance as a more expensive, high horsepower (Hp) duplex. For example, we regularly substitute 2Hp triplexes for 5Hp duplexes, as they’re less expensive to purchase, less expensive to maintain, and more energy efficient.
6) Simplex vs. Duplex
The redundancy of a duplex is great; but sometimes you just don’t need it.
- Example 1: Top floor of a small motel/hotel has 30psi without a pump. Many clients will opt to save money with a simplex, knowing that if the pump fails, there’s still adequate pressure for fixtures.
- Example 2: A condo complex has ten buildings, each needing a booster. Instead of ten duplexes, each building installs a simplex, and an 11th booster is purchased “for the shelf”.