A.Y. McDonald Variable Speed Constant Pressure Booster Pump

The Variable Speed Booster — Baker Water Systems calls it VS Booster — is the new-generation constant pressure booster from A.Y. McDonald and Baker. Its built-in inverter holds a constant discharge pressure by varying pump speed instead of cycling on and off, using very little energy and removing the pressure swing a fixed-speed pump gives between cut-in and cut-out.

It keeps the traditional pump configuration in an ultra-compact body — the variable frequency drive, the pressure tank, the discharge pressure sensor and a suction-side check valve are all built in, so the installation is plug and play. The intuitive digital keypad programs it in a few steps, and Baker advertises app-based monitoring and programming.

Protection: dry-run protection, detection of air in the pump casing, small-leakage detection and overload protection.

The Variable Speed Booster is a complete single unit, sized for the building it serves. Where a building needs more water than one unit carries, the Dual-Mode family stages pumps to do it: the Dual-Mode Simplex carries 70 GPM, and the Dual-Mode Duplex stages two pumps to 120 GPM with lead/lag control.

The figures below are the pressure this pump adds at full speed. That is what a pump curve measures — the impeller does not know what pressure is already on its inlet. The drive holds lower pressures by running the pump slower, so the curve is the ceiling at each flow rather than what you will see at a 50 psi setting.

Models

Source: Baker Water Systems VS Booster Constant Pressure Boosting System brochure, technical data and dimensions and weights tables.

Pressure added in PSI

Drawing from a tank, cistern or well — nothing arrives with pressure, so what the pump adds is what you get. Set to 50 psi, the 1 HP model holds that setting out to about 10 GPM and the 2 HP out to about 20 GPM.

Fed by a city main — the pump adds on top of what already arrives, but the drive will not hold more than 65 psi in total. On a 40 psi main set to 60 psi, the pump only has to add 20 psi, and at that much added pressure it delivers well beyond what it gives from a tank. Incoming pressure turns into extra flow at the same set point.

Best operating range: 6 to 18 GPM on the 1 HP model, 10 to 34 GPM on the 2 HP. This is where the pump turns the most electricity into water pressure. Ask for more flow than it can deliver at your setting and it runs at full speed continuously, which is where motors and seals wear out. Sizing a booster to the building rather than to the headline numbers is what makes it last.

Zero flow is the shut-off point — a ceiling, not a working point. Figures are at full speed, read from the published curves in the Baker Water Systems VS Booster brochure (plotted in ft of head) and rounded down; the 25, 50 and 65 psi set-point lines printed on the curves anchor the readings, including the 50 psi duty points of 10 GPM (1 HP) and 20 GPM (2 HP). Best operating range is the shaded band on those curves. Bold = the last point on that model’s curve, its max flow; — = beyond it. Points at 2, 4, 5, 6, 14, 15, 18, 25 GPM are left out to keep the table readable; the full curve is in the image gallery. Feet of head = PSI × 2.31.

Components, per the Baker Water Systems VS Booster brochure.

Service parts for the Variable Speed Booster are supplied on request — email sales@watermainsupply.com with the model and part number from the nameplate.

A.Y. McDonald advertises app-based monitoring and programming for the Variable Speed Booster alongside the on-board digital keypad. The pump is fully programmable from the keypad without it. Call 1-888.510.4036 and we will confirm the current app and the module your unit needs.