A.Y. McDonald DuraMAC Light Commercial Booster Pump

The DuraMAC Light Commercial and Irrigation booster carries 35 GPM and up to 78 PSI of boost from an easy set-up installation, with a versatile control offering three modes of operation.

Stainless steel and no-lead brass construction throughout the waterway, with dry-run protection. Electronics are separated and sealed from the waterway for safety and ease of field repair.

Typical applications: small commercial buildings, irrigation zones, larger homes and multi-bath residences, and tank-fed supply where 20 GPM is not enough.

Each Light Commercial is a complete single unit. When a building needs more than 35 GPM, the Dual-Mode family carries it on the same no-lead brass and stainless waterway: the Dual-Mode Simplex carries 70 GPM on one pump, and the Dual-Mode Duplex stages two pumps to 120 GPM with lead/lag control and full redundancy.

Multi-pump staging is offered in the Dual-Mode family.

The figures below are the pressure this pump adds. That is what a pump curve measures — the impeller does not know what pressure is already on its inlet.

Models

Source: Baker Water Systems DuraMAC Booster Pumps catalog, rev 3/26, p. 239. Weights as printed in the catalog. PRV: A.Y. McDonald recommends a pressure reducing valve above this incoming pressure, so total boosted pressure stays below 80 psi. Many plumbing codes do not recommend system pressure above 80 psi; check local code.

Pressure added in PSI

Drawing from a tank or cistern — nothing arrives with pressure, so what the pump adds is what you get. Read the table straight through: the 78 PSI model delivers about 25 GPM at 48 psi.

Fed by a city main — this is a single-speed pump, so the boost arrives on top of whatever the main already delivers. A.Y. McDonald sizes it as arithmetic: 30 psi incoming plus the 40 PSI model gives 70 psi total. The catalog advises against exceeding 80 psi total boosted pressure, which is why the 78 PSI model is listed for use with a holding tank above 2 psi incoming rather than on a live main.

Best operating range: 15 to 28 GPM. Below this range the pump recirculates internally, which causes vibration and premature seal wear. Above it, it cavitates and the motor draws past its rating. Most booster failures are pumps that were oversized for the building.

Zero flow is the shut-off point — a ceiling, not a working point. The table ends at the published maximum, 35 GPM. Figures are 60 Hz US data at full speed, digitized from the published curve in the Baker Water Systems DuraMAC Booster Pumps catalog, rev 3/26, p. 239, and rounded down. Best operating range is derived from the published curve; A.Y. McDonald publishes no efficiency curve for these models. Points at 5 GPM are left out to keep the table readable; the full curve is in the image gallery. Feet of head = PSI × 2.31.

Pressure Mode — starts on pressure drop, stops on low flow. Appropriate for the majority of light commercial and residential applications. The pump runs continuously while there is a need for water.

Flow Mode — starts on water flow, stops on low flow. For systems where pressure fluctuates or occasional leaks are present. The pump runs when water use exceeds approximately one gallon per minute.

Conservation Mode — starts on pressure drop, stops on low flow. For systems where incoming pressure is adequate for most uses and boosting is only needed at peak demand, such as multiple showers, bathtubs or irrigation zones running together. The pump runs only when system pressure is below the city supply pressure.

Parts in contact with the water, per the Baker Water Systems DuraMAC Booster Pumps catalog, rev 3/26.

Seals, impellers, controls and other service parts for this pump are listed on DuraMAC Booster Pump Parts — 35 GPM Light Commercial, by part number.