Davey DD Series Constant Pressure Booster

DynaDrive puts the pump, the controller and the pressure tank into one compact assembly and holds a constant pressure across the flow range instead of cycling. The pump is a horizontal multistage centrifugal with every hydraulic part in stainless steel, impellers mounted directly on an extended motor shaft, and thick self-centering impeller neck rings.

Davey specifies it for household and domestic supply, farming and agricultural water systems, irrigation and turf watering, and automatic general water transfer. It leaves the factory set to 60 psi and is adjustable from the controller to a maximum of 87 psi.

The DD60-10NPT and DD90-11NPT add an air purging valve and stage porting, which Davey publishes as giving easier priming and less susceptibility to air leaks. Their casing assembly attaches to the motor bracket at eight points with an o-ring seal; the DD15-35NPT uses six.

The controller is capable of daisy-chain applications of two pumps in parallel. A second DynaDrive doubles the water available at the same pressure and gives the installation a spare machine.

Two pumps also hold more pressure at the flow the building actually draws. Each carries half the water, so each sits higher on its own curve: 24 gpm from a single DD90-11NPT comes out at 43 psi, while the same 24 gpm split between a pair is 12 gpm each and comes out nearer 68 psi. The one figure that does not rise is the maximum head at zero flow, fixed by the pump at 80 psi.

Two-pump figures are read from the published single-pump curve at the flow each pump carries. Davey publishes no combined performance table for daisy-chained DynaDrive.

Davey publishes DynaDrive as flow at stated pressures, so this is the manufacturer’s own table rather than a reading off a plot. The pressure figures are what the system holds at that flow.

Pressure added at flow, from the Davey DynaDrive curves:

DD15-35NPT — 65 psi maximum boost

DD60-10NPT — 91 psi maximum boost

DD90-11NPT — 80 psi maximum boost

Drawing from a tank or cistern — nothing arrives with pressure, so what the pump makes is what you get. Read the table straight through: a DD90-11NPT holds 43 psi at 24 gpm.

Fed by a city main — the drive holds the pressure you set it to, up to 87 psi, and only works as hard as it has to. Where the main already delivers part of what you need, the same pump reaches that setting at a higher flow. Incoming pressure buys you more flow, not more pressure.

Best operating range: 8 to 14 gpm on the DD15-35NPT, 11 to 19 gpm on the DD60-10NPT and 18 to 28 gpm on the DD90-11NPT. 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 maximum head — a ceiling, not a working point. Flow-at-pressure figures are tabulated by Davey in datasheet DWP1940-6/0625 and are reproduced here unchanged; best operating range is derived from those points, as Davey publishes no efficiency curve for this series. Note that the maximum set pressure is 87 psi on all three models, while the maximum head the pump can make differs by model — on the DD15-35NPT the 65 psi head is the real ceiling.

This system has no app or remote connectivity. It runs from the on-board controller, which shows warning indication for system faults, and needs no network connection.