So you're planning your whole-house rainwater system. You know that pumps are integral to providing rainwater to end users that require pressurized flow. But you wonder... do I need a pressure tank?
Yes, but...
Why a pressure tank?
The pressure tank is an very important element of a water boosting pump. It serves 3 main functions:
- Limits the number of starts and stops on the pump, extending the life of the pump.
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Provides water under steady pressure for household fixtures.
- Provides a reserve supply of water for use when the pump is not running and/or during times of high demand.
But?
Water pumps have evolved, and Cactus Rain carries the latest technology of pumps that have this functionality built in!
Variable frequency drive (VFD) water pumps, also called constant pressure water systems, have a controller that determines the speed of the pump motor needed to maintain the pressure. When water is used, the pressure drops and the pump speeds up. When water use slows down or stops, the pressure increases and the pump slows down or stops. A near constant pressure is maintained. For most household use, a VFD-controlled water pump needs only a small pressure tank; usually 1 to 2 gallons, which is built in to these pumps!
The DAB E.sybox line of pumps can be used standalone without the need for a pressure tank - saving you money, maintenance, and space. The most advanced DAB technologies create constant pressure according to the system demands and thus an optimization of energy consumption.
They can also be used as a booster pump for systems with inadequate pressure, or in combination with a pressure tank to achieve pressurized reserve for when the pump is not running, or to meet peak demand during times of high demand without going to a bigger pump.
DAB VFDs from can save you maintenance, space, and energy! Learn more here: "Comparing DAB E.sybox and a small single-speed pump with pressure tank"
What size pressure tank?
Shortcut... One way to select the proper size for a pressure tank is to base it on the pump’s flow rate. For a typical private water supply pump that supplies water at a rate of 5 to 15 gallons per minute (gpm), multiply the flow rate by four to determine the size of a diaphragm or bladder tank. For example, a 9-gpm pump would require a 36-gallon storage tank.
This shortcut does not work for low-flow pumps (or low producing wells).
For those who want more math:
