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Dual Flush

Client: Sloan Valve
  • Technology Development
  • System Architecture
  • Mechanical Engineering
  • Electrical Engineering
  • Software Engineering
  • Design for Manufacturing

An automatic, water-conserving and power-conserving dual-flush mechanism that easily attaches to a standard flush valve on commercial toilets.



Sloan Valve Company was already a ubiquitous presence in the field of commercial plumbing appliances when it asked us for help in creating an automatic, dual-flushing device that supplies a large or small volume of water based on sensor feedback.

To enable cost-effective installation without the need for extensive plumbing and electrical work, the new device needed to be an energy-efficient attachment for the company’s classic, 100-year-old fixture.

Sloan’s original flushometer was designed to flush a single amount of water regardless of toilet load. We needed to engineer a solution that would trigger the existing technology to dispense two distinct volumes of water.

Our team began by gaining a thorough understanding of how the existing flushometer functioned; after installing a site in the wall of the valve housing, we observed the mechanics of a flush through a high-speed camera and studied the footage. We discovered the existing handle activated a plunger that pushed on a small valve, and that shifting the position at which the plunger contacts the valve even a fraction of a millimeter would make the volume of water flushed vary greatly.

Once we determined how to trigger two different volumes of water, we devised a system, including an infrared sensor and timer, that would calculate whether to flush a large or small volume of water based on the user’s proximity to the sensor and duration of the visit.

In order to avoid frequent battery changes and compete with existing single-flush automatic mechanisms, the new dual-flush needed to be extremely energy efficient to achieve a long battery life.

By implementing a motor and a unique roller-based mechanism that took advantage of the city water pressure and valve dynamics during a flush, we ensured that our mechanism ran at the most efficient operating point.

The infrared sensor was set with a limited range and rate of scanning to optimize the device’s reliability and energy efficiency. In addition, we had to consider a wide variety of bathroom lighting approaches, as some common types can aggravate the infrared sensors used in the device.

  1. 01Initial prototype and model
  2. 02Two manual override buttons enable backup flush
  3. 03Units tested to ensure long lifetime

We created a product with two capabilities that no other product had at the time: automatic, variable volume flush and longest lasting battery life. The Dual Flush was successfully introduced to the market, and Sloan continues to dominate the plumbing appliance industry with this efficient and innovative technology.