Greywater recycling: from concept to assessment

The Ekô heat exchanger offers a large exchange surface thanks to its spiral design. The ultra-thin design enables it to fit under shower trays. - Photo: WisElement

In October 2015, WisElement, a VSE, took advantage of the CSTB’s innovation advisory and support service, Ariane. Since then, it has been advancing step-by-step to increase the reliability of its innovative device for the instant recovery of heat from shower greywater. In 2016, the CSTB initiated a study of the technical and regulatory aspects of the innovation in the concept phase. The results may support a request for Technical Approval in 2017.

The innovation pathway

The purpose of the Ekô device developed by WisElement is to recover heat from shower water. What makes it special is the ultra-thin design that allows it to be installed under the shower tray, and its spiral circuit that provides a very large heat exchange surface. To finalize the design and consider a Technical Approval in the medium term, WisElement, a VSE, contacted the CSTB in October 2015 through its Ariane service.

The CSTB was given two tasks: analyze the fitness for use of the Ekô device, and measure its heat recovery performance. This comprehensive approach involves testing various aspects of the project relating to the installation of a walk-in shower, compliance of sanitary equipment, compatibility of materials in contact with water intended for human consumption, and measurement of energy performance.

Target requirements

In its 2016 analysis of the system, the CSTB identified the design choices that could invalidate its fitness for use in view of an assessment procedure. The company designing the system then had to propose changes.

WisElement chose to focus its innovation on the heat recovery system―without including the shower base initially planned. Also, based on the comments of CSTB experts, the company is now improving the separation between the heat exchanger channels: one for hot wastewater, the other for cold water that is heated. This separation must allow instant heat exchange while ensuring fluid-tight seals.

Second task, for 2017: measure energy performance. The CSTB will test the Ekô innovation in its Recado Laboratory for waste heat recovery systems to determine its efficiency in recycling greywater heat which is otherwise lost energy. WisElement’s objective: 40%. Testing will take place in the first half of 2017. Depending on the results, WisElement will apply for Technical Approval in fall 2017.

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