GFX-STAR™ -- Next Generation GFX

DIY Project    Application Notes

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GFX-STAR™ is a new type of drain heat recovery (DHR) system that increases the amount of heat recovered in a conventional GFX system by raising the effectiveness of its Gravity Film heat eXchanger (GFX) as illustrated in Fig. 1. Other benefits include:

·        Easy Do-it-Yourself (DIY) retrofit of an existing DHR system or Solar Water Heater.

·        Cost effective recycling of wastewater heat from dishwashers, clothes washers, baths and hot tubs, without having to add convective chambers, wastewater storage tanks, or separate solids as required in other patented DHR-systems. 

·        Increase operating efficiency of a whole-house Model S4-60 GFX from about 30% up to 54% in typical households using 57% of their hot water for showers and sinks. (Figs. 1 & 2)

·        Offer similar savings in multifamily residential buildings using 34% of their energy budget for water heating. (Fig. 3)

·        Increase savings in hotels, college dorms and other buildings equipped with GFX systems that do not feed preheated water to a central boiler.

Fig. 1 Peak effectiveness of GFX-STAR compared to the conventional GFX system covered by U.S. Patent #4,619,311. Actual savings will depend on use pattern, water heater set point and plumbing configuration. (Above estimates assume 80% of a water heater’s output energy reaches the GFX’s drain input.) 

Fig. 2 Typical residential hot water usage; from Heat Recovery from Wastewater Using Gravity-Film Heat Exchanger, U.S. Department of Energy (DOE) by the Oak Ridge National Laboratory, DOE/EE-0247, May 2001.                             (

Fig. 3 Typical energy usage in multifamily residential buildings; from Five Tips for Reducing Energy Usage and Increasing Resident Satisfaction, Ken Gill, Multi-Housing News, April 2005.


© 2005 WaterFilm Energy Inc.

*Patent Pending: “Method of Increasing Heat Recovered by GFX™ System of U.S. Patent No. 4,619,311