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Future Directions: Integrated Water Heater / Dehumidifier

In 2004, Oak Ridge National Laboratory began investigating the market potential for a dual-service integrated water heater and dehumidifier, sometimes called a water heating dehumidifier or dehumidifying water heater. Primarily designed for the residential market, some sectors of the commercial market such as health care facilities, hotels and assisted living facilities are also a potential target for the technology.

The integrated water heater/dehumidifier is a heat pump water heater with the necessary components and controls to allow dedicated dehumidification. It produces domestic hot water using only half the electricity of a conventional electric water heater, producing as a by-product cool, dry air, regardless of whether additional hot water is needed.

The potential for such an appliance lies in leveraging the high efficiency of heat pump technology and addressing growing concerns about humidity control in well-insulated new construction. Although primarily a water heating and dehumidification appliance, marketing of the equipment will also focus on the unit's ability to provide cool air.

Initial research revealed several impediments to the marketability of the water heater/dehumidifier, including:

  • To benefit from the dehumidification/cool air attributes, the appliance must be located within the area or structure to be dehumidified and cooled, making it of less value in areas of the U.S. where water heaters are situated in unconditioned crawl spaces or garages. Ideally, the unit should be located in a utility closet or enclosed basement, a problem in areas without basements or where closets are generally constructed too small to accommodate the appliance's anticipated 26-inch width
  • The likely higher cost and dehumidification benefits will be difficult to overcome or explain at the point-of-sale to builders who do not benefit from the energy savings and end users who are pressed into an emergency decision and do not understand the appliance's long-term cost savings and dehumidification benefits
  • Currently an installation and service infrastructure among contractors and installers does not exist for a piece of equipment that may require specialized training. It may also necessitate changing building codes to fit the needs of this new appliance
  • Lower operating costs and the ready availability of natural gas in much new construction make natural gas a strong competitor to the water heater/dehumidifier

Areas where the water heater/dehumidifier could make inroads include:

  • Buildings where the cool air benefits could reduce the air conditioning load
  • Areas where basements are very common
  • Areas where mold/mildew are a significant problem
  • Institutional laundries, to overcome the high heat and humidity of washers and driers
  • New construction being built to Energy Star specifications

The concept is under study and development through Oak Ridge National Laboratory and the Education and Research Consortium of the Western Carolinas, Inc. (www.ercwc.org), which is currently testing prototypes.