Appliance Design - May 2008 - (Page 39)

INDoor AIr QuAlIty must be installed on doors and access panels to protect operators on locations where they could accidentally access a system and be exposed to UVC. UVC can significantly degrade organic components over time. Almost all organic materials can be degraded by UVC. Some materials, like synthetic media filters and insulation, are damaged quickly. Other materials, such as black motor drive belts and certain plastics, are quite resistant to UVC effects. UVC levels at various points in a system should be evaluated to determine if certain components need to be shielded from the UVC or if those components can be fabricated from a more UV-resistant material. significant UV irradiation. These issues are much more easily addressed during design and manufacture of the original equipment than they can be on a single unique system in the field. These reasons, coupled with the growing demand for UV, are why many makers of coils, air handlers, and full HVAC/R systems are considering or beginning to offer UV as a factory-installed option. The OEM can readily take the necessary measures to avoid the safety or material problems and provide for a robust simple installation. Several manufacturing approaches have been used to simplify installation of UV equipment at the OEM level. Generally, the UV equipment utilized is of a modular design. It can be easily mounted on a track or horizontal support and interconnected electrically. Units come in a variety of sizes to allow for proper sizing to any coil size. As the range of sizes and the variety of the OEM equipment is very large, several manufacturing approaches have been utilized. One approach is for the UV equipment supplier to provide a kit tailored for the OEM’s particular piece of equipment. This kit includes all the necessary supports, UV fixtures, switches, and accessories. It can be shipped and tagged with the OEM’s shop order to allow for easy installation during assembly of the system. Manufacturing solutions These hurdles can make it more practical to incorporate UV into the product at the OEM level, where they can be more easily overcome. During the design and manufacture of the equipment, HVAC/R components can be re-arranged to allow the space for the UV equipment. Electrical junction boxes can be included in the equipment wiring. Safety interlock switches can be installed at all user accessible panels and doors and integrated into the control system. UV levels in the system can be more accurately determined, and the appropriate UV-resistant material can be specified for all components that will receive uV system installed downstream of the air conditioning coil in a residential HVAC system (vertical system). Residential UV systems are designed for simple, safe and convenient installation. avoid damage to equipment and to prevent safety problems. The UV equipment must be installed in the proper location, generally downstream of the air conditioning coil. The UV lamp fixtures need a suitable supporting structure and space for installation and future maintenance. UV lamp fixtures are generally installed the full width of the coil with spacing that allows the fixtures to evenly irradiate the entire coil, including the irradiation of the drain pan. Electrical service must be supplied to the UV fixtures. The amount of UV intensity applied is extremely important, as too little may not keep the coils clean. Too much wastes energy, increases safety concerns, and may damage some organic components in the system. Fortunately, the intensity levels of UV for surface applications are very low, as the fixtures are generally left operating continuously so that the required dosage is achieved even at low intensity. There are also safety and equipment concerns which must be considered and are relatively simple to handle. The UV used in these applications is of the UVC wavelength (254 nanometer), which is harmful to skin and eyes. Therefore, safety interlock switches Example of uV system installed in a residential HVAC system. UV is applied directly downstream of the air conditioning coil to maximize energy savings benefits. applianceDESIGN May 2008 39 www.applianceDESIGN.com http://www.appliancedesign.com

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Appliance Design - May 2008 Contents Editorial Shipments/Forecasts News Watch New and Notable Displays & Indicators Elastomers Quality & Standards Indoor Air Quality IHHS Highlights New Products Classifieds Design Marts Advertiser’s Index Association Report: PSMA

Appliance Design - May 2008

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