Consulting-Specifying Engineer - January 2008 - (Page 20) M/E Roundtable water heating applications. While tankless water heaters are more efficient than conventional storage water heaters, the cost savings do not justify the installed costs. For commercial applications with substantial hot water usage, condensing storage water heaters are more cost effective because their thermal efficiencies exceed 90%, while most tankless water heaters have efficiencies in the 82% range. In high hot water usage applications, the standby loss advantage of tankless heaters is swamped by the thermal efficiency of condensing storage water heaters. ALFORD: Projects with high demands for hot water during short periods of time are best suited for storage type water heaters. Any type of project with large numbers of showers such as a jail, prison, or school will need hot water quickly for short periods. In some cases a project with large kitchen hot water demands will work best with a storage type water heater. CSE : Assuming that they are not created equal, what are differentiating factors to consider when looking at tankless water heaters? ALFORD: Specifiers should consider the energy source the heater uses to make hot water, the material used in the heat exchanger, the recovery rates and efficiencies of each of the heaters, the physical size of the water heaters, and if service is available in the local area. HOOVER: The overall efficiency of the tankless water heater is an important consideration. In addition, the costs of installation and maintenance need to be considered. Availability of trained technicians to service the water heater should also be a consideration. LUTZ: Pay particular mind to construction in regard to material and durability of heat exchangers. High-quality sheathed elements with low to moderate Wattdensity for longer element life. Accurate and adjustable temperature control with custom tuning to your application. Proper voltage and phase availability for the installation location. CSE: Similarly, what are differentiating factors among storage water heaters? ALFORD: Selecting a tank water heater is like buying a car, there are many choices. Each water heater manufacturer knows the pros for his water heater over the other brands. The number of tank linings to choose from is endless. The venting options and efficiencies of the various types is another consideration. The first costs are an important consideration in the commercial design field as building developers look for an economical design. One consideration is the manufacturer representative. Will this person stand Energy-Efficient Lighting Controls stop energy waste Lighting Integrator lighting control panels offer the convenience of schedule-based control combined with the customization flexibility to match applications of any size and complexity. Maximize energy savings using a multi-level control strategy approach and seamless integration with occupancy sensors, daylighting controllers and external building management systems. Grouping loads for common control Automatic time out of after hour overrides No proprietary configuration tools required Set up using standard BACnet objects and BACnet compliant workstation Get information on Lighting Integrator Automation Level or Complete Control and a comprehensive product selection guide. 800.879.8585 | www.wattstopper.com/psg Complete lighting control solutions for every building. Occupancy and Vacancy Controls | Daylighting Controls | Lighting Control Panels | Wireless RF Lighting Controls Photo credit: John Swain/Photographer, HOK, and Beverly Prior Architects See us at AHR Expo booth #213 Alameda County Juvenile Justice Center San Leandro, CA Applying for LEED Gold I specified Watt Stopper/Legrand's Lighting Integrator system for this project because of its proven reliability and ability to handle the integration of the lighting control system with the BAS. The Lighting Integrator BACnet solution worked right out of the box. Todd Mazza, Senior Project Manager, Rosendin Electric Input #212 at csemag.com/quickResponse http://www.wattstopper.com/psg http://www.wattstopper.com/psg http://csemag.com/quickResponse
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