Consulting-Specifying Engineer - January 2008 - (Page 19) M/E Roundtable capacity. A tankless system supplies an unlimited amount of hot water, but one is limited to the instantaneous flow versus temperature rise capabilities of the tankless system. A tank system supplies hot water to multiple fixtures for a brief period of time before running out of hot water. Then you must wait the recovery period before having hot water again. Storage heaters take up a great deal of space that can be used for other types of storage. CSE: What specifications maximize the advantages of storage heaters, such as controls or piping? LUTZ: Timers on the water heater help with energy consumption. Gas models with electronic ignitions also save on utilities. CSE: Under what circumstances are instantaneous —tankless —water heaters the right choice? LUTZ: Anywhere space, energy efficiency, and accurate temperature controls are required. Also, situations where long draws are required. Tankless heaters are wonderful in process applications where either intermittent usage or continuous hot water supplies are required. HOOVER: Tankless water heaters have little standby energy loss so applications where very little hot water is used and there are long periods of standby play to their advantage. Because they are not as efficient when their usage consists of many small draws as opposed to long, continuous draws, they will perform best in applications with long, continuous draws. ALFORD: Small projects with minimal needs for hot water, hand washing and occasional clean up chores. But on multistory residential projects, venting tankless water heaters can become an issue. Locating tankless water heaters on the exterior of the building could be less than desirable to the architect. There are some projects where the demand for hot water is a constant load, such as industrial processes or hospitals. Hospitals have a constant demand for steam, so using a semi-instantaneous steam water heater in a hospital a good choice. CSE: Under what circumstances are storage water heaters the right choice? LUTZ: If space is unlimited, or of little concern. If larger utility supplies for instantaneous units are not available or cost prohibitive. If especially large volume, short duration consumption habits are preferred. HOOVER: Storage water heaters are the most cost-effective alternative for most VFD-Induced Shaft Current Kills Motor Bearings! BEARING PROTECTION RING Guaranteed to Protect Bearings for Life! For motors up to 100 HP / 75 kw, AEGIS SGR’s patented technology is guaranteed to protect bearings against electrical fluting damage for the life of your motor. The AEGIS Bearing Protection Ring™ extends motor life and increases system reliability. To download a free technical paper on bearing protection technologies, visit our website: AHR EXPO: Booth 370 1-866-738-1857 | sales@est-aegis.com | www.est-aegis.com/cse1 Input #211 at csemag.com/quickResponse Consulting-Specifying Engineer • JANUARY 2008 19 http://www.est-aegis.com/cse1 http://www.est-aegis.com/cse1 http://www.est-aegis.com/cse1 http://csemag.com/quickResponse
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