How efficient are commercial water heaters when used in a single residence?
Commercial water heaters receive a Thermal Efficiency, rather than an AFUE rating. TE does not convert to AFUE as the testing protocols are different. Thermal Efficiency is a snapshot reading at steady state and AFUE is a seasonal rating that takes into account cycling and other losses. If a commercial water heater was tested using the AFUE protocol, the AFUE would be substantially lower than the TE figure. Here are the questions… First, is it assumed that a commercial unit in a commercial setting is under almost constant demand, and therefore the cycling losses are inconsequential? Second, if units like the Polaris are suitable to use in both settings, should they be required to be tested to establish both a TE and an AFUE? I’m a HERS Rater and I see a lot of these units being used but the application in a single family residence looks like a poor choice if the desired effect is to install a high efficiency boiler. Can someone fill me fill me in?
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