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Tankless Efficiency

I'm just curious if anyone knows the procedures for testing AFUE on a tankless unit. Do they test it the same way they would test a boiler with perhaps a long burner on time, or do they factor in some short cycles caused by short draws (e.g. hand washing) of water that would be indicative of real world use?
Class 'A' Gas Fitter - Certified Hydronic Systems Designer - Journeyman Plumber


  • Larry Weingarten
    Larry Weingarten Member Posts: 3,142
    My understanding...

    ... is the standard DOE, EF test is used.  This is six equal draws, totaling 64.3 gallons.  The test unwittingly favors tankless design over tank-type.  There is an effort underway now to change the test to reflect more of a real world draw pattern. Here is a link to an interesting study of the EF test.  http://fire.nist.gov/bfrlpubs/build03/PDF/b03033.pdf

    Yours,  Larry
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