One of the most abhorrent standards ever devised is ANSI Z21.10.1, for gas water
heaters with 75,000 Btu/hour or less, as it is in its present form. Reason is the
tremendous allowance in testing to meet the standard.
A part of this standard for example gives a tolerance of plus or minus 10 F allowable
on the thermostat setting, or a 20 degree spread. In addition another test with a 160 F
thermostat setting pronounces the product satisfactory if the outlet water temperature
does not exceed 190 F, or a 30 degree spread in excessively high temperature hot water.
And UL 174 is the normal standard for certifying electric hot water heaters. The heater
tested under UL 174 is pronounced satisfactory if in effect, the heater does not develop
an electrical short circuit, nobody is electrocuted, and if nothing catches on fire.
These are good standards in the sense that the objectives are noble and worthwhile, but
these standards are for performance only in testing, and not for usage. When will the
subject of temperature control of the delivered hot water be addressed so that the
temperature will not be inaccurate by 30 to 40 degrees?
Burns
