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 The misconception has been that we either reduce the temperature even further at the heat source, as in nursing homes where water temperatures are kept at 105°F to 110°F (Legionella bacteria thrive best at these moderate temperatures, often resulting in positive tests and repeated attempts to eliminate the bacteria), or install a listed American Society for Sanitary Engineering Standard 1016 scald guard faucet at the point of use. Listed devices must be able to hold their set water temperatures within just a few degrees, typically plus or minus 3°F.The full name of Standard 1016 is “Individual Thermostatic Pressure Balancing, and Combination Pressure Balancing and Thermostatic Control Valves for Individual Fixture Fittings.” Three types of ASSE 1016 scald guard devices are listed: “P”, or pressure balancing; “T”, or thermostatic reacting; and “P/T,” representing those capable of reacting to both pressure and temperature fluctuations. All are equipped with field-adjustable limit stops that require the installer’s attention.
While that solves their short-term problem, it also inadvertently results in altering that previously set high limit safety stop in the P-style faucet. Do they know that or do their children understand the repercussions associated with the hotter water? Who is responsible? More often than not, economics have dictated the P-style valves are installed instead of the slightly more expensive T or P/T-style valves. Another issue known as “stacking” can occur in any hot water storage vessel, wherein layers of hotter water can stack up like pancakes at the breakfast buffet. In fact, this is a fairly common occurrence brought on by intermittent draw or a dripping faucet that triggers the burner. The regulation governing hot water storage vessels of 75,000 Btuh or less (Z21.10.1) in residential models, allows for that stacked outlet temperature to be as high as 190°F! So, what do responsible designers, code officials and installers need to do to ensure safe point-of-source, distribution and point-of-use potable hot water in residential, commercial and institutional systems? Tune in next month to explore more challenges we face and the set of guidelines that could well resolve this complicated issue. Dave Yates owns F.W. Behler, a contracting company in York, Pa. He can be reached by phone at 717/843-4920 or by e-mail at .
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Although the “P” style valves perform well and maintain bather protection under most conditions, they are blind to temperature fluctuations. Why is that an issue you ask? For starters, what have homeowners been doing ever since they began getting new water heaters set at the factory for 120°F and they run out of hot water more quickly compared to their older model? They crank up the thermostat to increase the storage temperature, thereby extending showering times because that changes the ratio volume of hot-to-cold water mixing.
