TYPICAL INSTALLATION
MIXING VALVE / THERMAL EXPANSION TANK USAGE AND SPACE HEATING
FIGURE 2.
Mixing Valves
heater (see Figure 3) or at hot water taps to further reduce system
water temperature.
DANGER
Water temperature over 125°F (52°C) can cause severe burns instantly resulting in severe injury or death.
Children, the elderly and the physically or mentally disabled are at highest risk for scald injury.
Feel water before bathing or showering.
Temperature limiting devices such as mixing valves must be installed when required by codes and to ensure safe temperatures at fixtures.
Mixing valves are available at plumbing supply stores. Consult a Qualified Installer or ServiceAgency. Follow mixing valve manufacturer’s instructions for installation of the valves.
TABLE 1.
Water Temperature °F | Time for 1st Degree Burns | Time for Permanent Burns |
(Less Severe Burns) | 2nd & 3rd Degree | |
| (Most Severe Burns) | |
|
| |
110 | (normal shower temp.) |
|
116 | (pain threshold) |
|
116 | 35 minutes | 45 minutes |
122 | 1 minute | 5 minutes |
131 | 5 seconds | 25 seconds |
140 | 2 seconds | 5 seconds |
149 | 1 second | 2 seconds |
154 | instantaneous | 1 seconds |
Water heated to a temperature which will satisfy clothes washing, dish washing, and other sanitizing needs can scald and cause permanent injury upon contact. Short repeated heating cycles caused by small hot water uses can cause temperatures at the point of use to exceed the water heater’s temperature setting by up to 20°F (11°C).
Some people are more likely to be permanently injured by hot water than others. These include the elderly, children, the infirm and the physically/mentally disabled. Table 1 shows the approximate time-
In addition to using lowest possible temperature setting that satisfies demand of application a Mixing Valve should be installed at water
(U.S. Government Memorandum, C.P.S.C., Peter L. Armstrong, Sept. 15, 1978)
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| HOT WATER | |||
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| OUTLET |
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| 12” TO 15” | ||
TEMPERED WATER |
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| OUTLET |
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COLD |
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| CHECK | ||
WATER |
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| VALVE | ||
INLET |
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| MIXING | ||
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| CHECK | |||
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| VALVE | |||
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| VALVE | |||
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TO TANK
INLET
FIGURE 3.
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