Mixing Valves
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.
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 4 shows the approximate time-
In addition to using the lowest possible temperature setting that satisfies the demand of the application a Mixing Valve should be installed at the water heater (see Figure 8) or at the hot water taps to further reduce system water temperature.
Mixing valves are available at plumbing supply stores. Consult a Qualified Installer or Service Agency. Follow mixing valve manufacturer’s instructions for installation of the valves.
| Table 4 | |
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Water Temperature | Time to Produce 2nd & 3rd | |
Degree Burns on Adult Skin | ||
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160°F (71°C) | About 1/2 second | |
150°F (66°C) | About | |
140°F (60°C) | Less than 5 seconds | |
130°F (54°C) | About 30 seconds | |
120°F (49°C) | More than 5 minutes |
Dishwashing Machines
All dishwashing machines meeting the National Sanitation Foundation requirements are designed to operate with water flow pressures between 15 and 25 pounds per square inch (103 kPa and 173 kPa). Flow pressures above 25 pounds per square inch (173 kPa), or below 15 pounds per square inch (103 kPa), will result in improperly sanitized dishes. Where pressures are high, a water
pressure reducing or flow regulating control valve should be used in the line to the dishwashing machine and should be adjusted to deliver water pressure between these limits.
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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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| TO TANK | |||
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| INLET | |||
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Figure 8.
Space Heating and Potable Water System
Your water heater is equipped with inlet/outlet connections for use in space heating applications (see Figure 9). If this water heater is to be used to supply both space heating and potable (drinking) water, the instructions listed below must be followed:
•Be sure to follow the manual(s) shipped with the air handler or other type heating system.
•This water heater cannot be used in space heating applications only.
•This water heater is not to be used as a replacement for an existing boiler installation.
•Do not use with piping that has been treated with chromates, boiler seal or other chemicals and do not add any chemicals to the water heater piping
•If the space heating system requires water temperatures in excess of 120°F, a mixing valve must be installed per the manufacturer’s instructions in the potable hot water supply to limit the risk of scald injury.
•Pumps, valves, piping and fittings must be compatible with potable water.
•A properly installed flow control valve is required to prevent thermosiphoning. Thermosiphoning is the result of a continuous flow of water through the air handler circuit during the off cycle. Weeping (blow off) of the temperature and pressure relief valve (T & P) or higher than normal water temperatures are the fi rst signs of thermosiphoning.
•The hot water line from the water heater should be vertical past any mixing valve or supply line to the heating system to remove air bubbles from the system.
•Do not connect the water heater to any system or components previously used with
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