American Water Heater American Water Heaters Residential Gas Water Heater Water Heater User Manual


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9
TYPICAL INSTALLATION
FIGURE 2.
MIXING VALVE / THERMAL EXPANSION TANK USAGE AND SPACE HEATING
MIXING VALVES
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.
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inrmandthe
physically/mentally disabled. Table 1 shows the approximate time-
to-burn relationship for normal adult skin. If anyone using hot water
providedbythewaterheaterbeinginstalledtsintooneofthese
groups or if there is a local code or state law requiring a certain
water temperature at the point of use, then special precautions
must be taken.
In addition to
using lowest possible temperature setting that
satises
demand of application a Mixing Valve should be installed at water
heater(seeFigure3)orathotwatertapstofurtherreducesystem
water temperature.
Mixing valves are available at plumbing supply stores. Consult a
QualiedInstallerorServiceAgency.Followmixingvalvemanufacturer’s
instructions for installation of the valves.
TABLE 1.
WaterTemperature°F
Time for 1
st
Degree Burns
(LessSevereBurns)
Time for Permanent 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
(U.S.GovernmentMemorandum,C.P.S.C.,PeterL.Armstrong,Sept.15,1978)
HOT WATER
OUTLET
TO TANK
INLET
CHECK
VALVE
MIXING
VALVE
COLD
WATER
INLET
TEMPERED WATER
OUTLET
12” TO 15”
(30-38 cm)
CHECK
VALVE
FIGURE 3.
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