Some people are more likely to be permanently injured
by hot water than others. These include the elderly,
children, the in
fi
rm and the physically/mentally disabled.
Table 1 (published by U.S. Government Memorandum,
1978) shows the approximate time-to-burn relationship
for normal adult skin. If anyone using hot water provided
by the water heater being installed
fi
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.
Water
Temperature
°F
Time for 1st
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)
Table 1.
In addition to using lowest possible temperature setting
that satis
fi
es demand of application, a mixing valve should
be installed at water heater (see Figure 8 & Figure 9) or at
hot-water taps to further reduce system water temperature.
Mixing valves are available at plumbing supply stores.
Consult a Quali
fi
ed Installer or Service Agency. Follow
mixing valve manufacturer’s instructions for installation
of the valves. Before changing the factory setting on the
thermostat, read the “Operating The Temperature Control
System” section in this manual.
WATER HEATER OPERATION
Figure 10 shows the water heater’s sequence of operation
when a call for heat is initiated. The ignition control module
will attempt to light the burner three times. If the ignition
control does not detect ignition it will enter lockout mode
and
fl
ash the corresponding error code.
HEATER CONTROL
CHECKS TO ENSURE
BLOWER PRESSURE
SWITCH IS OPEN
BLOWER IS
ENERGIZED
CONTROL CHECKS
TO ENSURE PRES-
SURE SWITCH CLOSES
INDICATING BLOWER
IS OPERATING AND
THERE ARE NO
VENTING BLOCKAGES
(INLET OR OUTLET)
IGNITER IS ENERGIZED
AND MAIN GAS VALVE
IS OPENED
MAIN BURNER COMES
ON AND THE FLAME IS
SENSED BY CONTROL
MAIN BURNER CONTIN-
UES TILL THE WATER
IN THE TANK REACHES
THERMOSTAT SETTING
MAIN BURNER SHUTS
OFF. BLOWER
CONTINUES FOR A
POST PURGE TIME
HEATER
THERMOSTAT
CALLS FOR
HEAT
HEATER
REMAINS ON
STANDBY UNTIL
NEXT CALL FOR
HEAT
Figure 10.
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