FOR EXAMPLE
: If the ON temperature is to be 115°F, then the OFF
temperature can be no higher than 105°F, but could be as low as 75°F.
36.
FOR EXAMPLE: If the SET temperatures 110°F and the operating “spread” between ON
and OFF is 5F°, then the water heater would cycle OFF at 115F°and cycle ON at 110F°
Temperature SPREAD between ON/OFF
PROGRAMMED
TEMPERATURE
SETTINGS
TO ON in (°F)
5°F SPREAD
BETWEEN
CLOSE (ON) ~ OPEN
(OFF)
TEMPERATURES
120
DEFAULTS TO ON
BOARD SETTING
115
115~120
110
110~115
105
105~110
100
100~105
95
95~100
90
90~95
85
85~90
80
80~85
75
75~80
The “on-board” thermostats on a hot water heater, coming from the factory, are usually
set at around 120°F. Homeowners can adjust the thermostats on the water heater but
the risk of setting the water temperature too high can increase the risk of scalding. Below
is a chart published by the U.S. Government, C.P.S.C. Department that highlights the
dangers of setting the thermostats higher than 120°F.
37.
User-programmed ON/OFF Temperatures
ON/
(°F)
OFF
120 115 110 105 100 95 90 85 80 75
120 X
X
X
X
X
X
X
X
X
X
115 X
X
X
X
X
X
X
X
X
X
110 OK
X
X
X
X
X
X
X
X
105 OK OK
X
X X
X
X
X
X
X
100 OK OK OK
X
X
X
X
X
X
X
95 OK OK OK OK
X
X
X
X
X
X
90 OK OK OK OK OK X
X
X
X
X
85 OK OK OK OK OK OK X
X
X
X
80 OK OK OK OK OK OK OK X
X
X
75 OK OK OK OK OK OK OK OK X
X
UNDERSTANDING SOFTWARE MATRIX/PROTOCAL WHEN USER ENTERS
TEMPERATURE PROGRAMMING FOR ON/OFF CYCLES. (Continued)
Water Time for Time for
Temperature °F 1
st
Degree Burns 2nd & 3
rd
Degree
(Less Severe Burns) (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 second
WATER TEMPERATURE ADJUSTMENT RECOMMENDATIONS
UNDERSTANDING SOFTWARE MATRIX /PROTOCAL WHEN
USER ENTERS TEMPERATURE PROGRAMMING FOR ON/OFF
CYCLES.
TEMPERATURE CONVERSION FORMULAS
To convert a F° temperature to C° do the following:
Take F° temperature, subtract 32 then divide by 1.8, equals C°
EXAMPLE:
120°F - 32 divide by 1.8 = 49 °C
To convert a C° temperature to F° do the following:
Take °C temperature, multiply by 1.8, add 32, equals F°
EXAMPLE:
49°C x 1.8 + 32 = 120°F
