Caleffi solar NAS200 Series, Installation, Commissioning And Servicing Instructions

Page: 7 / 24

Page 7
APPROXIMATE
TEMPERATURE/TIME
RELATIONSHIPS TO
SCALDING
120°F More than 5 minutes
125°F 1 1 ⁄
2
to 2 minutes
130°F About 30 seconds
135 °F About 10 seconds
140°F Less than 5 seconds
145°F Less than 3 seconds
150°F About 1 1 ⁄
2
seconds
155°F About 1 second
SECTION II: GENERAL INFORMATION (cont.)
TEMPERATURE CONTROL
The solar water heater is equipped with a backup electrical heating element and adjustable
thermostat. The thermostat is located behind the access cover on the side of the water heater.
If the solar system cannot satisfy the user demand, the electric element will energize and heat
the water until the thermostat is satisfied. An ECO (electrical cut-off) is included as part of
the temperature control and is designed to cut off power to the heating element in the event
the water in the tank reaches 180°F. The ECO is a safety feature on the water heater and
cannot be adjusted.
The thermostat is factory set at 120°F. See Table 6 for thermostat letter and temperature
relationships. If hotter water is required a thermostatic mixing device or scald protection
device must be installed at the domestic hot water outlet of the heater or at the point of use.
Table 3 details the approximate relationship of water temperature and time with regard to
scald injury. It is important for the user to understand the necessity of thermostatic mixing
or scald protection devices when using hotter water in domestic water heating systems.
CAUTION: Hot water in excess of 120 ° F can cause scalding!
Caleffi recommends a thermostatic mixing valve or scald protection valve be installed and
used according to the manufacturer’s directions to prevent scalding. Many state and local
codes now require installation of these devices. The thermostatic mixing valve or scald
protection valve will ensure potable water temperatures at the desired set point with a higher
degree of accuracy.
䊱
!
Table 3:
Scald Temperature/Time Relationships