John Wood Commercial Electric Water Heater - Manual (Page 9)

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Temperature Control
All electric water heaters feature fully automatic controls to
regulate the water temperature. The thermostat supplied
with the water heater may be either an immersion or a sur-
face mounted type. Both types of thermostats use contact
relays to energize the electric heating elements. The ther-
mostats are located in the bottom control panel. The ther-
mostats are factory set to 60°C (140°F) to reduce the risk of
scalding. Water temperature adjustments for the immersion
type thermostat can be made by turning the temperature
adjustment dial, located on the outside of the lower control
panel, to the desired temperature setting. Water tempera-
ture adjustments can be made to the surface mounted ther-
mostat by first turning off the electric power supply to the
water heater and removing the bottom control panel cover.
Using a screwdriver, turn the thermostat dial to the desired
temperature setting. The water heater is equipped with a
surface mounted high limit control located under insulating
material in the top control panel. If for any reason the water
temperature becomes excessive, the high limit will de-ener-
gize the heating element circuit. Once the high limit has
been activated it must be manually reset by pushing in the
red reset button located on the high limit. The cause of the
excessive temperature should be determined and correct-
ed.
Water Heater Sounds
During the normal operation of the water heater, sounds or
noises may be heard. These noises are common and may
result from the following:
1. Normal expansion and contraction of metal parts during
the periods of heat-up and cool-down.
2. Sediment build up in the tank bottom will create varying
amounts of noise and may cause premature tank failure.
Drain and flush the tank as directed under “Draining,
Flushing and Sediment Removal”.
WARNING
Water temperature over 52°C (125°F) can cause
severe burns instantly or death from scalds.
Children, disabled and elderly are at highest risk of
being scalded.
Feel water before bathing or showering.
Temperature limiting valves are recommended.
Hot water produced by this appliance can cause severe
burns due to scalding. The hazard is increased for young
children, the aged, or the disabled where water tempera-
tures exceed 52°C (125°F). Use tempering valves in the
hot water system to reduce the risk of scalding at point-of-
use such as lavatories, sinks and bathing facilities. Such
precautions must be followed when this heater is operat-
ed in combination with dishwashing or space heating
applications.
WARNING
CAUTION
Hydrogen gas can be produced in a hot water system
served by this heater that has not been used for a long
period of time (generally two (2) weeks or more).
Hydrogen gas is extremely flammable and can ignite
when exposed to a spark or flame. To reduce the risk of
injury under these conditions, it is recommended that the
hot water faucet be opened for several minutes at the
kitchen sink before using any electrical appliance con-
nected to the hot water system. Use caution in opening
faucets. When hydrogen is present, there will probably be
an unusual sound such as air escaping through the pipe
as the water begins to flow. There should be no smoking
or open flame near the faucet at the time it is open.