John Wood Electric Water Heaters - NEW - Manual (Page 14)

14
THERMAL EXPANSION
As water is heated, it expands (thermal expansion). In a closed
system, the volume of water will grow. As the volume of water
grows, there will be a corresponding increase in water pressure due
to thermal expansion. Thermal expansion can cause premature
tank failure (leakage). This type of failure is not covered under the
limited warranty. Thermal expansion can also cause intermittent
temperature-pressure relief valve operation: water discharged from
the valve due to excessive pressure build up. The temperature-
pressure relief valve is not intended for the constant relief of
thermal expansion. This condition is not covered under the limited
warranty.
A properly-sized thermal expansion tank should be installed on all
closed systems to control the harmful effects of thermal expansion.
Contact a plumbing service agency or your retail supplier regarding
the installation of a thermal expansion tank.
STRANGE SOUNDS
Possible noises due to expansion and contraction of some metal
parts during periods of heat-up and cool-down do not necessarily
represent harmful or dangerous conditions.
OPERATIONAL CONDITIONS
WATER ODOR
In each water heater there is installed at least one anode rod (see
parts sections) for corrosion protection of the tank. Certain water
conditions will cause a reaction between this rod and the water.
The most common complaint associated with the anode rod is one
of a “rotten egg smell” in the hot water. This odor is derived from
hydrogen sulfi de gas dissolved in the water. The smell is the result
of four factors which must all be present for the odor to develop:
A. A concentration of sulfate in the supply water.
B. Little or no dissolved oxygen in the water.
C. A sulfate reducing bacteria which has accumulated within the
water heater (this harmless bacteria is nontoxic to humans).
D. An excess of active hydrogen in the tank. This is caused by the
corrosion protective action of the anode.
Smelly water may be eliminated or reduced in some water heater
models by replacing the anode(s) with one of less active material,
and then chlorinating the water heater tank and all hot water lines.
Contact the local water heater supplier or service agency for further
information concerning an Anode Replacement Kit and this chlorination
treatment. If the smelly water persists after the anode replacement and
chlorination treatment, we can only suggest that chlorination or aeration
of the water supply be considered to eliminate the water problem.
Do not remove the anode leaving the tank unprotected. By doing
so, all warranty on the water heater tank is voided.
“AIR” IN HOT WATER FAUCETS
HYDROGEN GAS: Hydrogen gas can be produced in a hot water
system that has not been used for a long period of time (generally
two weeks or more). Hydrogen gas is extremely fl ammable and
explosive. To prevent the possibility of injury under these conditions,
we recommend the hot water faucet, located farthest away, be
opened for several minutes before any electrical appliances
which are connected to the hot water system are used (such as a
dishwasher or washing machine). If hydrogen gas is present, there
will probably be an unusual sound similar to air escaping through the
pipe as the hot water faucet is opened. There must be no smoking
or open fl ame near the faucet at the time it is open.
HIGH WATER TEMPERATURE SHUT OFF SYSTEM
A non-adjustable high temperature limit control operates
before steam temperatures are reached. The high limit is
in the same area as the upper thermostat and must be
reset manually when it operates. BECAUSE THE HIGH LIMIT
OPERATES ONLY WHEN ABNORMALLY HIGH WATER
TEMPERATURES ARE PRESENT, IT IS IMPORTANT THAT A
QUALIFIED SERVICE AGENT BE CONTACTED TO DETERMINE
THE REASON FOR OPERATION BEFORE RESETTING .
• Turn off the heater electrical supply. Do not attempt to reset
thermostat with power on.
• Remove the screw securing the outer door and remove door.
• Remove or fold up the insulation to expose the reset button.
• Reset the high limit by pushing in the red button marked “RESET”.
• Replace the insulation so that it completely covers the thermostat
and element.
• Replace the outer door.
• Turn “ON” electric power to the water heater.
FOR YOUR INFORMATION