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THERMAL EXPANSION
Water supply systems may, because of such events as high line
pressure, frequent cut-offs, the effects of water hammer among
others, have installed devices such as pressure reducing valves, check
valves, back flow preventers, etc. to control these types of problems.
When these devices are not equipped with an internal by-pass, and no
other measures are taken, the devices cause the water system to be
closed. As water is heated, it expands (thermal expansion) and closed
systems do not allow for the expansion of heated water.
The water within the water heater tank expands as it is heated and
increases the pressure of the water system. If the relieving point of
the water heater’s temperature-pressure relief valve is reached, the
valve will relieve the excess pressure. The temperature-pressure
relief valve is not intended for the constant relief of thermal
expansion. This is an unacceptable condition and must be corrected.
It is recommended that any devices installed which could create a
closed system have a by-pass and/or the system have an expansion
tank or device to relieve the pressure built by thermal expansion in the
water system. Expansion tanks are available for ordering through a
local plumbing contractor. Contact the local water heater supplier or
service agency for assistance in controlling these situations.
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
SMELLY WATER
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
sulfide 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.
The anode rod in a new glass-lined water heater works rapidly to
protect the tank. After a period of time the anode action slows and the
odor may dissipate.
A smelly water condition (Rotten Egg Odor) in your Point of Use water
heater can , in most cases, be resolved or reduced with the addition of
sufficient amounts of chlorine to eliminate the bacterial growth inside
the tank. This can be accomplished through the installation of a chlorine
feeder to the system or the periodic flushing of the water heater with
bleach as needed. On systems where the odor is mild and does not
occur too rapidly, a monthly flushing may be sufficient. In more severe
cases, a system feeder would be more appropriate.
“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 flammable 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 flame 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
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 two screws securing the outer door and remove door.
• Fold back the insulation to expose the reset button opening.
• Reset the high limit by pushing in the red button marked “RESET”.
• Fold back 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