For Your Information; Start Up Conditions; Operational Conditions - A.O. Smith Power Direct ventedGasModels Instruction Manual

start up condItIons

condensate
Whenever the water heater is filled with cold water, some
condensate will form while the burner is on. A water heater may
appear to be leaking when in fact the water is condensate. This
usually happens when:
a. A new water heater is filled with cold water for the first time.
b. Burning gas produces water vapor in water heaters, particularly
high efficiency models where flue temperatures are lower.
c. Large amounts of hot water are used in a short time and the refill
water in the tank is very cold.
Moisture from the products of combustion condense on the cooler
tank surfaces and form drops of water which may fall onto the burner
or other hot surfaces to produce a "sizzling" or "frying" noise.
Because of the suddenness and amount of water, condensate water
may be diagnosed as a "tank leak". After the water in the tank warms
up (about 1-2 hours), the condition should disappear.
Do not assume the water heater is leaking until there has been
enough time for the water in the tank to warm up.
An undersized water heater will cause more condensation. The water
heater must be sized properly to meet the family's demands for hot
water including dishwashers, washing machines and shower heads.
Excessive condensate may be noticed during the winter and
early spring months when incoming water temperatures are at
their lowest.
Good venting is essential for a gas fired water heater to operate
properly as well as to carry away products of combustion and water
vapor.
sMoKe/odor
It is not uncommon to experience a small amount of smoke and odor
during the initial start-up. This is due to burning off of oil from metal
parts, and will disappear in a short while.
closed water sYsteMs
Water supply systems may, because of code requirements or such
conditions as high line pressure, among others, have installed
devices such as pressure reducing valves, check valves, and back
flow preventers. Devices such as these cause the water system to
be a closed system.
therMal eXpansIon
As water is heated, it expands (thermal expansion). In a closed
system the volume of water will grow when it is heated. As the

for Your InforMatIon

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. This condition is not covered under the limited warranty. The
temperature-pressure relief valve is not intended for the constant
relief of thermal expansion.
A properly sized thermal expansion tank should be installed
on all closed systems to control the harmful effects of thermal
expansion. Contact a local plumbing service agency to have a
thermal expansion tank installed.
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.
Condensation causes sizzling and popping within the burner area
during heating and cooling periods and should be considered normal.
See "Condensate" in this section.

operatIonal condItIons

"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
This water heater is equipped with an automatic gas shut-off
system. This system works when high water temperatures are
present. Turn "OFF" the entire gas supply to the water heater.
The high temperature shut-off is built into the gas control valve.
It is non-resettable. If the high temperature shut-off activates, the
gas control valve must be replaced. Contact your gas supplier
or service agency.
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