For Your Information; Start Up Conditions; Operational Conditions - A.O. Smith BTN-120 Instruction Manual

start up Conditions

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.
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 "Condensation" section in this manual.
Condensation
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 condensation.
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.

operational Conditions

hot water odor
In each water heater there is installed at least one anode rod 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 odor" in the hot water. The odor is a 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.

for your information

c.
d.
Hot water odor 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 water lines.
Contact the local water heater supplier or service agency for
further information concerning an Anode replacement Kit and
this chlorination treatment.
If hot water odor persists after anode replacement and chlorination
treatment, we 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
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 a manual reset type high
limit (energy Cutout) switch. The high limit switch interrupts
the main burner gas flow should water temperature reach
203°F (95°C).
In the event of high limit switch operation, the water heater
cannot be restarted unless the water temperature is reduced to
approximately 120°F (49°C). The high limit reset button on the
front of the thermostat then needs to be depressed. See Figure 2
for the location of the reset button.
33
A sulfate reducing bacteria which has accumulated
within the water heater (this harmless bacteria is
nontoxic to humans).
An excess of active hydrogen in the tank. This is caused
by the corrosion protective action of the anode.