A.O. Smith Residential Power Vent Gas Water Heaters with Hot Surface Ignition Start Up Conditions

For Your Information

Start Up Conditions

CONDENSATION

Whenever the water heater is filled with cold water, a cer- tain amount of condensation will form while the burner is on. A water heater may appear to be leaking when in fact the water is condensing. This usually happens when:

a.When a new water heater is filled with cold water for the first time.

b.When gas burns and water vapor is produced in water heaters, particularly high efficiency models where flue temperatures are lower.

c.When you use large amounts of hot water in a short time and the refill water is very cold.

Moisture from the products of combustion condenses on the cooler tank surfaces and form drops of water which may fall onto the burner or other hot surfaces and produce a “sizzling” or “frying” noise.

Because of the suddenness and amount of water, conden- sation 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 fami- ly’s demands for hot water including dishwashers, wash- ing machines and shower heads.

Excessive condensation may be noticed during the winter and early spring months when incoming water tempera- tures 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 com- bustion 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.

THERMAL EXPANSION

Water supply systems may, because of such events as high line pressure, frequent cut-offs, the effects of water ham- mer 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 sys- tem to be closed. As water is heated, it expands (thermal expansion) and closed systems do not allow for the expan- sion 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 heaters temperature-pres- sure 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 to relieve the pressure built by ther- mal expansion in the water system. Expansion tanks are available for ordering through local plumbing supply hous- es. Contact the local water supplier and/or plumbing inspector 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 represent harmful or dangerous conditions.

Condensation causes sizzling and popping with the burn- er area during heating and cooling periods and should be considered normal. See “Condensation” in this section.

Operational Conditions

SMELLY WATER

In each water heater there is installed at least one anode rod (see parts section) for corrosion protection of the tank. Certain water conditions will cause a reaction between this rod and the water. The most common complaint associat- ed with the anode rod is one of a “rotten egg smell”. 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 within the water heater. (This harmless bacteria is non-toxic 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 sup- plier for further information concerning an Anode Replacement Kit #9000029 and this Chlorination Treatment.

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