What causes condensation, water dripping in the burner or on the floor around the water heater?


Many times gas fired water heaters are returned as leakers when the heater was not leaking, but rather condensation had formed. Condensation can most easily be defined as a reduction to a denser form (as from water to vapor). A perfect example of condensation is a glass of ice water on a hot day.

Whenever a water heater is filled with cold water, a certain amount of condensation 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:

  1. When a new water heater is filled with cold water for the first time.
  2. When gas burns and water vapor is produced in water heaters, particularly high efficiency models where flue temperatures are lower.
  3. When using large amounts of hot water in a short time and the refill water 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.

Excessive condensation can cause pilot outages due to water running down the flue tube onto the main burner and putting out the pilot.

Because of the suddenness and amount of water, condensation may be diagnosed as a “tank leak”. After the water in the tank warms up (about 1 to 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 condensation 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.

So, before you pull that heater out, check it one more time and make sure it’s not condensation your experiencing.

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