Minerals in Tank Make Water Heater Gurgle

QUESTION: I have a gas-fired, tank-type water heater. Lately, it has been making a rumbling noise after the water has been used and the heating starts again. This is the only time it makes that noise. Should it be replaced?

ANSWER: The water heater does not have to be replaced. Over the years sediment, scale and mineral deposits accumulate on the bottom of the water heater tank. Manufacturers suggest that a few quarts of water be periodically drained from the water heater to help remove these deposits. However, this practice is not always effective, and, if sufficient deposits accumulate, a rumbling or pounding sound can be heard when the unit is firing. It is not a dangerous condition, although the noise can be annoying. Also, the deposits act as an insulator between the water and the flame and decrease the heater’s efficiency.

Clogged Furnace Flue Can Be Dangerous

Q: I’ve heard that a clogged furnace flue can be the cause of an excessive humidity problem. Is this true?

A: Yes. A damaged furnace heat exchanger or a clogged furnace flue can push excessive water vapor into the house. Water vapor is a byproduct of combustion. A cracked heat exchanger in a forced-air furnace will release water vapor into the air being heated for distribution. A blocked furnace flue will cause water vapor and fumes to back into the house.

Either kind of a failure can be dangerous. Carbon monoxide is produced along with the water vapor and this would permeate the house as well. In a tightly sealed house, this odorless gas could prove deadly.

Play it safe. Should you have excessive moisture in your house, first make sure your chimney flue is clear and that the combustion gases from your heating system (including your water heater) are vented to the outside. Have a heating contractor or your local utility check your heating-ventilation system to make sure it’s operating properly.