Installing foam gaskets behind outlet and switch plates on the walls is a great way to ensure that your gas heater plumbing system is properly sealed and insulated. It's also important to inspect any visible insulation for air leaks and mold. To keep your water heater's ventilation system in top condition, it's recommended to clean and repair your gas appliance at least once a year. Additionally, the chimney should be lined and in good condition.
It's essential to make sure that the ventilation system is the right size for the water heater. If the ventilation system was previously sized for another gas appliance that has been removed, it may now be too large. This is often caused by fans, such as bathroom or kitchen fans, which draw air out of the house and create a vacuum effect that draws exhaust gases down and into the house from the water heater's ventilation grille. It's possible to use a fan to obtain combustion air, but there are many designs that are vented through a side wall and a plastic vent whose exhaust grilles cannot be safely used for an atmospheric vented gas water heater. Moving the burner of a gas water heater outdoors is not recommended, as it could lead to obstruction in the air holes or flue gas. Electrically vented water heaters come with an electric fan (often very quiet) installed on top of the water heater and can have vertical or horizontal ventilation ducts.
The table above is adapted from the AO Smith Gas Water Heater Owner's Manual for FSPH-75 270 Series gas models. All water heater ventilation systems use a ventilation duct or pipe, also called a chimney or combustion duct, to carry exhaust gases from the water heater to the outside. The lower BTUH of a gas water heater (compared to a furnace or heating boiler) may not be able to heat the inside of the chimney enough to generate an air current. To ensure reliable quotes and excerpts on proper ventilation of gas water heaters, refer to the latest edition of the National Combustible Gas Code or, in Canada, the Natural Gas and Propane Installation Code for complete information on “Procedure that must be followed to put equipment into operation”.Ventilating a gas water heater inside a housing is dangerous, as it could lead to insufficient combustion air, deadly carbon monoxide, and other hazards. Do not vent this water heater in the ventilation system of another gas appliance designed to vent under positive pressure. To ensure your gas heater plumbing system is properly sealed and insulated, it's important to install foam gaskets behind outlet and switch plates on walls.
Inspect any visible insulation for air leaks and mold, clean and repair your gas appliance at least once a year, make sure your chimney is lined and in good condition, check that your ventilation system is the right size for your water heater, avoid using fans that draw air out of your house, use an electric fan if necessary, refer to the National Combustible Gas Code or Natural Gas and Propane Installation Code for reliable quotes on proper ventilation of gas water heaters, and never ventilate a gas water heater inside a housing.
