During times of energy crises and rising fuel costs, property owners tend to be more energy conscious. Water heater blankets are often considered for heat loss and conservation purposes.
Blankets for older fiberglass insulated electric water heaters make sense, especially since electricity is a much more expensive method to heat water than gas. Most electric water heaters insulated with foam (R 8.33 or higher) meet ASHRAE standards for performance (efficiency and standby loss) when tested according to Department of Energy procedures.
Many experts argue that heat loss in a gas water heater goes up the flue and therefore a blanket accomplishes no purpose.
Some local codes and utility company regulations may prohibit insulation blankets.
Too often, the Do-It-Yourselfer has good intentions but unknowingly creates hazards by:
Covering safety warnings and operating instructions. (These labels are not to be removed from the heater and placed on the blanket or elsewhere.)
Covering controls, access areas, shut off devices, temperature and pressure relief valves, etc.
Blocking air passages required for combustion or draft resulting in unsafe operation.
Consequently, the water heater manufacturer does disclaim any liability for problems associated with the use of insulated blankets.