Does Insulating a Water Heater Work?

Insulation Types and Materials

Wraps or blankets are the most common types of water heater insulation. Wraps come in different sizes to cover pipes leading to and from the water heating unit, and blankets are typically large enough to wrap around the water heater body, covering it from top to bottom, and are secured by ties or Velcro closures. The material used in the fillings of these insulators is typically the same fiberglass material used in the insulation installed in the walls and attics of buildings. The fiberglass is encased in vinyl or a reflective foil material, the latter being a better insulator based on its reflective properties.

The level of insulating efficiency is measured by R-values. These levels represent the effectiveness of the insulation materials and how well they protect the water heater from the coldness of the environment. Wraps and blankets with the highest R-values are the most effective insulators and are typically thicker and contain higher concentrations of insulation filaments and fibers.

Before you invest in a hot water heater insulator, accurately assess your needs. If your hot water heater is relatively new, it is probably installed with adequate factory insulation and no additional insulation is needed. Older hot water heater manuals usually include the R-value level of the tank to help you choose the best blanket. If you can’t access the R-rating information, feel the exterior of the tank. Hot or warm tanks are losing a lot of energy, so a wrap with a high R-rating of 16 is appropriate. Tanks that feel cool typically have at least some internal insulation, so you can use insulation with an R-rating between 10 and 16.

For more energy savings, wrap all the pipes connected to the water heater in insulating materials. This can increase the water temperature by 2 to 4 degrees Fahrenheit and decrease the instances of having to wait for water to heat in between showers and baths. You can also increase energy savings by lowering the thermostat on your water heater. Water heaters are commonly set at 140 degrees at factories but typical households can get by on water heated only to 120 degrees, which can lower water heating costs by 5 to 10 percent annually.