Conventional hot water heaters with a storage tank can be an energy hog. In a typical home a water heater can account for up to 25% of the home's utility bill. When wrapped with SEI-25, these heat losses can be reduced by 40% or more. SEI-25 works great with both gas water heaters and electric water heaters.
If you don't know your water heater tank's R-value, touch it. A tank that's warm to the touch needs additional insulation.