Insulation water heater tank can be is simple and inexpensive, and it will benefit you in about a year. Find some pre-cut jackets or blankets available costing around $10–$20. Choose one with an insulating value of at least R-8.
Insulating an Electric Water Heater Tank

Shop Our Sponsors for These Blenders and Accessories Below

You can buy these items from eBay

RINNAI R94LSi TANKLESS WATER HEATER VA2535FFUD NAT    US $1,399.99

RINNAI R94LSi PROPANE TANKLESS WATER HEATER 94 GPM    US $979.99

RINNAI R94LSi TANKLESS WATER HEATER VA2535FFUD LP    US $1,399.99

RINNAI R75LSi TANKLESS WATER HEATER VA2528FFUD NAT    US $1,099.99

RINNAI R75LSi TANKLESS WATER HEATER VA2528FFUD LP    US $1,099.99

RINNAI R50LSi TANKLESS WATER HEATER VA2019FFUD NAT    US $1,029.99

RINNAI R50LSi TANKLESS WATER HEATER VA2019FFUD LP    US $1,029.99

Rinnai Tankless Water Heater R94LSI    US $870.00

Red and White 9620R Water Valve Isolation Kit    US $89.00

View Page:   1  2  3  4

You can probably install an insulating pre-cut jacket or blanket on your electric water heater tank yourself. Leave the thermostat access panel(s) uncovered. Don't set the thermostat above 130ºF on electric water heater with an insulating jacket or blanket—the wiring may overheat. You also might consider placing a piece of rigid insulation—a bottom board— under the tank of your electric water heater.

This will help prevent heat loss into the floor, saving another 4%–9% of water heating energy. It's best done when installing a new water heater. Water heater gas and oil-fired water heater tanks is more difficult than those for electric water heater tanks. It's best to have a qualified plumbing and heating contractor add the insulation.