Insulating water heaters is an effective way of ensuring that hot water stays hot by reducing heat loss from the tank. Insulating both the tank and pipes properly can lead to savings of 4% to 9% in water heating costs. A general rule of thumb to understand whether your water tank requires additional insulation is to touch it. If the tank feels warm, it needs additional insulation to prevent heat loss.
The easiest way to insulate a water tank is to use precut insulation jackets. Insulation jackets or blankets are inexpensive solutions and usually cost between $10 and $20. Added insulation helps in saving up to 500-kilowatt hours of electricity annually. Tanks, which have an inner insulation of foam and not fiber glass, usually do not need additional insulation.
Jackets should have an insulation R-value of 8 to prevent heat loss. The R-value is an industry standard rating used to describe the insulation properties of a building. Higher R-values indicate greater insulation capabilities. Jackets are usually made of fiber glass with a vinyl covering. The insulation blanket is wrapped around the tank with the ends taped together. Rigid boards of insulation are also available and these are more apt for square tanks. These rigid boards can be placed under an electric water heater tank. This will help prevent heat loss into the wall or floor below the tank.
The tank’s location also determines whether the tank needs additional insulation or not. Water tanks located inside closets or in a small space will require less insulation. This is because the surroundings will help the tank to retain its heat.�
Similarly, if you have water pipes in the loft situated under the loft’s insulation, then additional insulation is not required. It is essential to insulate the vertical piping that is found just above the tank. Two common options for insulating a water pipe are mineral wool mats and pre-formed molded insulation strips. Wool mats are wrapped around the pipe like a bandage with no gaps and tied with a tape or string. Molded insulation strips slip over a pipe, and the ends are taped to ensure that there are no gaps.
Before insulating your water heater, check your water heater manual. Some water heaters specify that they should not be insulated with an additional jacket. Insulating such a water heater might cause damage to the heater, as it would operate at temperatures higher than recommended. When using an insulated water heater, the thermostat should be set slightly lower than normal, as the additional jacket retains heat.