Insulating Pipes and Hot Water Tanks

Insulating your hot water tank and pipes is an easy way to save energy dollars. Most domestic hot water systems are stand-by systems--that is, water is kept hot and stored for immediate use. A hot water tank that is not properly insulated loses heat through the top and sides. Uninsulated hot water pipes, especially those in circulating systems, lose heat too.

Insulating the Tank

Most water heaters have some insulation built into the tank but it is almost always beneficial to add an insulation jacket to the water heater tank. The exceptions are new, high efficiency water heaters and instantaneous water heaters, which should not be insulated. Although the surface of the water heater may not feel warm, your tank may still be losing heat. To test, hold your hand against something metal in the same room, perhaps a metal shelf, a tool box, etc. Usually the other metal will feel cooler than the water heat tank, demonstrating heat loss from the tank.

Water heater tanks are usually insulated with fiberglass blanket insulation. Foil-faced fiberglass can be used or a kit that includes fiberglass insulation with a plastic cover and tape can be purchased. Install the jacket by wrapping it tightly around the sides of the tank and securing it with tape. Be sure not to cover air inlets on fuel-fired models and gauges and controls on all units. Because of ventilation considerations, extra insulation cannot be placed on top of a fuel-fired water heater; however, a top can be installed on an electric model. With the foil-faced fiberglass, use duct tape to secure the jacket.

Though most water heaters have factory-installed fiberglass insulation, some new tanks have foam insulation and will not need additional insulation. These water heaters may have a statement posted on the tank noting that installation of additional insulation will void the warranty.

Insulating Pipes

Hot water pipes, especially circulating systems, should also be insulated using foil-faced fiberglass insulation or foam insulation sleeves. With non-circulating systems, insulate the first five feet of pipe or all that is accessible. The fiberglass is installed in strips tied to the pipe with wire or tape every six to eight inches, foil facing out. The foam simply slips onto the pipe through a slit in the sleeve; the slit is then sealed with tape. Foam is more expensive than fiberglass, but preferred in areas where appearance is a consideration.

Your plumbing or mechanical contractor can install tank or pipe insulation or you can do it yourself. Both tank and pipe insulation kits usually provide installation instructions and are available at most hardware and home stores.