It costs money to heat the water in your house. If the water cools
down while it's in the pipes used your hot water heater will have to
re-heat the water again. Insulating the hot water pipes leading from
your water heater will help maintain the temperature of the heated water,
reducing the amount of time you will need to wait for hot water when
you turn on a faucet or shower.
If you have a tank-type water heater, adding insulation can also reduce
heat loss. For moderately-well insulated tanks, for which you wish to
supplement the existing insulation, an less expensive tank wrap will
provide value. For under-insulated tanks that are obviously losing heat
through the side walls of the tank, use a wrap with a high R-value.
("R-value" is a measure of thermal resistance. The higher
the R-value, the more effective the insulating material is going to