For 24 hours every day, your water heater stands at the ready -- with 40 to 60 gallons of expensively heated water. It's there whether or not you're at home and whether or not you need it. Heat is constantly radiating from your tank. This causes your unit to continuously fire up to keep water fully hot. If the outer surface feels warm to the touch, heat is being lost. This means you pay. You well might know of water-heater insulation, but that doesn't necessarily mean you use it. If you don't, do! You can pick up an insulation kit at any hardware store or home center for about $10. It can be installed in minutes (all you need is a pair of scissors), and it can pay for itself in just one season. You get about 2 inches of fiberglass insulation covered outside with white plastic film. Just wrap -- trim to size -- and tape. While you're at it, add a retaining strap, too. In some states it's the law. And that's the On The House tip for today.