Heating water consumes the second largest amount of energy in your house. About 20 percent of the energy used by the typical American house goes to heat water, compared with about 70 percent for space heating, and about 10 percent for lighting, cooking, running appliances, and so forth.
Frustratingly, there are only a few measures you can take to reduce the waste; however, all of these are easy, inexpensive, and will pay back your in vestment within a few years—usually one or two.
The easiest and least expensive conservation measure involves simply lowering the thermostat setting on your hot-water tank. When the temperature of the water is reduced, the difference between the water tank temperature and that of the surrounding air is also reduced. This means that less heat from the tank will be lost to the cooler air surrounding it. There are other less significant savings. For instance, dishwashers and washing machines that are regulated by a lower thermostatic setting will continue to use the water-temperature mix for which they have been set, only now they will use less hot water. Occasionally, dishes may appear spotted after the cooler wash, but the Department of Energy still recommends keeping dish-washing temperatures as low as 120-degrees.
Some dishwashers come equipped with both built-in heat sensors and with heaters that raise the temperature of the water to 140° during the final rinse cycle at the rate of about 1 degree every 2 minutes, no matter what the temperature of the water is as it enters the dishwasher. If your dishwasher has such a sensor, it makes little sense to keep it running for the extra 40 minutes or more that an initial 120° water temperature will elicit, in which case you may want to keep your water heater temperature high. If you don’t know whether your machine is equipped with a heat sensor, ask your service person or call your dealer.
Water heater thermostats typically are set at about 140°, with some as high as 150° to 160°. But almost no household use requires water temperatures above 120° (except for those dish washers mentioned above), and 110° is satisfactory for most hot-water uses. Whether you set your heater’s thermo stat at a high figure to accommodate your dishwasher or set it lower and wash your dishes by hand is up to you. You should know, however, that the cost of heating 1 00 gallons of water in your heater to 160° from an inflow temperature of 50° is nearly 30 percent greater than heating those same 100 gallons to 120°. The dollar translation for you will depend on which fuel you use to heat your water, and what price you pay for it. But you can pay as much as $5 per month for every 10 degrees your water is heated above 120°.
• Insulating your water heater: The next step is to add insulation to your hot-water tank. If it feels warm when you touch its sides, especially if your tank is in an unheated basement or on an open back porch, this is a must-do project.
All commercially available hot-water tanks are made with some interior insulation—electric heaters have 2 inches of insulation; oil- and natural gas-fired heaters have about 1 inch. These heaters tend to lose about 20 to 35 percent of their heat through their walls. A single, 3½-inch-thick roll of R-11 fiberglass blanket, sealed with duct tape and costing about $40, will be sufficient to wrap a 50-gallon tank, and will pay for itself in one or two years. You can also buy precut kits, but the job is so simple and cheap that you can cut the insulation yourself with little work.
When insulating your water tank: (1) do not block the pilot light or access to controls on any gas heater; (2) do not cover the top of a gas heater or put the insulation anywhere near the burner; (3) if you don’t expect to use hot water for a protracted period of time, make sure your gas or oil heater has a pres sure-relief valve. Otherwise, the addition al insulation may make the water over heat. Many states have codes that re quire such valves—if you aren’t sure about your state, call your public utility company; and (4) make a note of your serial number in case you need to get a part for your particular model.
When insulating your hot-water heater, you might also insulate the first ten feet or so of hot- and cold-water lines coming from the tank. This will minimize how long you’ll have to wait for the water that comes out of your faucets to reach the desired temperature. Although such insulation may not save you much in terms of either money or heat loss, if your pipes pass through an unheated area where they might freeze in winter, this task may be worth your while. To save money, you can use a lesser insulation, such as a combination vinyl foam/aluminum foil self-adhesive tape, on the pipes, and a superior-quality insulation on the tank. There is also an insulating tape available for use on joists.
How to Insulate a Water Tank: Gas heater and Electric
heater.
1. Measure your hot-water tank.
2. Measure a piece of insulation by placing it around the tank. Then remove it and trim accordingly.
3. Rewrap the insulation around the tank.
4. Seal the joint with duct tape. Keep the insulation away from the pilot light, if there is one.
Pipe insulation:
• Maintenance: Your water heater is a piece of machinery in a system of its own. Like a furnace or an air conditioner, it should receive a periodic checkup from a trained service person who will de-lime the tank in hard-water areas, clean the burner, or clean the electrodes, depending on whether your heater runs on gas, oil, or electricity. and every three or four months you should drain a gallon or two of water from the bottom of the tank. This will remove the sediment that, if left in the tank, will keep the water insulated from the burner flame.
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