A new electric water heater uses about 10 times more electricity than an average new refrigerator! Fortunately, heat pump water heaters using less than half as much electricity as conventional electric resistance water heaters are now available from several manufacturers-use the Enervee Score or check the ENERGY STAR lists for detailed information. We do not recommend the use of electric resistance water heaters due to the high operating costs. The minimum efficiency of electric resistance storage water heaters is about 0.90 (depending on tank volume), and the best available are 0.95 EF. Look for the “thermal efficiency” rating rather than EF, with values of 0.90 and above. These have input capacity greater than 75,000 British thermal unit per hour (Btuh). No residential-rated condensing water heaters (energy factors 0.80 or higher) are yet available, but small commercial-rated models are marketed for residential use. The most efficient conventional gas-fired storage water heaters are ENERGY STAR models with energy factors between 0.67 and 0.70, corresponding to estimated gas use of 214 to 230 therms/year. If your utility company offers off-peak electric rates and you’d like to use them, you may need to buy a larger water heater to provide carry-over hot water for periods when electricity is not available under this “tariff.” Compared to small tanks, large tanks have a greater surface area, which increases heat loss from the tank and decreases the energy efficiency somewhat, as mentioned above. Table 6.1 Federal Requirements for Storage Water HeatersĪll other things being equal, the smaller the water heater tank, the higher the efficiency rating. New efficient water heaters can help reduce this excess heat loss. In a conventional gas storage water heater, less than 50% of the fuel energy reaches the point of use. Updated standards, effective in 2015, are summarized in Table 6.1. The first national appliance efficiency standards for water heaters took effect in 1990.
The energy efficiency of a storage water heater is indicated by its energy factor (EF), an overall measure of efficiency based on the assumed use of 64 gallons of hot water per day, regardless of tank size. As for distribution losses- a problem common to all types of water heaters, look in the section on “Upgrading Your Existing Water Heater” for tips.Įfficiency and tank size. New energy-efficient storage water heaters contain higher levels of insulation around the tank to reduce this standby heat loss. Because heat is lost through the walls of the storage tank (standby heat losses) and in the pipes after you’ve turned the faucet off (distribution losses), energy is consumed even when no hot water is being used.
The hot water is always there, ready for use. When you turn on the hot water tap, hot water is pulled out of the top of the water heater and cold water flows into the bottom to replace it. Ranging in size from 20 to 80 gallons (or larger) and fueled by electricity, natural gas, propane, or oil, storage water heaters work by heating water in an insulated tank. Storage water heaters are by far the most common type of water heater in use in the U.S. Often you can substantially reduce your hot water needs through water conservation efforts (see “Conserve Water”). Look for a water heater that satisfies your hot water needs and uses as little energy as possible. Whether you’re replacing a worn-out existing water heater or looking for the best model for a new house you’re building, choose carefully. The energy savings alone could pay for the new water heater after just a few years, and you’ll be happy knowing that you are dumping fewer pollutants into the air and less money down the drain. In fact, it often makes sense to replace an inefficient water heater even if it’s in good shape. If it’s in bad shape, replace it now before it starts leaking or the burner stops working. If yours is up there in age, have your plumber take a look at it and advise you on how much useful life it has left. Most water heaters have a lifespan of 10–15 years. If possible, replace your existing water heater before it fails.
This is particularly important with newer energy-efficient technologies. Figure out the proper size for your household, not just in terms of gallon capacity, but first-hour rating as well. A much better approach is to do some research now.Įxplore the options and decide what type of water heater you want - gas or electric, storage or demand, stand-alone or integrated with your heating system, etc. You’ll have to rush out and put in whatever is available, without taking the time to look for a water heater that best fits your needs and offers real energy efficiency. That will happen at the worst possible time - like just after guests arrive for a week-long visit. If you’re like most people, you’re unlikely to go out looking for a water heater until your existing one fails.
0 kommentar(er)
