Water Heaters Tips

Because the water heater is the second largest energy user in most homes, right behind space heating and cooling, it's a good place to find energy savings. Depending on where you live it can account for 10 to 20% of your total energy bill, so it's worth taking some time to investigate possible improvements. The primary ways to cut your water heating bills are: reducing waste by using less hot water, turning down the thermostat on your water heater, insulating your water heater and pipes, or buying a new, more efficient water heater.

Reduce Waste by Using Less

A dripping faucet wastes water and if it's dripping hot water, it's wasting energy, too. Often requiring nothing more than a new washer, fixing leaks is one of the quickest and least expensive ways of reducing your energy and water bills.

Another way to reduce waste is to take showers or baths depending on which uses less water. Some think showers use less hot water than baths, others say baths use more. They are both right. Which is correct for you depends on how long and hot your showers are and how deep and warm your baths are.

If you want to know which would use less energy for you, compute the flow rate of your shower and your tub. Flow rate is easy to compute. Just find a watch with a second hand and locate a one-gallon container. A milk jug or ice cream carton will do. Now see how long it takes to fill the one-gallon container from the shower and from the bathtub faucet. Take the number of seconds it takes and divide that number into 60 since there are 60 seconds in a minute. If it fills in 15 seconds, its flow rate is 4 gallons per minute. At that flow rate, a 5-minute shower uses 20 gallons. Now, simply time your next shower and the next time your tub fills and voila, mystery solved.

Reduce Waste by Lowering Flow Rates

Using less hot water may be easier than you think. Water conserving showerheads and faucet aerators can cut hot water use in half. To see if this will work for you, first determine what your faucet and shower flow rates are now.

Standard showerheads typically deliver 4-5 gallons per minute. Low-flow showerheads that use no more than 2.5 gallons per minute can be substituted. But be sure to get good quality products that do not simply restrict the flow, resulting in unsatisfactory performance. Ones that provide just a mist are not usually acceptable. Low-flow showerheads cost as little as $10 and should pay back that initial investment quickly in reduced energy bills.

Bathroom faucets usually have flow rates of 2 to 4 gallons per minute. Aerators cost just a few dollars, are easily installed, and can lower that rate to one-half to 1 gallon per minute. Just don't install them on faucets where your primary objective is filling something because it will take two to four times as long to fill with the lower flow rates.

One nice feature that really extends the value of these energy saving devices is an on-off valve. It allows you to turn off and on the water without changing the mix between hot and cold water. In a shower, this feature allows you to lather up and scrub with the water shut off, then press the button and the water comes back on at the same temperature mix for rinsing off.

Insulate the Tank

If your water heater is warm to the touch, installing an insulating jacket is one of the most effective do-it-yourself energy-saving projects. The insulating jacket will reduce standby heat loss by about 30%, saving about 5% on your water heating bills. Available at most hardware and home improvement stores, water heater insulation jackets cost $20 to $30.

Some newer water heaters come with fairly high insulation levels, reducing advantages of adding additional insulation. In fact, some manufacturers recommend against installing jackets on their energy efficient models. Always follow directions carefully when installing an insulation jacket. Leave the thermostat accessible. Remember, electric resistance units often have two, one toward the top and one toward the bottom. With gas and oil-fired water heaters, be careful not to restrict the air inlets or allow insulation near the combustion area.

In addition to insulating the tank, you may want to go ahead and insulate the hot water pipe, especially if it is located in unconditioned space. The insulation will reduce the heat loss as hot water travels to its destination at the tap. Also, insulate the first few feet of both water pipes extending from the top of your water heater. Just like a metal spoon in a cup of hot coffee radiates heat, so do both the hot and the cold water pipes. Insulation will reduce this heat loss.

Lower Water Heater Thermostat

One of the quickest, easiest and surest energy saving measures is lowering the thermostat setting on your water heater. Although some manufacturers and installers set water heaters at 140°F, settings between 115° and 120°F work fine for many households. That's a bout midway between the "low" and "medium" settings on most water heaters. The bottom line is keeping your water heater set at the lowest temperature that provides you with sufficient hot water. You can always try turning it down, then inch it back up if you find you are running out of hot water or having other problems. Moreover, there is a safety benefit to lowering your water heater temperature. Water heated to 140°F water can pose a scalding hazard, especially a concern where young children have access to faucets.

To check if the temperature of the water coming out of your faucets is close to your thermostat setting, fill a glass with hot water, and then place a thermometer in the water until the temperature stops rising. If you decide to change the water heater setting and you have a gas unit, simply turn the knob to a lower setting. On gas water heaters, thermostats are usually visible knobs at the bottom of the unit with clearly marked settings of High, Medium, and Low. If your water heater is electric, turn off the power at the circuit breaker before removing the access panels and making the adjustments. Electric water heaters often have two thermostats -- one for the upper heating element and one for the lower heating element. These should be adjusted to the same level to keep one element from doing all the work and wearing out prematurely.

If you have a dishwasher without a booster heater, you may need to keep the water temperature up to 140°F, the "medium" setting, or buy a new, more efficient, dishwasher with a booster heater. Usually, 140°F water is necessary to dissolve most dishwasher soaps. Not only will lowering the thermostat save energy, but it will also increase the life of your water heater and reduce the risk of children scalding themselves with the hot water.

When you plan to be away from home for 3 or more days, turning the water heater thermostat down to the lowest setting, or even turning the heater off completely, can help you achieve additional savings.

To estimate your potential for savings, for each 10°F reduction in water temperature, water-heating energy consumption can be reduced 3% to 5%.

Heat Recovery Devices

Waste-heat recovery devices, sometimes called hot gas reclaim systems, take heat where it is unwanted, from your air conditioner's or heat pump's outdoor heat rejection coil, and moves it where it is needed, to your hot water tank. In so doing, these devices can reduce water heating costs substantially while also reducing air conditioning costs.

It may sound too good to be true, but it works well, particularly in hot climates. In areas that have high cooling loads and a long cooling season, enough heat may be reclaimed to meet the home's entire hot water requirements during the summer months.

With a waste heat recovery device, such as a desuperheater, the air conditioner operates more efficiently, because it does not have to work as hard exchanging its waste heat. Instead of rejecting its heat to the warm outside air, it gets to reject it into much cooler water. Then the heat deposited in the water heater is essentially "free." With the waste heat recovery device in place, a typical house air conditioner or heat pump produces about 25 gallons of water per hour heated to 130°F.

Since heat can be re-claimed only while the air conditioner is operating , the storage tank must have supplemental heating capabilities for when the air conditioner is not "on." Even when it does not meet the entire demand, re-claimed heat contributes some heat that would otherwise have to be supplied by the water heater.

Waste heat recovery devices can be installed during construction or retrofitted to existing water heater storage tanks. Most are enclosed in metal cases and mounted either on a wall outside near the air conditioner condenser or inside near the water heater.

To find out about availability and performance for these devices in your area, ask a Service Technician or Utility Representative about waste heat recovery devices.

Sizing Water Heaters

To select the right water heater for your home, you need to consider family size and whether your usage would be considered high or low demand. We'll assume you know the family size, so all you have to determine is your usage profile. Review the following criteria. You are considered high demand if...

1. You have more than two full bathrooms in the home.
2. There are now or will soon be teenagers living there. Teenagers can significantly increase the amount of hot water needed for washing clothes and showering.
3. You have a very large bathtub or oversized whirlpool bath. The guideline is, your water heater tank capacity should be equal to your bathtub capacity. For example, if your tub holds 75 gallons, you should get a 75-gallon water heater.

Find your Family Size in the chart, and read across to find the First Hour Rating Requirement for your family. If your family qualified as high demand, consider moving up to the next First-Hour Rating level.

FAMILY SIZE	FIRST-HOUR RATING REQUIREMENT
2 People	45 - 55 Gallons
3 People	55 - 65 Gallons
4 People	65 - 75 Gallons
5 People	75 - 85 Gallons
6 People	85 - 100 Gallons
7 or More People	100 or More Gallons

Source: A.O. Smith

Selecting the Right Water Heater

The first step in choosing a water heater is to determine the appropriate fuel type. Natural gas, oil, and propane water heaters require venting, which may limit where they can be located. Electric units require no venting, which gives more flexibility in locating them. If you are considering electricity, check to be sure you are on off-peak electricity rates if they are offered. If available, heating your water during off-peak hours will cost less.

In mild climates, you may want to consider a heat-pump water heater, which is two or three times more efficient than a direct resistance electric water heater. Though a heat-pump water heater may have a high initial cost, it can save up to 50% of your water-heating bill in moderate climates. Heat pumps can be added on to your water heater or purchased as an integral part of a new water heater.

The efficiency of water heaters is indicated by their energy factor (EF), which is based on recovery efficiency, standby losses, and cycling losses. The higher the EF, the more efficient the water heater. Electric resistance water heaters have EFs ranging from 0.7 and 0.95; gas water heaters from 0.5 and 0.65, with some high-efficiency models ranging around 0.8; oil water heaters from 0.7 and 0.85; and heat-pump water heaters from 1.5 to 2.0. Everything else being equal, select a water heater with the highest energy factor (EF). Also, look for a water heater with at least one-and-a-half inches of tank insulation.

In the United States, all water heaters are sold with EnergyGuide labels to indicate their energy efficiency. These labels provide estimated annual operating costs, and also indicate the cost of operating the models with the highest annual operating cost and the lowest annual operating cost. By comparing a model's annual operating cost with the operating cost of the most efficient model, you can compare their efficiencies.

Although some consumers buy water heaters based on the size of the storage tank, the first-hour rating (FHR), provided on the EnergyGuide label, is actually more important. The FHR is a measure of how much hot water the heater will deliver during a busy hour. Before you buy a water heater, estimate your household's peak-hour hot water use (your water use during morning showers, for instance) and look for a unit with an FHR in that range.

Plan the Purchase of a New Water Heater

Most people shop for a new water heater when their old one fails, which is understandable. Who wants to even think about spending money replacing something that still works? The problem with that approach is that when it fails, you are out of hot water and under time pressure to get a new one installed right away. If your water heater is more than ten years old, doing some research now, before your heater fails, will enable you to select one that best suits your needs. Life expectancy for electric water heaters is about 14 years, and gas units range from 11 to 13 years depending on the type of water heater lining and water quality.

Before selecting a new water heater, the size of the family, the size of the bathtubs, and the size of the budget are just three factors you'll need to take into consideration. You'll want one sized to provide enough hot water, and look for the more energy efficient models. They usually cost a little more, but the extra dollars up front come back to you every month in the form of lower operating costs. For big families or large homes with high hot water demand, look for units that have fast recovery rates. Also, check the unit's EnergyGuide label that enables you to compare that model with other similar models and get a feel for what its annual operating costs are likely to be.

Home | Index | FAQs