Hot Water

Whether you’re heating water in the sun (see Chapter 10), using solar sys­tems to supplement your domestic water heater (Chapter 12), or just trying to cut down on how much energy your water heater uses, you can easily reduce your hot-water needs — without kicking anyone out of the house.

Practicing some stick hot-water conservation habits

Hot water consumes an average of 18 percent of a typical household’s energy needs. You can make a big difference in your power bill if you can just manage to change a few habits. Most of these suggestions are easy to imple­ment, and you’ll quickly find that your quality of life has been impacted only marginally.

✓ Use cold tap water. Most of the sink taps nowadays have a single lever for controlling both hot and cold water. You push the lever to one side to get hot and vice versa. Rarely do people actually want hot water, but inevitably they push the lever to the middle when they draw water for any use at all. Even though you’re not getting any hot water from the tap because it takes a while to get there, you’re still drawing hot water from the tank and wasting it. From now on, when you draw tap water, push the lever completely to the cold side.

image46On that subject, drawing hot water from the kitchen tap for use in cook­ing is wasteful. When you draw hot water, you need to wait a few min­utes for it to get there. You’re filling up all the intervening pipes with hot water in the process. Then you fill a cup, or a bowl with the hot water. The fact is, the amount of water in your pipes can be over ten or twenty times the amount you actually use. The heat dissipates and is wasted.

Heat cold water in the microwave oven. The stove is better than the tap, but not as efficient as a microwave.

✓ Run a full dishwasher. Washing a 12-piece dinner set of dishes by hand takes around 2.5 kWh of heated water. Washing the same dishes in a machine takes only around 1.5 kWh, and the dishes are much cleaner. You don’t need to rinse the dishes with hot water prior to putting them into the dishwasher. Most people prewash their dishes more than they need to.

✓ Take showers instead of baths. A five-minute shower takes a third of the water of a bath. If you want to spend half an hour soaking, a bath is better, but most people simply want to clean off.

✓ Lower the water temperature at the source. Set the temperature of your domestic water heater to 120°F instead of the scalding 160°F it’s probably at right now. Here’s a table of the costs of heating 64 gallons of water per day with electric power when you set the thermostat to differ­ent temperatures:

Temperature Yearly Cost (at 12 cents per kWh)

160°F $675

150°F $604

140°F $537

130°F $460

120°F $405

That’s a typical savings of $270 per year. Will you even be able to tell? Probably not. So why is it set so high? It’s the old school of thought, from back in the days when energy costs were inconsequential (not to mention concern about the environment). These were the same days when people smoked a lot of cigarettes because they were good for your health. I wonder if our children are going to look back and think that we were as ignorant as we perceive our forebears to be.

Fixing up your shower, pipes, and Water heater

You can also save energy just by making a few household repairs or improvements:

✓ Repair leaky faucets, especially hot water. The leak may seem tiny, but the cost adds up fast.

✓ Put a flow constrictor into your shower head. And take a look at how much water your current shower head is wasting. Is water going all over the place? What’s the point in aiming water at the walls? You also don’t need to turn the hot water up so that the windows steam. You can take a longer, cooler shower and save energy. (Of all the advice I give out about energy conservation, this is ignored more than any other. Many people simply can’t live without their long, hot showers. For these, a solar water heater is in order.)

image47Get a gallon container and turn your shower on. Measure how long it takes to the fill the container. Your flow rate is 60 divided by the mea­sured number of seconds. If it takes 15 seconds, your flow rate is 4 gal­lons per minute. A typical rate is 2.5 gallons per minute. A good energy conservation rate is around 1.75 gallons per minute. You also may want to measure the capacity of your pipes. Use the same container to mea­sure how much water flows through your shower head before it starts to get hot. When you’re finished with your shower, that much hot water is now sitting in the pipes, and the heat is wasted into the environment.

✓ Drain your domestic water heater twice a year through the valve at the bottom to remove water heater crud. Drain about two quarts into a bowl or container. You’ll get rid of the sediment that settles on the bottom that makes for less efficient heating. In most cases, the crud is very obvious; it’s a muddy, grey texture. And yes, this stuff gets into your water system, which means that it gets into your hair and your food.

Using on-demand Water heaters and heat recovery systems

An on-demand water heater doesn’t have a large reservoir of hot water. Instead, it uses a small heating chamber with super high-speed capacity. As water is drawn through the chamber, it heats it up to the set temperature within seconds, so you suffer no heat loss as the water sits there in a storage tank. This heater makes more sense in houses where you don’t use hot water for extended periods of time, such as in a vacation home that’s empty for entire seasons.

Look in the phone book for suppliers in your area. These systems are more expensive than conventional, but if you use hot water only occasionally, they’ll likely pay off.

A cheap alternative is to simply use a hot water tank blanket, which is a layer of insulation that you can buy for around $20 at most hardware stores. Write down the model of your hot water tank, and a clerk at the store can identify the size of the blanket that works best.

Updated: August 2, 2015 — 12:14 pm