WATER HEATER

GOALS:

To become aware of designs and construction that will save energy, cost less to operate and will have less of a negative impact on the natural environment.

OBJECTIVES:

The student will demonstrate knowledge and understanding of domestic hot water use and how it is produced and controlled in the home.

GLOSSARY:

Aerators - A cap on the water faucet that introduces air to the water flow.

P-Trap - A reverse bend in the water line. (See Figure 1)

Flap Valve - A one way valve.

LESSON/INFORMATION:

Do you ever stop to wonder how great it is to have running hot water in the home? Your lifestyle would be very different if this were not so. Do you realize hot water is the second greatest energy demand on your home? Only air conditioning and heating consume more.

Domestic hot water requirements are based on 20 - 40 gallons for each person in the home. Homes with dishwashers require the upper limits. The first step is to conserve the amount of hot water you use. Take a shower rather than a bath and use a low-flow shower head. Aerators are useful on all home faucets. They reduce water flow by mixing air with outcoming water. Switch your clothes washer from hot wash / warm rinse to warm wash / cold rinse. Run your dishwasher only when it is fully loaded. All of your appliances should be energy efficient. Leaky hot water faucets also waste energy dollars. One drop a second will waste 400 gallons a year of expensive hot water.

Another way of wasting energy dollars is by the loss of heat from the tank and pipes. Put your hand on the water tank. If it feels warm, it should be better insulated. Standard insulated jackets are made for most water heaters. All hot water pipes should be insulated to prevent heat loss. Put a P-trap (See Figure 1) or flap valve on the incoming cold water line to prevent hot water from rising in that line. You should also drain your water heater once a year. This prevents sediment build-up at the bottom of the tank. Usually draining a gallon or two from the bottom is all that is required.

Figure 1.

You can also lower the thermostat to save energy and prevent scalding accidents. A setting of 120° to 125°F is adequate for most domestic use. If you find these temperatures are not satisfactory for automatic dishwashing, you can try raising the thermostat slightly until you find a suitable temperature. Dishwashers now have built-in heaters which can boost the water temperatures to desired heights. This is more appropriate than raising the water temperature for the whole house.

An automatic electric water heater timer can save up to a third of your energy use for hot water. This inexpensive device will usually pay for itself within one year on the savings it provides. The timer allows you to program when the heater is on or off. Why heat water when it is not needed?

Figure 2.

Solar water heaters are cost effective for south Louisiana. They will not provide all of your hot water needs, but should be used as a pre-heater for incoming water to your standard water heater (See Figure 2). Using a heat pump for air conditioning will also produce domestic hot water with a heat recovery unit. The recovery unit is worth the extra cost for most homes because of the extensive use of air conditioning in Louisiana. A water source heat pump is especially effective since the whole unit is inside the house and may be installed close to the water heater tank. Also available are heat pump water heaters that not only heat water, but act as a small air conditioner (See Figure 3). However, this works against you during Louisiana's brief winter season.

Figure 3.

Be conscious of hot water use in your home. A little extra thought into how you use and produce hot water can go a long way in saving energy and money.

ACTIVITY 1:

Ask students to list ways that hot water is wasted in their home. Present the list to your class and let them suggest remedies.

Let students work in groups of four and survey the hot water heating system in the school and suggest ways to improve its efficiency.

INFORMATION CHECK:

Please indicate whether the statements below are TRUE or FALSE.

___1. Heating water is the second greatest energy demand in the home.

___2. One person uses about 15 gallons of hot water every day.

___3. One of the first things to do to conserve energy is to limit your hot water needs.

___4. Energy efficient appliances don't help with lowering hot water demands.

___5. One drop a second from a leaky hot water faucet adds up to 400 gallons a year.

___6. It is important for the hot water heater to be well insulated.

___7. Hot water lines do not need to be insulated.

___8. Sediment build-up in the bottom of the heater tank makes it less efficient.

___9. Hot water needs to be 140°F.

___10. A timer on the hot water heater can save one-third on energy use.

TEACHER'S NOTES:

Have a "P" trap and insulated jacket to show the students.

Activity answers may vary. Examples may include:

1. Dishwashers:

Lower thermostat of hot water heater.

Buy dishwasher with built in heaters.

Run only when fully loaded.

2. Water heaters:

Use proper insulated jacket for the heater.

3. Leaky faucets:

Repair faucet.

Answers to True/False:

1. True

2. False

3. True

4. False

5. True

6. True

7. False

8. True

9. False

10. True

RECOMMENDED READING:

Small is Beautiful. E. F. Schumacker. New York: Harper & Row, 1973.

Natural Louisiana Architecture. Cazayoux, Hebert and Winn. Baton Rouge, LA: Louisiana Department of Natural Resources, 1991.

REFERENCES:

"The Comfort Zone" .....E.J. Cazayoux, USL Monthly Press Release.

Comments or questions to: TechAsmt@LA.GOV

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