Hot Water Heater, The Basics...

The average hot water heater accounts for 25% of the homes' total energy use. With rising energy prices, it just makes sense to learn a little more about these units.

These units have an energy efficiency rating that is referred to as the energy factor (EF). This is a relative rating of the efficiency and ranges from about .5 to 1.0. In simple terms, the higher the EF the less it will cost to operate.

Another rating of these units is their first hour rating. This is a measure of how much hot water the unit can provide in the first hour you turn it on. It takes into account the amount of water stored and how fast it can heat it.

These units are also rated according to their storage capacity. This is the number of gallons of water the units can hold.

Standard units can use gas, electric, oil, geothermal, or the sun to heat the water. The energy source you choose should be based on the price and availability of the energy source as well as up front cost.

They all operate in the same basic way. A thermostat senses the temperature of the water inside the tank. It turns the fuel on and off as required to maintain a set temperature. That temperature is adjustable to suit the tastes of the customer.

These units have some added components for safety and to make them last longer. First, they have a safety feature that is called a temperature/pressure relief valve. This is a valve that opens to relieve the pressure in the tank in case of a malfunction. The outlet of the valve is piped down to within a few inches of the floor. This is to prevent injury and damage if the valve opens. The water released when the valve opens will be extremely hot and may flash to steam.

Another safety feature that has been implemented in the United States is called flammable vapor ignition resistant (FVIR) technology. This is basically design features that are integrated into a hot water heater to prevent flammable vapors such as gasoline in a garage from entering the unit and igniting. The technology usually includes three parts. The first part is called the flame arrestor plate and allows combustion air to enter the unit while preventing flames from escaping downward and igniting vapors. The second part is typically called a thermal cutoff switch. This is a temperature sensor located near the burner that opens to shut the gas off. This will usually occur when adequate combustion air is not available. this will cause the burner flames to droop and the cutout to open. The final part is usually a LDO screen. This is basically an air filter that is installed to prevent the combustion air openings from becoming clogged by lint, dust, and oil. **HOT TIP** If your unit has this feature, the screen will require periodical cleaning.

Most storage units have what is called a sacrificial anode. This is a metal rod that is suspended in the tank. Minerals that are naturally in the water interract with metal and can eat away the metal. This anode provides a place for the reaction to occur without damaging the tank.

Indirect fired units are tanks which are usually connected to the homes' central heating system. They contain a heat exchanger which separates the potable water from the heating source water.

Both of these types of hot water heaters have one big disadvantage. That is that, as the tank of water sits in your home, it cools off. This is referred to as stand by heat loss. Then the heater has to turn on to heat the water back to temperature. This wastes energy dollars!

If the insulation value on your tank is less than R-24, it is a good idea to install a water heater blanket. This will help to minimize the standby losses and therefore save you money. Water heater blankets are available in many stores or you can even make your own. If you purchase one, get one with at least an R-8 insulation rating.

If you have an electric unit, you can also install a timer that will help to lower the standby losses. The timer is set to only maintain the water temperature at specific times during the day. They are available at many hardware and home improvement stores for less than $50. The timers can save you 5-10% on your water heating costs which will pay for the timer very quickly.

You can increase the efficiency of your water heating system by adding a solar water heater or a drain water heat recovery system. In warmer climates, a heat pump water heater can be used to increase the efficiency of your electric hot water heater. These systems combine an air source heat pump with your existing water heater. When the thermostat on the water heater senses the need for heat, the heat pump is energized. The heat pump utilizes a refrigerant system to remove heat from the air in the home and deliver that heat to the water in the tank. These units provide between 1/2 and 3/4 of a ton of air conditioning as an added benefit.

These systems use a flow sensor and a temperature sensor. When the unit senses the flow of water, it checks the temperature and turns on the heat as required. The heat can be produced by burning gas or oil, or with electricity.

The latest innovation is a microwave hot water heater. These units use the same technology that is found in a cooking microwave to provide hot water on demand.

These units are rated by their efficiency, heat input rate, and the amount of water flow. It is very important to select the proper size unit.

Some of these units are a part of the homes' heating system. They are referred to as combination boilers or combi boilers for short.

These units are often used at a sink where they are mounted in the cabinet below. Their main advantage is that water is not wasted while waiting for it to heat up. The units without a tank are a little bit more efficient because they only heat the water as it is needed.