Types of Water Heaters
Within the last few years, a variety of water heaters have become available to consumers. The following types of water heaters are now on the market: conventional storage, demand, tankless coil and indirect. It is also possible to purchase water heaters that can be connected to your home's space-heating system.
Storage Water Heaters
A variety of fuel options are available for conventional storage water heaters electricity, natural gas, oil, and propane. Ranging in size from 20 to 80 gallons storage water heaters remain the most popular type for residential heating needs in the United States. A storage heater operates by releasing hot water from the top of the tank when the hot water tap is turned on. To replace that hot water, cold water enters the bottom of the tank, ensuring that the tank is always full.
Within the storage water heaters there are a few installation types depending on the venting for gas. Atmospheric venting uses a vertical passageway to convey flue gases from your water heater to the outside atmosphere — usually through a chimney or existing vent. Power venting feeds directly from the water heater through the wall and allows more flexibility in installation. Electric water heaters do not require venting.
Terrytown Plumbing can also offer installation of new commercial water heaters. It is best to talk to one of our professionals on what type of heater is best for each particular application as each situation varies.
Inside A Water Heater
A gas water heater is nearly identical to an electric water heater, except that it does not contain the two heating elements, but instead has a gas burner at the bottom, with the chimney running up through the middle of the tank.
A water heater consists of the following parts, as shown in the figure above:
- A heavy inner tank that holds the hot water. Typically, this tank holds 40 to 60 gallons. It has to be able to hold the pressure of a residential water system, which typically runs at 50 to 100 pounds per square inch (psi). The tank is tested to handle 300 psi. The steel tank normally has a bonded glass liner to keep rust out of the water.
- Insulation surrounding the tank.
- A dip tube to let cold water into the tank.
- A pipe to let hot water out of the tank.
- A thermostat to control the temperature of the water inside the tank (Many electric water heaters have a separate thermostat on each element.)
- Heating elements to heat the water (These are the thick electric elements similar to those you see inside an electric oven.)
- A drain valve that allows you to drain the tank to replace the elements or move the tank.
- A pressure relief valve (This is an important safety feature that keeps the tank from exploding.)
- A sacrificial anode rod to help keep the steel tank from corroding.
Demand Water Heaters
It is possible to completely eliminate standby heat losses from the tank and reduce energy consumption 20% to 30% with demand (or instantaneous) water heaters, which do not have storage tanks. Cold water travels through a pipe into the unit, and either a gas burner or an electric element heats the water only when needed. With these systems, you never run out of hot water. But there is one potential drawback with demand water heaters -- limited flow rate. Typically, demand heaters provide hot water at a rate of 2 to 4 gallons per minute. This flow rate might suffice if your household does not use hot water at more than one location at the same time (e.g., showering and doing laundry simultaneously). To meet hot water demand when multiple faucets are being used, demand heaters can be installed in parallel sequence. Although gas-fired demand heaters tend to have higher flow rates than electric ones, they can waste energy even when no water is being heated if their pilot lights stay on. However, the amount of energy consumed by a pilot light is quite small.
Talk to a professional at Terrytown Plumbing to see if this type of water heater is right for you.
Tankless Coil and Indirect Water Heaters
A home's space-heating system can also be used to heat water. Two types of water heaters that use this system are tankless coil and indirect. No separate storage tank is needed in the tankless coil water heater because water is heated directly inside the boiler in a hydronic (i.e., hot water) heating system. The water flows through a heat exchanger in the boiler whenever a hot water faucet is turned on.
A separate storage tank is required with an indirect water heater. Like the tankless coil, the indirect water heater circulates water through a heat exchanger in the boiler. But this heated water then flows to an insulated storage tank. Because the boiler does not need to operate frequently, this system is more efficient than the tankless coil. In fact, when an indirect water heater is used with a highly efficient boiler, the combination may provide one of the least expensive methods of water heating.
