There are many different types of hot water heaters available in the market. In this article, first we will explore different categories of hot water heaters and then look into specific components of electric hot water heaters.
Categories of water heaters
Energy source: Hot water heaters can use various energy sources such as solar, gas and electricity.
Storage or notank: In the first type there is a tank that can store water. In the notank variety, it is an instant water heater as the water flows through the heater chamber. The low tank variety is normally useful for lower levels of hot water requirements.
Capacity: In case of storage, various tank sizes are available. You need to choose a size suitable for your regular usage.
Cost: There are two aspects of cost. One is the initial cost and the second is the regular maintenance cost. A solar water heater may involve high initial cost but the maintenance cost will be very less. However in case of gas, maintenance cost will be higher (but efficiency also is higher).
Energy efficiency: Gas heaters are the most efficient. However given a particular variety, the efficiency depends upon how the heater is designed. An electrical heater with good thermal insulation can be more efficient than the one which does not have such insulation.
Components of an electric hot water heater
Electric hot water heaters have the following components:
Inlet: Arrangement for connecting cold water pipe entering the tank. Normally this will not be provided with any valve to stop water entry as the water tank should not be empty when the power is on. So the inlet is always on.
Outlet: This is the hot water exit pipe connected to hot water pipe system.
Electric heating element: This is a high resistance coil which creates heat when electric current is passed. This is similar to the element in an electric stove, however in case of electric hot water heater; it is enclosed inside a metal pipe. So the heating element will look like a bent metal pipe of a small diameter.
Electrical inlet: Both ends of the heating element are connected to a electrical cable with a plug for the purpose of providing electrical input to the heater.
Thermostat: A thermostat is to regulate the water temperature inside the water heater. Outside there is a setting (normally in the form of a rotating knob with markings on it) where the temperature can be set. Once this limit is reached, the thermostat cuts of the power supply to the heating element and it again connects the power supply when the temperature falls below certain value.
Indicators: Normally in the form of red and orange colors - red indicates the power is on and the second indicator indicates that and the heating is going on. When the required temperature is reached and the heating stops, the second indicator will go off.
Release Valve: There is a temperature and pressure release valve (abbreviated as T&P Valve) which acts when either the temperature or pressure reaches very high. This is a safety feature and during the situation when the temperature or pressure reaches very high, this valve gets opened and water is released through the valve. When water is coming from this valve, it is not normal and indicates a problem in the heating system.
Corrosion preventive anode: This is another preventive safety feature. Inside the tank one anode, a rod made of magnesium or aluminium is provided. During the heating process when the electrolysis is going on, this anode gets corroded and eaten away instead of the tank material itself. During maintenance checks, this anode should be checked for corrosion and replaced to avoid any damage due to corrosion to the tank.
How the Electric hot water heaters work?
As the inlet water valve is always open, the tank is filled with water all the time. Once the electric power is switched on, the heating element starts getting hot. As the heating element is enclosed in a metal pipe (as explained in the components section above), the surrounding metal pipe as well as the surrounding water receives the temperature and gradually gets heated up. As the hot water is lighter than cold water, the water in the tank automatically gets circulation as the heat builds up. Once the desired temperature, as set by thermostat is reached, the thermostat cuts off the power to the heating element. Again when the temperature drops down a certain value, thermostat automatically connects the power supply to the heating element, again starting the heating cycle. This way the temperature of the water is regulated. Incase due to any problem, the temperature or pressure inside the tank exceeds safe value, the release valve opens and water is released through the valve.
During this operation of electric hot water heaters, the indicator lights glow according the power status. When the power is on, the red indicator is on and when the heating element is getting power, orange indicator also is on.
Selection and care of electric hot water heater
- While buying a new electric hot water heater, look for energy star qualification which is available across many countries in the world. Energy star qualification indicates that the equipment is designed for efficient operation and can save up to 30 per cent of power. In additional, there are tax credits for buying energy star qualified equipment in US and some other countries.
- For a small family, consider a tankless water heater as they occupy less space and can be used for short periods and Tankless water heaters consume less power.
- Lower the thermostat rating to about 115-120 degrees Fahrenheit. As per US Department of Energy statistics, lowering your thermostat by 10 degrees can reduce your power consumption by 3-5 per cent.
- For storage water heaters, look for heat insulation while buying or you can add heat insulation easily later. Insulating the tank can save 25-40 percent of energy consumption. Similarly insulating all hot water pipes can save power consumption additionally.
- Switch or (or install a timer) water heaters when not in use especially during night.
- Drain out water every 3 months to reduce segmentation.