Basics of Water Heater: Types,...
March 6, 2025
Basics of Water Heater: Types, Key Components, and How it works
Introduction of Water Heater
Water heater is an essential part of the domestic water system. It is used in most modern households, providing
hot water for bathing, cleaning, cooking, and heating. Water heaters work by using energy like electricity, gas, or
other source to heat the water. In this blog, we will explore the different types of water heaters, their key
components, and how they work.
What are the types of Water Heaters?
There are several types of water heaters available according to their shape, sizes, uses, function, etc. It is
essential to choose the right water heater as per requirements. Below listed are the common ones:
1. Storage Tank Water Heaters: These are the most common type of water heater used in households. They consist of an insulated tank that stores and heats a specific amount of water to fulfill the need.
2. On-demand or Tankless or Instantaneous Water Heaters: These water heaters operate as a stand-alone system and eliminate the requirement for a storage tank. Since this type of water heater only heats the water when needed, it is usually more energy efficient than the storage tank water heater.
3. Heat Pump Water Heaters: These water heaters not only heat the water but also condition the air and dehumidify the space around them. They have a higher purchase cost than traditional electric water heaters but are more energy-efficient and can save money in the long run.
4. Solar Water Heaters: This system includes solar collectors, storage tanks, and a backup system for cloudy days. Solar panels collect and convert the sunlight into heat, which is then used to heat the water. These water heaters are environment friendly and can reduce the energy cost.
Key Components of Water Heater
1. Tank: It is the main part of the water heater and is usually made of steel with a glass lining to prevent corrosion. The tank holds and stores the water and keeps it hot until needed. Insulating material like polyurethane foam is used to cover the exterior of the tank. Tank sizes typically range from 20 to 80 gallons or more depending upon the hot water needs. Tankless heaters don’t have a storage tank.
2. Inlet Pipe, Dip Tube, and Outlet Pipe: The inlet usually located on the top of the tank is used to send the cold water inside the tank. The dip tube ensures the incoming cold water is flowing toward the bottom of the tank to allow the hot water to stay at the top for use. The outlet pipe allows the hot water to leave the water heater.
3. Anode Rod: This rod is suspended inside the tank and helps prevent corrosion by attracting minerals that would otherwise rust the tank. The magnesium anode rod is best used in soft water situations while an aluminum anode rod is best for hard water.
4. Heating Element or Burner: In electric water heaters, heating elements heat the water. In gas heaters, a burner at the bottom of the tank does the job.
5. Thermostat: This device controls the temperature of the water by regulating the heating elements or burner. Water heaters are designed to output water at 140⁰F and can be set to individual preferences with the thermostat. Often, a range of between 115⁰F and 120⁰F is safer and more energy efficient.
6. Temperature and Pressure Relief Valve: This valve is a safety device and is an essential component in case of excessive pressure or temperature buildup inside the tank. If the pressure or temperature exceeds the safe level, the valve opens and releases hot water and pressure, preventing potential tank damage.
7. Drain Valve: This valve is located near the bottom of the tank in many water heaters. It allows users to periodically drain and remove sediment buildup in the tank, which can affect the heater’s efficiency.
How do Water Heaters Work?
Let’s understand the working of water heaters by considering storage tank type vs tankless type.
1. Storage Tank Water Heaters
Water is stored in a large insulated tank and kept at a set temperature. As hot water is used, fresh cold water enters the tank to be heated.
- Filling the Tank: Cold water enters the tank through the cold-water inlet.
- Heating the Water: The thermostat detects the water temperature. When it falls below a preset level, it activates the heating element (electric) or gas burner (gas).
- Heat Transfer: The heating element or burner heats the water in the tank. In electric heaters, the coils heat up and transfer heat to the water. In gas heaters, the burner ignites and heats the water through a heat exchanger.
- Hot Water Availability: Once the water reaches the desired temperature, the thermostat turns off the heating element or burner. Hot water is then available for use through the hot water outlet.
- Maintaining Temperature: The tank is insulated to minimize heat loss, and the thermostat continuously monitors the temperature to maintain it.
- A hot water return system, also known as a hot water recirculation system, helps provide instant hot water to the fixtures by circulating hot water continuously through the pipes. It is used in places where the water heater is located far from the faucets, it can take a long time for hot water to reach the taps.
- A dedicated return line is installed from the furthest hot water fixture back to the water heater. This allows hot water to circulate continuously in a loop. A pump is installed on the hot water return line, typically near the water heater. The pump moves hot water from the farthest fixture back to the water heater.
2. Tankless Water Heaters
Heats water on demand, without storing it. As water flows through the unit, heating elements or burners heat it instantly.
- On-Demand Heating: When a hot water tap is turned on, cold water flows into the unit.
- Activation: The flow sensor detects the water flow and activates the heating element.
- Heating Process: The water is heated as it passes through the heating element. This can be done using electric coils or gas burners.
- Instant Hot Water: The heated water is delivered directly to the tap, providing hot water on demand without the need for a storage tank.
- Energy Efficiency: Tankless water heaters are generally more energy-efficient than tank-type heaters because they only heat water when needed, reducing standby heat loss.
Maintenance and Efficiency Tips
- Flush the Tank Annually: Sediment buildup can reduce efficiency and lifespan. Drain the tank completely and flush it with water to remove sediment.
- Inspect the Anode Rod: Check the anode rod every 2-3 years. Replace it if it’s heavily corroded to prevent tank rust.
- Test the Pressure Relief Valve: Lift the valve’s lever and let it snap back. If water doesn’t flow out, replace the valve.
- Check for Leaks: Regularly inspect the area around the water heater for any signs of leaks.
- Set the Right Temperature: Keep the thermostat at 120°F (49°C) to save energy and prevent scalding.
- Insulate the Tank: Use an insulating blanket to reduce heat loss, especially if the water heater is in a cold area.
- Install Heat Traps: These can prevent heat loss through the pipes and improve efficiency.
- Use a Timer: For electric water heaters, a timer can help reduce energy usage by turning the heater off during non-peak hours.
- Clear the Area: Keep the area around the water heater free of clutter to ensure proper ventilation and safety.
- Know How to Shut Off: Familiarize with the shut-off valve and the power supply in case of emergencies.
Conclusion
Water heaters are indispensable appliances in modern households, providing hot water for various domestic needs such as bathing, cleaning, cooking, and heating. Each type of water heater offers unique advantages tailored to specific requirements and preferences. Familiarizing with the essential parts, such as the tank, heating element, thermostat, and anode rod, can help to maintain the water heater effectively and ensure its efficient operation. Regular maintenance and selecting the right type of water heater can lead to significant energy savings and a reliable supply of hot water for the household.
