How Electric Water Heaters Work and Their Types

An electric water heater uses electricity to heat water for domestic or commercial purposes. Three main designs cover the field: normal plate heaters, immersion heaters and geyser heaters. Each works differently, carries its own trade-offs and demands its own safety habits.

What is a Normal Plate Heater?

A normal plate heater is a basic, affordable choice for small amounts of water, such as shaving or washing dishes. Two nickel plates sit roughly 2 mm apart with an insulator between them. The plates connect to a cord that plugs into a wall outlet. When switched on, electric current flows through the plates, which heat up and pass that heat to the surrounding water.

Advantages and Disadvantages of Normal Plate Heaters

The advantages of normal plate heaters include:

• They are easy to use and portable.
• They cost little and are sold almost everywhere.
• They can heat water quickly.

The drawbacks of normal plate heaters include:

• Used incorrectly, they can deliver electric shocks or start fires.
• They warm only small amounts of water at a time.
• They can scorch containers or surfaces they touch.

Safety Precautions for Normal Plate Heaters

Safe use of a normal plate heater calls for these precautions:

• Watch the heater continuously and keep it clear of metal objects and flammable material.
• Never test the temperature with a finger or any other body part.
• Unplug it after use and store it in a dry place.

What is an Immersion Heater?

An immersion heater sits directly in the water it heats. It is a step up from a normal plate heater in both capability and efficiency.

Its metallic body contains a heating element housed inside a capillary tube bent into a U or coil shape. Magnesium oxide packs the tube as insulation. Both sealed ends terminate in a three-pin socket and plug. Element ratings run from about 250 watts to 2 kilowatts depending on heater size.

Advantages and Disadvantages of Immersion Heaters

The advantages of immersion heaters include:

• They can heat large amounts of water in containers or tanks.
• They serve many purposes: bathing, washing and cooking among them.
• A thermostat switch turns the heater off automatically once the set temperature is reached.

The drawbacks of immersion heaters include:

• They cost more and generally last less long than normal plate heaters.
• Careless handling invites shocks or burns.
• Hard water or poor-quality materials corrode or leak over time.

Safety Precautions for Immersion Heaters

Safety precautions for immersion heaters:

• Never switch on the heater without immersing it in water first.
• Never touch the heater or the water when the power is on.
• Always disconnect the heater from the plug socket before removing it from the water.
• Never touch the water-filled container or tank when the power is on.
• Only use clean water for heating and avoid other liquids.

What is a Geyser Heater?

A geyser heater is an electric water heater built around a storage tank where one or more heating elements warm the water.

It also goes by the names storage water heater and electric boiler. Unlike a portable immersion heater, it is a fixed appliance plumbed into the water supply, with a cold-water inlet, a hot-water outlet and a valve controlling flow. Its thermostat cycles the heating elements to hold the stored water near the set temperature. Household models commonly hold anywhere from about 20 to 90 liters, though smaller and larger tanks exist.

Advantages and Disadvantages of Geyser Heaters

The advantages of geyser heaters include:

• They hold a ready store of hot water, so taps deliver it without on-the-spot heating delays.
• Wall or floor mounting follows convenience and available space.
• Insulated bodies slow heat loss and save energy.

The drawbacks of geyser heaters include:

• They cost more and involve more complexity than plate or immersion heaters.
• Scaling and rust call for regular cleaning and maintenance.
• Improper use risks scalding or, in extreme cases, tank failure.

Safety Precautions for Geyser Heaters

Some of the safety precautions for geyser heaters are:

• Always follow the manufacturer’s instructions for installation, operation and maintenance.
• Never tamper with or adjust the thermostat switch or pressure relief valve without professional guidance.
• Always use a circuit breaker or fuse to protect against overloading or short-circuiting.
• Never leave children unattended near the geyser heater or allow them to play with it.

Conclusion

Plate, immersion and geyser designs cover everything from a cup of shaving water to a household’s daily supply. Match the type to the volume of hot water needed, the budget and the installation situation, then follow its safety precautions every time.