How Do Water Heaters Work? A Complete Guide to Components, Types, and Operation

A reliable water heater is essential in any Columbia home, from Shandon’s historic bungalows to modern Northeast builds. But have you ever wondered how it works?

Your system provides hot showers, clean dishes, and more, but understanding gas, electric, and tankless models can help you:

• Maintain efficiency
• Extend lifespan
• Choose the right replacement

This guide covers key components, water heater types, and how they function.

Basic Components of a Water Heater

No matter the type, all water heaters share key components that work together to heat and distribute water efficiently.

• Storage Tank: A large, insulated container that holds heated water until needed. Most residential tanks range from 30 to 80 gallons.
• Heating Element or Burner: Electric water heaters use heating coils, while gas models use a burner to warm the water.
• Thermostat: Regulates the water temperature, typically set between 120–140°F for safety and efficiency.
• Pressure Relief Valve: A crucial safety feature that prevents excessive pressure buildup inside the tank.
• Dip Tube & Heat-Out Pipe: The dip tube sends cold water to the tank’s bottom, while the heat-out pipe delivers hot water.
  • Corroded pipes in older homes like Elmwood Park and Earlewood can restrict flow and reduce efficiency.
  • Regular flushing or pipe replacements keep systems running smoothly.

How Gas Water Heaters Work

Gas water heaters are popular in Columbia, primarily where Dominion Energy provides natural gas. They heat water quickly using combustion.

• A gas burner ignites, producing heat that warms the water in the storage tank.
• The thermostat monitors water temperature, turning the burner on and off as needed.
• A flue pipe safely vents exhaust gases outdoors.

How Altitude and Climate Affects Gas Water Heaters

Columbia’s low elevation doesn’t significantly impact gas water heaters like in high-altitude areas. However, the city’s hot summers and mild winters still affect your system’s operation.

• Hot summers can increase the demand for cool water, meaning your heater may run less frequently, reducing energy use.
• Water heaters work harder during cold snaps, increasing energy use and wear.
• Older units or poorly insulated tanks may struggle to keep up, leading to longer wait times for hot water.

A simple fix is to insulate your water heater. A blanket can help retain heat, reduce energy waste, and keep your water heater system running efficiently all winter.

How Electric Water Heaters Work

Electric water heaters are a popular alternative for homes without natural gas service. These units rely on two heating elements—one near the top and one near the bottom of the tank.

• The upper and lower heating elements activate separately, ensuring an even heat distribution.
• Thermostats control each element, alternating as necessary to maintain a consistent temperature.

How Tankless Water Heaters Work

Tankless water heaters, which heat water on demand instead of storing it, are popular in space-conscious homes like Shandon and Elmwood Park.

• Flow sensors detect when a hot water tap is turned on, activating the heating coils or gas burner.
• Water is heated instantly as it moves through the system.
• Recirculation systems can be added to reduce hot water wait times, especially in larger homes.

One drawback of tankless models is their limited simultaneous use—multiple people using hot water at once may cause a drop in pressure.

Water Heating Process (Step-by-Step Flow)

All water heaters follow a similar process to ensure a steady hot water supply when needed. Here’s how it works.

1. Cold Water Enters Through the Dip Tube

When you turn on a hot tap, cold water enters through the dip tube, directing it to the tank’s bottom for efficient heating.

• In gas water heaters, the burner at the unit’s base begins heating the water.
• In electric models, heating elements inside the tank warm the water.
• For tankless systems, water enters a heat exchanger, where it is rapidly warmed as it flows through.

2. Heating Element or Burner Warms the Water

Once inside, the water is heated to the temperature set on your thermostat (usually between 120–140°F).

• In gas heaters, the burner ignites, generating heat that warms the tank’s water. A flue pipe safely vents combustion gases.
• In electric models, one or two heating elements (typically located at the top and bottom of the tank) warm the water.
• In tankless units, powerful gas burners or electric heating coils rapidly heat the water as it moves through the system.

This process continues automatically until the water reaches the preset temperature.

3. Hot Water Rises to the Top of the Tank or Flows Through the Unit

Once heated, hot water naturally rises to the top of the storage tank. Since hot water is less dense than cold water, it remains at the upper section of the heater, ready for use.

• In traditional storage tank heaters, this heated water stays in the tank until needed.
• In tankless systems, there is no storage—water is heated instantly and flows directly to your tap when you turn it on.

4. Heat-Out Pipe Delivers Hot Water to Your Home

Finally, when you open a hot water tap, heated water exits through the heat-out pipe at the top of the tank. From there, it travels through your plumbing system to supply:

• Showers and bathtubs
• Kitchen and bathroom sinks
• Dishwashers and washing machines

The cycle repeats as you use hot water, with fresh cold water entering the tank or heat exchanger to provide a continuous supply.

Knowing this process helps homeowners spot hot water heater problems and boost efficiency.

Regular maintenance, insulation, and flushing the tank can extend the lifespan of your unit and keep your hot water running smoothly. If you find yourself in need of hot water heater service, Cassell Bros’ trusted plumbing team has you covered on everything from tankless water heater repair to getting you a quote for water heater replacement.