What's The Difference Between A Water Heater, Furnace, And Boiler?

What's The Difference Between A Water Heater, Furnace, And Boiler?

Water Heaters vs Boilers vs Furnaces

Here’s the quick summary:

• Water heaters don’t heat your home. They do provide hot water.
• Boilers use water to heat your home.
• Furnaces heat the air and blow it into your home.

How Does A Water Heater Work?

As cold water enters the tank, the water is heated. If it’s a natural gas or propane water heater, the gas burner is ignited to heat the water. If it’s an electric water heater, there’s a heating element that does the work. As the water heats, it rises toward the top of the tank. The hot water is then dispensed from the top.

While water heaters heat water continuously so it’s ready when you need it, tankless water heaters can provide hot water on demand. Instead of water sitting in a tank, it heats the water rapidly when you need it.



Water heaters handle delivering hot water to your plumbing system, including showers, sinks, washing machines, or dishwashers. They don’t provide home heating.

How Does A Boiler Work?

Boilers, however, use water to provide heat. They typically use gas or electricity to create heat, although some older models use oil. The fuel source is used to heat the water inside the boiler.

If it’s a gas boiler, an electric ignition system will ignite the gas inside the combustion chamber. A heat exchanger transfers the heat to the water, which is then distributed throughout your home. Hot water and steam travel through pipes to radiators or radiant heat pipes underneath floors. Since it’s a closed system, the water travels from one location to the next before returning to the boiler. When it does, the water is reheated and distributed again. An electric boiler works in similarly except it uses electric coils to heat the water.



Most boilers these days do double-duty as hot water heaters.

How Does A Furnace Work?

A forced-air furnace using gas or propane is ignited either by a pilot light or an electric ignition switch. Turning up the temperature on your thermostat or triggering your forced-air furnace to turn on will fire up the burners, which in turn heat the heat exchanger. A blower forces the warm air into the ducts that run throughout your home. When warm air blows into a room, cooler air is sucked into the air returns and sent back to the furnace to be reheated.

Electric furnaces work the same way except they heat the air using electric coils instead of a flame.

What About A Heat Pump?

Heat pumps work a little differently. It uses electricity and refrigeration technology. There are two units: a condenser and an evaporator.

Heat pumps extract heat from the outside air – even in cold temperatures. Liquid refrigerant in the evaporator is turned into gas. Pressure is added to increase the temperature. The hot gas then flows through coils in the indoor condenser. As the heat is released indoors, the gas cools and turns back into a liquid. As the pressure is released, it cools further and is sent back to the evaporator to start the process over again.



One advantage of heat pumps is that they can serve as both heating and cooling units. In cooling mode, the process is reversed.

Which Is Better For My Home: Water Heater, Boiler, Furnace, Or Heat Pump?

• Water heaters heat water. They won’t heat your home.
• Boilers can provide hot water while also using the heated water to warm your home.
• Furnaces and heat pumps heat the air and distribute it through your home.

Which is the best option for you? There are pros and cons to each. You’ll want to consider the installation costs, the monthly energy usage, and your personal preference. Then, sit back, relax, and enjoy a nice warm home.