How Does a Tankless Oil Water Heater Work?

Water Heater Structure

Tankless water heaters are much like traditional water heaters. Traditional water heaters hold a bunch of water in a large, insulated tank. A thermometer inside the tank monitors temperature. The thermometer is attached to a thermostat that keeps the stored water at a constant temperature by turning on and off a device called a heat exchanger.

The Heat Exchanger

In oil and gas water heaters, a heat exchanger is essentially a burner directly under the water tank. This burner heats the bottom of the water tank, which spreads heat into the water. The burned gases and some of the heat from the burner are then vented out of the house through a pipe.

Tank Versus Tankless

In a traditional water heater, the burner must run almost continuously at a low level to keep the water warm even when it isn't being used, wasting a lot of heat. Because the water tank only holds a certain amount of water, when that water runs out you have to wait for it to warm up again. A tankless water heater solves both of these problems by using a much larger burner and no water tank. A flow sensor detects when the warm water pipes turn on and fires up the burner. This burner quickly heats the water as it flows through the heat exchanger. When the hot water turns off again, the burner turns off.