Difference between Boiler and Water Heater. In some cases, hot water might only become available in a household after installing specific equipment. This is relevant, for instance, when a residence is located far from centralized supply or when the system only provides cold water. Let’s explore what devices can ensure comfortable living conditions, specifically looking into the differences between a boiler and a water heater.


Boiler – an apparatus that includes a storage tank within its construction.

Water Heater (tankless) – a device that contributes to raising the temperature of the liquid passing through it.


Equipment of these types is commonly used in the discussed supply systems. Essentially, a boiler is also a variation of a water heater. However, unlike other devices of similar purpose, it is equipped with a reservoir. The tank is usually relatively small, but there are models with significantly larger capacities, holding hundreds of liters of liquid.

Water in a boiler can be heated directly by an integrated heating element (usually electric) or other energy sources. Additionally, units with indirect action are often installed, functioning through a heat exchanger. The distinction between a boiler and a tankless water heater lies in the fact that achieving the desired result with a boiler requires waiting for some time.

On the other hand, a tankless device starts delivering hot liquid immediately upon opening the tap. In this case, there is no storage tank. The water simply passes through the heating element, and there is no limitation on its usage. However, a downside is the high energy consumption during device activation. Typically, a separate electrical line is required to use such equipment.

Many see the advantage of a tankless device in its compactness. Indeed, its installation doesn’t demand much space, which is crucial in small areas. However, it’s important to note that these water heaters are sensitive to water pressure in the system. Hence, on the upper floors of tall buildings, their effectiveness might be limited. Equipment with a storage tank doesn’t depend on water pressure.

Considering the difference between a boiler and a water heater, let’s touch upon some additional nuances. For instance, when using a tankless device, it’s important to know that a portion of cold water will go unused each time until hot water flows. Moreover, the liquid’s temperature can fluctuate due to inconsistent water pressure. In this regard, a boiler tends to be more convenient. Such a substantial device is also preferable when multiple points need water supply. However, it should be securely fastened to a very stable surface.