What Is the Difference Between a Calorifier and a Boiler?

If you are planning a hot water system for a hotel, hospital, residential building or industrial facility, you may come across two terms that are often used together: calorifier and boiler.

Because both are part of a hot water system, it is easy to assume they do the same job. But they don’t. The simplest way to understand the difference is this:

A boiler generates heat. A calorifier stores and supplies hot water.

In many commercial and industrial applications, the two systems work together. The boiler produces the heat, while the calorifier stores the heated water and makes it available when demand increases.

Let’s take a closer look at how each system works and when you may need these.

What Is a Boiler?

A boiler is a heating system designed to heat water or generate steam. Depending on the type of system, it may use diesel, LPG, natural gas or electricity as its energy source. The heated water or steam can then be used for several purposes, including:

• Domestic hot water generation
• Space heating
• Industrial processes
• Laundry and sterilisation
• Commercial and hospitality applications

In a large hotel, for example, the boiler may provide the heat required to support the building’s hot water system. In an industrial facility, it may also provide steam or hot water for manufacturing and processing operations. The key role of a boiler is therefore heat generation.

For a more detailed look at boiler types and applications, you can explore Cauldron’s commercial boiler solutions.

What Is a Calorifier?

A calorifier is a hot water storage vessel designed to store a large volume of heated water for later use. Unlike a boiler, a calorifier does not necessarily generate heat by burning fuel. Instead, it receives heat from another source.

Depending on the system design, a calorifier can be heated using:

• A boiler
• Heat pump
• Solar water heating system
• Electrical heating elements
• External heat exchanger
• Steam

The heated water is stored inside the calorifier and supplied when required.

This makes calorifiers particularly useful in buildings where hot water demand can change throughout the day. For example, a hotel may experience its highest hot water demand in the morning when hundreds of guests are showering at roughly the same time. A properly sized calorifier helps ensure that sufficient hot water is available during these peak periods.