How Does A Combi Boiler Work?

A combi boiler (combination boiler) is designed to heat water instantly for domestic use (in the kitchen or shower), as well as to provide heat into a central heating system.  Hence, this type of appliance is known as a combi boiler to indicate a boiler capable of supplying space heating and domestic hot water.

When hot water is being drawn for use in cooking, cleaning, or bathing, no heat is going into the radiators of the central heating system for space heating.

Here’s how a combi boiler works.  Once receiving a signal from a room thermostat for the boiler to fire up the central heating system, the pump inside the combi boiler fires up.  Water begins to pass through a narrow gap in the pipe creating a pressure differential, and causing the gas valve to open.

Gas is ignited in the main burner.  The heat exchanger holds a limited amount of water, which is heated up rapidly and circulated through the heat exchanger.

When the water temperature reaches 60 degrees centigrade, the thermostatic element expands, the hot water system valve closes, and the heating system valve opens, allowing water to flow to the central heating system.  Upon a demand for domestic hot water, the valves operate in the opposite direction, letting the water pass through to the domestic hot water circuit rather than the central heating system.

Combi boilers are popular in the United Kingdom, and appropriate for small homes or flats for which the hot-water demand is not substantial.  Installation of a combi boiler is easy and cheap because there is no feed tank and storage tanks are not required.

A combi boiler is what a combination boiler is more popularly known as. It is a boiler that takes up very little space. The process of condensation in the case of a combi boiler is highly efficient. It is a very popular choice of domestic and household boilers in the United Kingdom. More than half of the boilers used nowadays in British homes are combi boilers.

A combi boiler is different from other boilers in the sense that there is no need to store hot water in a combi boiler. Hence it saves space in the airing cupboard, which would have otherwise been use to store a cylinder for heating water. It derives its name (combi boiler) from the fact that it is combined within a single compact unit.

There is no cistern for storing cold water either in a combi boiler, unlike in conventional boilers. A combi boiler, therefore, saves both energy and time, and enables the user to enjoy a shower that does not require a pump and yet is more powerful than a shower taken using water which is heated in a regular boiler.

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