Boiler Types Explained – Combi, Regular and System

When you are interested in replacing your old boiler, you might come to realise there are three different types of boilers. These are combi, regular and system boilers. This can make the process of buying a new boiler a challenging prospect. However, this guide will take you through the unique qualities of each boiler type, helping you to find the best fit for your home.

A combi boiler is a single unit that provides hot water and central heating for the entire household. This type of boiler heats water with the use of an internal heat exchanger directly from the cold mains, providing hot water on demand.

As combi boilers can heat water instantaneously, there is no need for hot water cylinders. Alongside, combi boilers’ compact size, getting rid of these old water cylinders will create more living space inside your property.

Combi boilers also prove to be energy-efficient, as hot water is supplied only when you need it. Therefore, energy is not wasted by constantly having to heat up a tank full of water. This not only allows you to save money on your energy bills, but it also reduces the carbon footprint of your property.

Since combi boilers source all their water supply from the mains, this type of boiler will struggle to meet a high demand for water. This means combi boilers are a more suitable option for smaller households, that have a relatively low demand for water. This is not to say, combi boilers cannot provide an adequate supply of water for larger households, although, if water is needed for multiple taps at once, the water pressure will dramatically reduce.

A regular boiler, otherwise known as a conventional boiler, provides both heating and hot water with the use of an additional tank and hot water cylinder. Cold water from the tank is heated up in the hot water storage cylinder, which feeds into the household’s taps. Regular boilers are either sealed or open vented. In sealed systems, the boiler does not have a feed and expansion tank, making it closed to the atmosphere. However, open vented systems are open to atmospheric pressure and do have a feed and expansion tank, helping to accommodate water loss from leakage or evaporation. The water tank in the loft maintains the right water level whilst a pump circulates the hot water to the radiators.

The primary advantage of installing a regular boiler is its ability to produce high volumes of water to multiple places at once. Therefore, a regular boiler is more suitable for larger households than a combi boiler, as it can supply a consistent water flow to several bathrooms at the same time.

Regular boilers are not ideal for small homes, as you need a loft for the cold water tank and an airing cupboard for the hot water cylinder. Also, regular boilers do not tend to be very efficient, as the hot water stored in the cylinder can lose heat over time. Although, it is possible to stop this from happening, by properly insulating the cylinder.

System boilers are essentially modern versions of regular boilers. They operate with the use of a hot water cylinder, however, they come without the need for a water tank in the loft.

The process occurs when water travels directly from the mains to be heated in a single storage cylinder. This water is then distributed to radiators, taps and showers.

To begin with, system boilers are usually easier to install than other types of boilers, as most of the components for the central heating and hot water systems are built into the boiler. Equally, they do not need a cold water tank, therefore, owning a home with a loft is not necessary to have a system boiler.

Unfortunately, system boilers only heat water in advance, meaning that you will need to set a timer for your boiler to get hot water for when you typically require it. The hot water tank of a system boiler can only hold a certain amount of water, therefore, if you use an excessive volume of hot water at once it may end up running out.