Central Heating Boiler Systems

Each home is different and every household has varying requirements, which is why one boiler type won’t suit every property or family. But it’s important that you choose the right type of boiler so you don’t have to worry about running out of hot water, low water pressure or heightened energy bills.

Types of boiler systems

Below, we’ve summarised the main types of boiler systems, covering information such as how they work, which home they suit best and the pros and cons of each.

Conventional (or heat only) boilers

Conventional boiler systems, sometimes also referred to as heat only boilers or regular boilers, are made up of multiple components in order to work effectively. Not only is there the gas boiler unit itself, but there is also a cold water tank (generally located in the loft) to draw in fresh water via the mains and a hot water tank that is able to store the heated water for a period of time. The water that is kept in the tank can supply your taps and hot-water appliances and the remaining hot water is circulated around the radiators to heat your home.

Conventional boilers are most commonly powered by natural gas, but there are other fuel types available, including LPG, electricity and oil. In a conventional gas boiler, the gas is burned in a combustion chamber to heat it up before it’s looped through a series of pipes. Cold water surrounds these pipes within the heat exchanger, which also heats up as the hot gas moves through the pipework. Once the water is heated, it can be sent to the water tank for storage or pumped around the radiators. As it gradually cools down, it’s sent back to the boiler for reheating and the entire process starts again.

Pros and cons of a conventional boiler

These boiler types are ideal for large homes that have an increased hot-water demand. If you need to run multiple showers or appliances all at once, then a conventional boiler will likely be the best option for you, offering no significant loss of pressure when this is the case. They’re also ideal for homes that have low water pressure in the first instance.

However, as we’ve already mentioned, these systems can take up a lot of space between the boiler and both the hot and cold water tanks. Running out of hot water is also a potential problem. Once you’ve used up what’s in the hot water tank, you’ll need to wait for the boiler to heat more, which could take over 30 minutes. For this reason, it’s a good idea to have a high-quality smart thermostat system that will allow you to schedule your heating from your phone or control it remotely.

Combi boilers

Conventional boiler systems were always the most popular, until recent years, when the combination boiler has overtaken and been driving the market since. It’s obvious why they’re so popular when you start to look at some of the benefits of a combi boiler, including the fact that you never have to run out of hot water again and your heating and hot water can all be delivered from a single unit.

A combi boiler provides heating and hot water on demand rather than storing it in a tank for later. This means you only heat the water that’s actually needed, rather than heating lots of water that may sit in the storage tank, unused. They work in much the same way as a conventional boiler, burning gas to heat up the water, and are up to 98 per cent efficient.

Pros and cons of a combi boiler

Combi boilers are best suited to smaller homes not only because of their compact size, but also because you won’t need a cold water tank in the loft or a hot water tank/airing cupboard. Their ability to heat water on demand means you can jump in the shower or wash the dishes whenever you please, without needing to wait for some water to heat up first.

However, these systems do have some drawbacks. Pressure may be reduced when two or more water appliances are on at the same time, such as a shower and washing machine, or tap and dishwasher. Therefore, if you live in a large property and want to run multiple showers or appliances at the same time, a combi boiler may not be the right choice for you. Pressure can also be low in general if your mains pressure is weak.

Check out our separate guide for more combi boiler pros and cons.

System boilers

System boilers are fairly similar to conventional boilers, but they don’t require a cold water feed in the loft because fresh water is supplied directly from the mains supply. This means that they sit directly between a combi boiler (which has no tanks) and the conventional boiler (which has two tanks).

Pros and cons of system boilers

Because these types of boilers have a hot water tank, they can cope with high heat demands and will supply multiple appliances at once. There is no need for a cold water tank, either, which may free up some space in your loft.

The main con of these systems is that the pressure they give out will depend on the mains pressure that goes into your home. If the mains pressure is low, these boilers won’t be able to increase it because they don’t have a cold water feed in the loft.

Condensing vs. non-condensing boilers

While not exactly a type of boiler in itself, this terminology will likely crop up as you’re looking at boiler types. The good thing is you no longer have to choose - all modern boilers now use condensing technology as standard, because they’re more efficient.

In a non-condensing boiler, all the waste gases are expelled via the flue, but a condensing boiler can reuse some of the heat from the waste gases to warm up cold water, increasing their efficiency and reducing the amount of waste caused by these systems.