Types of Boilers - Different Boiler Types Explained

When it comes to types of boilers in the UK, there are three main options that most homeowners and landlords rely on: combi, system and conventional boilers. Each one delivers central heating and hot water in its own way, and the right choice comes down to your property size, the number of bathrooms you have and how much hot water your household uses every day.

At PlusHeat we install and replace boilers nationwide, so if you are thinking about an upgrade we can help you weigh up the options without any pressure.

What Are the Main Types of Boilers in the UK?

The main types of boilers in the UK are combi, system and conventional boilers. These three cover the vast majority of homes connected to the gas grid, and all new models are condensing boilers with high efficiency ratings. Your existing pipework, space available and hot water demand will usually point you towards one type over the others.

Combi Boilers

Combi boilers are the most popular choice in modern UK homes because they heat water directly from the mains supply as soon as you turn on the tap or the heating. There is no separate hot water cylinder or cold water tank, which makes them compact and straightforward to fit.

Pros and Cons of Combi Boilers

Pros

• Saves valuable space with no need for extra tanks or cylinders
• Delivers hot water on demand so you never run out
• Usually cheaper and quicker to install than other types
• Highly energy efficient because it only heats what you need

Cons

• Can struggle to supply multiple taps or showers at the same time in larger homes
• Needs strong mains water pressure to perform at its best
• Not ideal if your household has very high hot water demand

Efficiency of Combi Boilers

All new combi boilers achieve A ratings and deliver between 90 and 94 percent efficiency. They recover heat from the flue gases that older models simply wasted, which helps keep your energy bills lower while staying kind to the environment.

Unit Costs and Installation Costs for Combi Boilers

A new combi boiler unit typically costs between £500 and £3,000 depending on the brand and output size. When you add professional installation the total usually falls between £1,800 and £3,500 for a straightforward replacement. Prices can vary if pipework changes or a power flush is needed, but combi systems generally work out more affordable upfront than the other types.

Maintenance and Servicing for Combi Boilers

An annual service by a Gas Safe registered engineer keeps your combi boiler safe and efficient. These models have a few extra components such as the diverter valve, so regular checks help prevent small issues from becoming expensive repairs later on. Most manufacturers offer warranties of up to ten years when you service the boiler every year.

Suitability for Different Property Types

Combi boilers suit small to medium sized homes, flats and properties with one or two bathrooms really well. They are perfect for couples, small families or anyone who wants to free up cupboard space in a modern house.

System Boilers

System boilers work alongside a separate hot water cylinder, usually tucked away in an airing cupboard. They draw water straight from the mains to fill the cylinder and do not need a cold water tank in the loft, which makes them cleaner and simpler than older setups.

Pros and Cons of System Boilers

Pros

• Excellent hot water flow for homes with two or more bathrooms
• Consistent supply even when several taps run at once
• No loft tank required so you gain extra storage space upstairs
• Easy to combine with solar thermal panels or other renewables

Cons

• Needs space for the hot water cylinder
• Slightly higher installation cost than a combi boiler
• The cylinder can lose a small amount of heat if not well insulated

Efficiency of System Boilers

Just like combi models, new system boilers are condensing and A rated with efficiency levels of 90 to 94 percent. The stored water stays hot for longer, which can actually reduce how often the boiler fires up during busy periods.

Unit Costs and Installation Costs for System Boilers

The boiler unit itself ranges from around £1,800 to £2,800. Full installation including the cylinder usually totals between £2,500 and £4,500 depending on your existing pipework. It is still a worthwhile investment for properties that need reliable hot water all day long.

Maintenance and Servicing for System Boilers

Annual servicing remains essential. System boilers tend to have fewer moving parts than combi models, so they can feel more straightforward to maintain over the years. The cylinder also benefits from occasional checks to keep scale and sediment under control.

Suitability for Different Property Types

System boilers work brilliantly in medium to large family homes with multiple bathrooms or high hot water demand. Landlords often choose them for rental properties because they keep tenants happy with steady pressure and plenty of hot water.

Conventional Boilers

Conventional boilers, sometimes called regular or heat only boilers, are the traditional choice. They need both a hot water cylinder and a cold water storage tank in the loft to feed the system using gravity.

Pros and Cons of Conventional Boilers

Pros

• Ideal for older homes that already have the tank and cylinder in place
• Reliable performance even with low mains water pressure
• Can cope with very high hot water demand across several outlets
• Straightforward to repair using familiar components

Cons

• Takes up the most space with both cylinder and loft tank
• More pipework means a longer and more involved installation
• Older style systems can be less efficient if not upgraded properly

Efficiency of Conventional Boilers

Modern conventional boilers are also condensing and A rated, reaching 90 percent efficiency or higher. Upgrading from an old non condensing model can make a noticeable difference to your heating bills.

Unit Costs and Installation Costs for Conventional Boilers

Units start from around £600 and go up to £2,500. Full installation costs typically range from £2,500 to £4,500 or more if you are updating pipework or removing an old tank. If your home already has the right setup the price stays closer to the lower end.

Maintenance and Servicing for Conventional Boilers

Annual Gas Safe servicing is just as important here. These boilers have a simple design that many engineers know inside out, which often keeps long term repair costs reasonable.

Suitability for Different Property Types

Conventional boilers suit older properties, larger detached homes or any building where the existing loft tank and cylinder are already in good condition. They are a practical choice when you want to keep the original system layout.

What Other Types of Boilers Can You Consider in the UK?

While the three main types cover most homes on the gas grid, you have other options if you are off grid or looking for lower carbon choices. 

• Oil and LPG boilers work in a similar way to gas models but use delivered fuel stored in an external tank. 
• Electric boilers are compact and emission free at the point of use, though running costs can be higher unless you have cheap off peak electricity. 
• Biomass boilers burn wood pellets or logs and can be a renewable route for larger rural properties, but they come with higher upfront costs and need space for fuel storage. 

Each alternative has its place depending on your location and budget.

How Can PlusHeat Help You Choose the Right Type of Boiler?

Choosing the right type of boiler does not have to be stressful. At PlusHeat we specialise in new boiler installation and replacement nationwide.

Whether you are a homeowner ready for a more efficient system or a landlord wanting to improve your rental property, we make the whole process smooth from the first quote to the final handover. Request your free new boiler quote from PlusHeat today and let us help you find the perfect heating solution for your home.

Frequently Asked Questions 

How long can I expect a new boiler to last?

Most modern boilers give you between ten and fifteen years of reliable service, although system and conventional models sometimes reach twenty years when looked after properly. Factors like water quality and how often you service the unit make a big difference.

What should landlords consider when selecting a boiler type for rental properties?

Landlords often focus on reliable hot water supply, good energy performance for the EPC rating and straightforward maintenance that keeps running costs predictable for tenants. A system boiler frequently strikes the right balance for multi occupant homes.

Can you convert from one boiler type to another?

Yes, many homes switch from a conventional boiler to a combi or system setup. The work involves removing old tanks or adding a cylinder and can take one to three days depending on pipework changes. A professional survey will show exactly what is needed.

Are electric boilers a realistic alternative to gas models?

Electric boilers suit properties without mains gas or for homeowners who want zero emissions at the point of use. They are compact and quiet but work best in smaller homes because electricity tariffs are usually higher than gas.

How does the choice of boiler type affect my home energy performance certificate?

A new high efficiency boiler of any type can improve your EPC rating, which matters for selling or renting. Combi and system boilers often deliver the biggest uplift in smaller to medium properties because they reduce heat loss from stored water.