Combi boilers: Everything you need to know

What is a combi boiler – and how does it work?

A combi – or combination – boiler is a single, compact unit that functions as both a water heater and a central heating boiler. This space saver heats water immediately, rather than heating and storing, which removes the need for a bulky hot water storage cylinder or cold water storage tank, as found with old boiler systems.

How a combi boiler heats water

To provide hot water, combi boilers are on constant standby and connected to the mains water supply. When a tap is turned on, the boiler is triggered into action and it heats the water through a heat exchanger, for on-demand hot water any time of day.

How a combi boiler provides central heating

A combi boiler follows the same heating process as a conventional boiler, but the expansion tank is contained in the boiler itself, so water is heated within the boiler before being sent to the radiators.

A conventional boiler has a separate expansion tank to heat water – usually in a house’s loft – and is connected to the boiler using an external feed, which takes up quite a lot of space.

How does a combi boiler compare to other types of boilers?

There are two other main types of boilers besides the combi version; system and standard boilers.

What are the benefits of a combi boiler?

Space saving is a real perk of this boiler system. Rather than requiring room for large water storage cylinders or tanks, combi boilers are compact, making them ideal for many living in a smaller space such as a flat, or anyone looking to save room in their loft.

As there are fewer pieces to the boiler, you have a much lower risk of your pipes freezing, which can be a major concern in winter. This also means combi boilers are typically quicker and easier to install than standard boilers, as there are fewer parts to fit.

Are there any disadvantages of a combi boiler?

If you have a large, busy household with multiple bathrooms, you could lose water pressure, depending on the mains pressure in your area. You should check the pressure levels in your area before choosing your boiler type.

The nature of the combi boiler means all of the heating takes place within one central unit. Because of this, the unit must prioritise certain actions, meaning when the hot water is turned on, the central heating will be paused. It should, however, automatically switch back when hot water is no longer needed.

How much does a combi boiler cost?

The price of a combi boiler differs depending on the brand, size, output and maximum flow rate. The more powerful the boiler, the more it’s likely to cost. Rather than trying to cut costs, you’ll need to choose your new boiler based on the requirements of your home.

Combi boilers come in various outputs with a 24kW model being suitable for small homes such as flats and very small houses. A 28kW boiler costs slightly more and would suit a medium-sized home such as a semi-detached house.

If you have a large home such as a big detached house, you’ll likely need a boiler with a 35kW to 42kW output, which is more costly.

At Help-Link, we offer three of the most reliable and efficient brands on the UK boiler market: Worcester Bosch Group, Vokèra and Ideal. So, whatever size or price you have to pay, you can be guaranteed an excellent, energy efficient and long-lasting boiler.

How much does it cost to install a combi boiler?

Installation costs might fluctuate depending on the type of work needed. Never be tempted to try and save money by installing one yourself – any new boiler must be installed by a Gas Safe registered engineer.

If price is important to you when buying a new boiler, it’s best to work out which type will be the most cost effective with regards to installation, as well as in the future.

In some cases, switching a like for like boiler (e.g. combi boiler for combi boiler) could be the cheapest option when replacing your system, but not always.

Bottom line: do a little research and ask for quotes on a few options.

Get in touch today and we can provide you with a personalised quote for your boiler installation. Along with a professional, friendly service, you’ll also receive a manufacturer backed warranty, and the opportunity to purchase a Customer Care Package, which includes unlimited callouts, a 24/7 care line, and more.