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Gas-fired condensing boilers not only use supplied energy, but in comparison to older boilers, they utilise thermal energy contained in the flue gas -energy that’s otherwise lost when it exits out of the flue pipe.

The advantages of a gas condensing boiler to older heating technologies:

  • Optimum energy efficiency of up to 98%
  • Significantly less soot during combustion
  • Energy consumption drops by up to 30% compared to an old heating installation
  • Low investment costs, often quick to install
  • Flexible expansion, e. g. with solar collectors, heat pumps, cylinders and controls
  • Suitable for hot water supply as well as heating

A simple guide to the different boiler types

Combination (combi) boilers

'Combi' is short for combination boiler. This type of boiler does two things, it heats water and provides central heating.

Combi boilers heat water as you draw it from the tap. They don't need a water storage tank as the boiler is connected directly to the water mains, meaning it only heats water as and when it's needed. If you are in need of hot water at any time without worry, a combi boiler will likely be the best choice for your home. Furthermore, the lack of a water storage tank means that you’ll save space in your home too.

Homes which suit combi boilers

Combi boilers are cost effective and energy efficient, as well as compact. They don't require a water storage tank (usually in the loft) or a hot water cylinder, making them ideal for properties with limited space. They provide best-in-class energy efficiency Combi boilers are one of the most popular boiler types fitted in the UK today.

Note that for larger households with multiple bathrooms in active use, the delivery of hot water can be affected when more than one hot water tap is in use simultaneously. Furthermore, homes that have poor incoming water pressure and/or flow rates could struggle to efficiently utilise a combi boiler. A certified engineer can assess the viability of a combi boiler in your home during a visit.

For more information, read our complete guide on combination boilers.

System boilers

System boilers also known as sealed system boilers, need a water cylinder to store hot water, however there’s no need for a water tank in the loft, as the heating systems are built into the boiler itself, unlike regular boiler systems. These combine the benefits of a regular open vented boiler with a space-conscious combi boiler.

Homes which suit system boilers

System boilers are ideal for homes with more than one bathroom, as they provide a constant supply of hot water to any number of taps at the same time, yet are space-conscious enough to warrant an internal water tank.

Furthermore, as all the necessary components for the heating system are built into the system boiler itself, this type of boiler is less susceptible to the effects of frost build-up. If you live in a particularly cold climate, where an attic water tank could be negatively impacted, a system boiler would be a better solution for your home’s heating requirements.

For more information, read our complete guide on system boilers.

Regular boilers (open vent)

Regular boilers, sometimes known as open vent, heat-only or gravity-fed boilers, provide central heating and hot water through a hot water storage cylinder. The cylinder is often found in an airing cupboard and the cold water tank is usually found in the loft. Typically, older homes that have traditional heating systems will contain a regular boiler installed.

Homes which suit open vent boilers

If your home has multiple bathrooms, open vent boilers are perfect as they can provide a lot of hot water at the same time. Open vent boilers work well if you are replacing an old open vent heating system, and ideal if water pressure is low in your area. Note that they do require more space than other boiler systems, due to the necessity of a separate water tank - often placed into an attic or loft space.

If your home has particularly old radiators and heating pipework (25 years old+) and a small hot water cylinder in the airing cupboard, chances are you already have an open vent boiler. Open vent boilers work on a much lower system pressure than that of a Combi or System boiler. Combi and System boiler types produce much higher system pressures when operating, this increased pressure can cause leaks and damage when fitted to older systems. If your old boiler has broken down and your system is old, it is often advised to replace it with another Open Vent boiler as they are the cheapest type of boiler to buy and can be changed fairly quickly and easily without having to replace old radiators and pipework.

For more information, read our complete guide on regular (open vent) boilers.

So what is the right heating system for your home?

To find the perfect solution for your home, speak with your local Vaillant Advance heating installer for further advice and support.

An installer will assess your hot water and heating demands, look at your current boiler and then advise on the most efficient and effective Vaillant boiler to ensure it delivers maximum comfort for your home.

Find an installer here

Some useful information

If you're looking to replace your boiler, you may want to seek some advice before doing so. We have set up a guide in what to consider when replacing your heating system.

If you have a good idea of what product you're wanting installed, then check out our guide on how to purchase you're new product.

Boiler replacement

Replacing your heating can help you save up to 30% energy. Discover more

How to buy

Check out our guide on how to buy your new heating system

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