What size boiler do I need for my home?

Boiler in kitchen

If you are looking to have a new boiler installed at home, there are numerous factors to consider before you buy. These include:

  • the size of your property
  • how many people live there
  • how many radiators you have
  • what your water pressure is like
  • how many bathrooms/en-suites are being used
  • the boiler’s location
  • the pressure of your mains cold water
  • and whether you have a power shower.

First and foremost, you must choose a boiler that is the right size to meet your needs. Bigger is not necessarily better – one that is too big is like having a Formula 1 engine in a two-wheel drive car!

If it is too powerful it cannot run on a low enough output and may struggle to get rid of the excess heat, so it keeps switching off and on and the ignition will burn out much quicker. It will also use more gas and generate more emissions, running less efficiently in the process.

Conversely, one that is too small means you will be forever moaning at others in your family for not leaving you enough hot water for your bath or shower!

So which size boiler is best for a flat or small property?

If you have a smaller property or flat with one or two people using one bathroom, you will be better off with a Viessmann combi (or combination) boiler which will heat both your hot water and your radiators.

Around three quarters of properties have a combi-boiler, which also saves space as you do not need a separate hot water cylinder. Instead, the water comes from the cold water main and is heated up.

Another option is the storage combination boiler which has an additional storage tank, or ‘heat store’ hidden within the boiler, which preheats the water and offers a higher flow rate.

Contact us to find out which Viessmann boiler is best for you

Which size boiler is best for a larger house?

If you have a larger property, from three-beds upwards, and a family or larger household, we would recommend a Viessmann System Boiler, such as those in the Vitodens range.

If your property is really large, you may even consider having two boilers, which may cost more initially but will be more efficient in the long run.

Contact us to find out which Viessmann boiler is best for you

Which type of fuel do boilers use?

Viessmann boilers, which are internationally recognised and also recommended by Which?, work with natural gas but we can also provide a conversion kit for LPG. Also ask us about boilers that run on oil. If you’re interested in finding out about renewable energy, please visit our Renewables information section.

How much does a new boiler cost?

Based on the size of your property and your requirements, our friendly team at Clarity Heating will help you choose the right boiler to meet your needs. We will look at the ‘output’ required in Kilowatts (KW) – and choose the most appropriate model from our range of Viessmann domestic boilers, from 29KW to 35KW.

We always recommend you choose the best model that you can afford because it will be cheaper in terms of running costs in the long run.

The cost will also depend on whether you are changing your boiler, like for like, or whether you are upgrading or updating your heating system.

Many of the Viessmann boilers come with a five year warranty, which can be extended to 10 years on the 200W range, and we will even cover the cost of extending it on the 100W range if you use Clarity Heating for supply and installation.

Contact us

For further information about our services, please contact Clarity Heating, or call us on 01353 862315.