What size boiler do I need for my house?

The size of your boiler will determine how much warmth is emitted throughout your home or space. This will help ensure that you are warm enough and have sufficient hot water at your disposal without creating an expensive energy bill. Below are some factors you should consider, to ensure you choose the right system for your needs. 

Most UK boilers used are what’s called a combi boiler. So, what exactly is a combi boiler? 

A combi boiler system serves both heating and hot water demands from the main water supply. They are practical and low cost to run. They are perfectly efficient for houses with one bathroom. However, for houses with growing families and more than one bathroom, a combi boiler may struggle, as water is heated when needed rather than stored in a tank. This is another aspect to why sizing a boiler is important before installation, as the size can determine what type of boiler you will need. 

Gas engineers use a few methods to size boilers when completing surveys. If you require a new combi boiler, they measure the incoming mains water pressure. If you require a heat only boiler, then the amount or radiators and their size come into consideration, as well as the load of the hot water cylinder. Your engineer should install the correct sized system so that it is the most cost effective and energy efficient, which will help avoid future boiler repairs. 

How is boiler size measured?

It is important to understand how boiler size is measured, before you look at the factors affecting which boiler size and type you should choose to install. This refers to the output of the boiler in kilowatts (kW) and not the physical dimensions of the boiler.  A kilowatt is a unit used to measure how much energy is given from the boiler in the form of heat. The more heat and hot water you require, the higher output you will need

Boiler size calculator

Calculating the best size boiler for your home is crucial. You don’t want a boiler that is too low powered or one that is unnecessarily powerful. It is possible to determine what size boiler you need for your home from these three factors:

  • The number of radiators.
  • The number of bathrooms (with non-electric showers).
  • The number of people in the home (the demand for hot water).

Boiler size for medium (3 bedroom) and large houses?

Usually a 29-35kw is the average size combi boiler used for a three bedroom house with one bathroom and one en-suite. Depending on the size of your home, a 29-35kw combi boiler may still be suitable. However, it all depends on the amount and size of your radiators and the number of bathrooms you have.  A 35-42kw boiler would be installed for a larger house, with a max of 20 average sized radiators and two bathrooms. 

Sizing a boiler can become a complicated job. Therefore, it’s always best to call out a heating engineer to help you with the process. If a boiler is not sized correctly, it can lead to problems with energy efficiency and excessive costs. Make sure you choose the right plumbing company for the job, and everything to do with the operation and maintenance of the boiler has been fully explained to you before they leave. To find out more and book a consultation, get in touch.  

What size boiler do I need for my house

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