Boilers use the most amount of energy among all appliances in the home, so to reduce fuel costs and emissions it is important to choose the most efficient boiler. For you as a buyer, an efficient boiler will waste less fuel when heating your home and use less fuel overall, saving you money. It will give you a warmer, more comfortable home and better control of temperature.
How does a condensing boiler work?
Condensing boilers work by recovering much of the latent heat in the appliance. It condenses water vapour and exhaust gases that are produced when burning gas or oil. The condensed vapour and gases leave the system in liquid form via a drain. Heat that was previously wasted into the atmosphere can now be used to reheat system water.
Boilers need to be highly efficient
According to the Energy Saving Trust, home energy is responsible for over 25% of carbon dioxide (CO2) emissions in the UK. To help bring these emissions down, boilers are required by law to have minimum standards of efficiency, as they are the main factor in overall central heating system efficiency.
A new efficient boiler could save you hundreds
The older your boiler, the more likely you are to be wasting gas and money. Even if it is the most reliable appliance in your home, its inefficiency will be costing you hundreds extra in the long run, up to 30% in energy bills each year for an old boiler installed 15 years ago for example.
Boiler efficiency
Boiler ratings are a measure of thermal efficiency which is the rate at which the heat exchanger converts the energy into usable heat. Energy Output/Energy Input X 100. You will find condensing boilers are the most efficient. They can be up to 94% efficient so are given an A rating.
Boiler efficiency is measured using SEDBUK and more commonly now ErP (since 2015). Building regulations require condensing combi boilers as they are the most efficient and the minimum efficiency requirements are 89.5% according to the latest Boiler Plus regulations. This is shown as a letter grading from A+++ down to G.
Boiler Efficiency Ratings: What are SEDBUK and ErP?
SEDBUK stands for Seasonal Efficiency of Domestic Boilers in the UK. It is an energy efficiency rating scheme helpful for making comparisons between boilers. Two versions are used-2005 and 2009. The main difference between them is that 2009 incorporates seasonal efficiency for summer and winter rather than being calculated at just one point in the year.
Although it has been taken over by the ErP (Energy Related Products) grading system, it is still used today by the industry including manufacturers because it gives a more detailed picture of the efficiency and boilers produced before 2015 are still in most households today.
It is important to note that the percentage score for a particular boiler is different between the SEDBUK and ErP rating. The ErP usually giving a higher percentage as it takes into account efficiencies achieved through additional heating controls. Be careful to compare like for like labelling because the same boiler could show 90% under SEDBUK and 94% under ErP.
When listing the boilers here, SEDBUK grading has been used because this information is readily accessible for all the boilers produced before 2015 and after, so it is a fairer comparison
Best high efficiency combi boilers by manufacturer
The following condensing combi boilers are the best combi boilers to buy. They are some of the most efficient produced by manufacturers today. Even a small percentage difference in efficiency can mean big savings in energy bills.
Ideal Logic C35
Efficiency rating 91%
35kW power output, 14.5 litres per minute hot water flow rate.
Check Boilercentral.com for more features and how to get this boiler
Viessmann Vitodens 111-W
Efficiency rating 90.6%
35kW power output, 18.4 litres per minute hot water rate
Get this boiler at Boilercentral.com with its amazing warranty offer
Vaillant, ecoFit pure 835
Efficiency rating 90.6%
35kW power output, 14.1 litres per minute hot water flow rate
Get a quote to install this boiler from Boiler Guide by clicking on the banner below
Worcester, Greenstar 28CDi Compact
Efficiency rating 90.5%
28kW power output, 11.4 litres per minute hot water flow rate
Available from Boilercentral.com
ATAG i28C
Efficiency rating 90.3%
28kW power output, 11.5 litres per minute hot water flow rate
Available to buy from the Boiler Guide on the banner below to get a quote
Baxi 424 Combi
Efficency rating 90.2%
24kW power output, 9.8 litres per minute hot water flow rate
Get a quote to install this boiler from the Boiler Guide on the banner below
*The information in this article should be used for general guidance only and not as financial advice. Full details are on the link in the footer to our disclaimer page. Always discuss your requirements with a competent and suitably qualified professional before undertaking any work.
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