How to Maximise Boiler Efficiency to Reduce Energy Use

You know as well as we do that your central heating system plays a huge role in keeping you warm through the cold months. But turning on the heating or running a hot bath to keep the chill off uses more energy, so your bill will be higher throughout the winter.

With the energy price cap rising again at the start of October, you may feel concerned about your next few energy bills. One way to control the cost is to check the efficiency of your boiler and make sure it’s in tip-top condition to run efficiently during the winter.

We’ve got the practical steps you can take to maximise your boiler’s efficiency and stay snug, without breaking the bank.

How efficient is your boiler?

A boiler's efficiency is measured by calculating what percentage of the energy it uses is successfully converted into heat energy, taking into account the extra energy being lost out of the flue. So, a boiler working at 94% efficiency loses 6% of energy to activities that don’t involve heating your home. In money talk, for every £1 you spend on energy, only 6p is ‘wasted’.

The more efficient your boiler is, the less fuel it needs to deliver the same amount of heat. It’s more cost-effective, too. Usually, newer boiler models are more efficient than older ones. For example,a condensing boiler typically loses 10% less energy than aged non-condensing boilers.

Find your new boiler with our interactive tool.

Understanding boiler efficiency ratings

In 2015, the Energy related Products Directive (ErP) replaced the SEDBUK scale, which we’d traditionally used to measure boiler efficiency ratings. Since then, boiler manufacturers, like us, have had to label our products with a rating from A+++ to G. As you’d probably guess, a boiler with an A+++ rating is more efficient than one rated G.

Impressively (but also annoyingly if you’re a homeowner in the market for a new boiler), most modern condensing boilers have an A ErP rating. So, you may want to check the SEDBUK rating of different boilers, too.

What is an SEDBUK boiler rating?

Seasonal Efficiency of a Domestic Boiler in the UK (SEDBUK) measures boiler efficiency as a percentage. It shows how much energy the boiler uses vs how much it wastes when heating a home. A boiler with an SEDBUK of 88% will waste 12% of energy.

What is the most energy efficient boiler?

Any boiler with an ErP rating of A or higher has high efficiency. Check its SEDBUK rating for extra peace of mind - the closer this percentage to 100, the better. Look for a boiler with condensing technology, AKA a condensing boiler. With a large heat exchanger, they’re better at capturing heat otherwise lost from flue gases, which is then used to condense water vapour in the boiler’s exhaust.

How to make your boiler more efficient

If and when you should replace your boiler to a more efficient model depends on the boiler system itself, its service history, and the type of property it’s heating. Most boilers will last around 10 to 15 years, then it’s time to consider an upgrade. Find out what a new boiler installation involves in our blog: How long does it take to fit a boiler?

If you’re reading this with an older boiler, then don’t worry. Read our article to understand how long a boiler lasts and make sure your boiler is running efficiently with our handy steps below.

1. Lower your temperature setting

First up, what’s the most efficient temperature for a boiler to run at? It’s a good question and one that depends on the type you have, plus your Ideal room temperature (see what we did there?).

If you have a combi boiler, you can lower your boiler flow temperature to reduce energy consumption. This is different to setting the temperature on your thermostat. The boiler flow temperature is the temperature of the water that leaves the boiler to go to the radiators. Reducing the flow temperature can promote energy savings and maximise its overall efficiency.

Traditional heating systems were designed for a flow temperature of 80°C. But, they can operate at a lower temperature. It may take a few tries to find the optimum setting for yours. We recommend turning the flow temperature down to around 60°C to start with.

How to reduce the flow temperature on an Ideal boiler

Look for the dial with the radiator symbol.
Turn the dial down until the number on the screen shows the flow temperature you want.
Monitor how your heating runs over the next couple of days. If your rooms are taking a long time to warm up, or they’re not getting warm, then you may need to try a higher flow temperature.
Test how this affects temperature and continue to tweak and test until your home is comfortable.

View all Ideal boiler user guides.

2. Insulate your pipes and cylinder

An easy way to reduce your boiler’s energy consumption is with insulation.

Got space around pipes? Fit foam tubes to reduce heat loss and keep water hotter for longer.
Living in a house with an older hot water cylinder? Insulate it in the same way for the same effect.

Just make sure any insulation you purchase is safe to use - ask a shop assistant when you’re browsing different types of insulation.

3. Book an annual service

It’s not only cars that need servicing to keep them up to scratch. Having your boiler serviced each year will help to keep it in peak operating condition. Wave ‘goodbye’ to minor faults that turn into major problems and have the most efficient boiler on your street.

Annual checks also make sure that your model is optimised to consume energy as effectively as possible. Remember to have your service performed by a Gas Safe registered engineer or OFTEC technician (for oil systems).

Find out more: How often do you need a boiler service?

4. Keep your boiler clean and consider a system cleanse

Having your system cleaned by an expert can help improve your boiler’s efficiency by eliminating sludge, rust, and debris. The system will be flushed, then refilled with clean water and protection chemicals to prevent corrosion.

Tip for keeping new boilers clean: Make sure you have a system filter installed for ultimate cleanliness. For more advice like this, read: Top tips for a healthy heating system.

5. A summer switch on

Most of us only tend to think about boiler efficiency as the cold weather draws in. But there’s plenty you can do year-round to maximise energy and cost savings. Though having the heating on in the summer seems unnecessary, switching it on for 15 minutes a week can:

Reduce the risk of your boiler seizing up
Decrease the likelihood of an expensive breakdown when you turn it back on after months of being off

Boiler energy efficiency, sorted

All that’s left to do is enjoy feeling snug, cosy, and comfortable in your home this winter. If you’ve got any more questions about improving your boiler’s efficiency, please contact our team. And if you’re considering upgrading your system, use our tool to find the right model for your house.