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Boiler efficiency

Discover how to keep your boiler running efficiently, so you can stay warm – and even save money on your energy bills.

What is an efficient boiler?

An efficient boiler is one that runs to the best of its ability, using the least amount of energy (and money) to keep your home warm and cosy.

An inefficient one does the opposite. It uses more energy than it needs to, costs more to run – and can leave you with lukewarm radiators and no hot water.


What types of boilers are there?

There are 3 main types:

  • Combi.
  • Conventional.
  • System.

Let’s look at each one individually.


A combi boiler is designed to give you instant hot water, and heating through your central heating system. Whenever the temperature in your home drops below the level you’ve set, the thermostat sends a signal to the boiler to fire up and heat the radiators.

Similarly, the moment the hot tap or shower is turned on, water inside the combi is heated and sent to that tap or to the shower.


System boilers come with a water cylinder, which usually sits in your airing cupboard, but they don't have a water tank. They pump hot water to the radiators and a sealed hot water storage cylinder. They’re the best choice if you have more than one bathroom or need lots of hot water.


Conventional (also known as traditional) boilers send hot water to your radiators and a hot water cylinder. You turn the tap or heating on, and hot water runs to that tap or to the radiators until the cylinder is empty. Then you have to wait for the boiler to heat the cylinder again.


How can I make my boiler more efficient?

Here are 4 top tips to keep your boiler and central heating system ticking along nicely.

Tip 1: Get a routine service

Just like a car, your boiler needs regular servicing to keep it running smoothly and safely. It can help make it more efficient, detect whether something is wrong - and prevents small issues turning into big problems.

So always book a boiler service with a Gas Safe registered engineer – every year. If you're an OVO customer, you can benefit from a free annual service (in your first year) when you take out cover with OVO HomePlan1

Tip 2: Top up the pressure

Low pressure is bad news for a boiler’s efficiency and energy bills. Equally, high pressure can prevent it from working properly. So make sure it’s in the sweet spot – between 1 and 2 bars of atmospheric pressure.

Tip 3: Insulate your pipes

Lag your central heating pipes with foam tubes from a DIY store – they’re easy to fit and you can do it yourself. It’ll reduce heat loss through the pipes, meaning your boiler doesn’t have to work quite so hard.

Tip 4: Run your heating every month

Pop your heating on for 15 minutes every month right through the year – even when it’s hot outside. Doing this might feel a bit odd, but it’ll keep things active and avoid any problems during winter.

Could insurance help my boiler's efficiency?

It will also give you peace of mind that you'll be covered if anything goes wrong. You simply pick a level of cover, an pay a monthly amount. It's as easy as that. 

Make the most of being an OVO customer and check out exclusive offers at MyOVO.

When should I get a new boiler?

Your boiler is one of the hardest-working appliances in your home. But you don’t really think about it – unless the heating breaks down or your hot water runs cold.

While regular servicing and maintenance will keep your boiler working efficiently for longer, the time will always come when you need to replace it. Sometimes it’s sensible to do that sooner rather than later, as old boilers can be expensive to run.

The Energy Saving Trust, a leading and trusted organisation helping people save money, offers loads of information on boiler and home efficiency. And it's even calculated how much money you could save each year, depending on your boiler’s age and efficiency rating.

Believe it or not, you could save up to £3152!

4 warning signs that you might need a new boiler

Sign 1: Your house and hot water isn’t that warm anymore

If your radiators take too long to heat up or your water doesn’t come through as hot as it used to, it might mean your boiler is on its way out, or indicate another problem, such as a blockage or sludge in your system.

Sign 2: Your heating bills have gone up

One indication that your boiler might need replacing is your heating bills are higher than normal. That’s because boilers become more inefficient and costly to run as they age.

Look for the ErP energy label to see how efficient yours should be. This handy indicator gives boilers a rating from G (lowest efficiency) to A+++ (highest efficiency).

Nearly all modern gas condensing boilers get an A energy rating - or higher.

Sign 3: Your boiler is leaking

Puddles around your boiler spell danger. This means that the internal parts could be faulty or it’s actually beginning to fall apart. Don’t hang about, get an engineer out quickly, as it could be time for a new boiler.  

Sign 4: Your boiler is making dodgy noises

Growling, whirring or banging noises beyond the boiler’s normal firing-up sound or gentle purr could mean trouble. It could mean many things, from a broken valve and heat pump issues, to general wear and tear.

Instead of spending hundreds of pounds on repairs trying to keep your old boiler alive, it might be time for a boiler upgrade instead.

Where should I get a new boiler?

You can get an A- rated, award-winning boiler from CORGI HomeHeat. 

Want to know more? Visit MyOVO for all offers from CORGI HomeHeat (part of the OVO family). 


1Conditions, exclusions and cancellation charges apply. 

2These are estimated figures based on installing a new A-rated condensing boiler with a programmer, room thermostat and thermostatic radiator controls (TRVs) in a gas-heated home from an older boiler with a programmer and room thermostat. Savings will vary depending on the size and thermal performance of your home. Figures are based on fuel prices as of March 2019. Source; Energy saving trust.

OVO Energy Ltd is registered in England and Wales company number 06890795. Registered office at 1 Rivergate, Temple Quay, Bristol, BS1 6ED.

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