Skip to the content
Trustpilot logo 0800 61 22 302

How to use your combi boiler efficiently

If you’re not using your combi boiler efficiently, you could be missing out on significant savings to your energy bills.

While combi boilers are designed to work efficiently, the way you use them can have a huge impact on your carbon footprint and how much you pay for your heating. Here, we tell you how to get the best out of your unit.

How does a combi boiler work?

The word ‘combi’ is short for ‘combination’ which means it has two functions – heating and hot water.

Heating your home involves hot water being sent to your home’s radiators via the boiler’s primary heat exchanger and then recycled back. 

Hot water is sent to your taps, showers and other outlets via the secondary plate heat exchanger and kicks in the moment you turn the outlet on. Water is taken from the mains, is heated by the boiler, and sent to the outlet.

How efficient are combi boilers?

Unlike other types of boiler, a combi boiler only heats water when it’s needed, which reduces waste. These efficiencies make combis ideal for smaller homes with 1-3 bedrooms. Households that use a lot of water or have a high number of radiators, will likely benefit from a regular or system boiler.

Condensing combi boilers are more efficient than previous non-condensing models, as they use the heat created by combustion in addition to the resulting water vapour. This way, little energy is wasted.

Today’s combi boilers have been designed to be efficient, both in terms of output and running costs. In fact, here at Boiler Plan we only install units with an efficiency rating of 90%. This means that only 10%, or 10p, of every £1 spent on heating your home is wasted. This is in contrast to older non-condensing boilers, which have a rating between 60-70%.

How to use combi boilers efficiently

There are a number of ways to improve the efficiency of your combi boiler, some of which are easy to do yourself.

Turn the temperature down 

The easiest way to increase energy efficiency is to set your thermostat to a lower temperature. Research by the Energy Saving Trust suggests that turning down your thermostat by one degree could result in savings of £80 each year and 320 kg of carbon dioxide, which is the same as a return flight from London to Paris.

You can lower the temperature through your thermostat or by adjusting the individual radiators through their built-in valves. These won’t control the boiler but will reduce the flow of water in each radiator.


Purchase water-saving taps and showerheads

To limit the amount of water you’re using, you can opt for water-saving taps and showerheads, both of which limit the amount of water that can flow through them. This will mean that your boiler doesn’t have to heat as much water.


Check for leaks 

Leaking pipes and taps can lead to significant levels of wasted water over time, reducing the efficiency of your heating system. If you’re not able to remedy the problem yourself, you should contact a qualified plumber.


Fit thermostatic radiator valves

While manual radiator valves work perfectly well, thermostatic radiator valves, or TRVs, give you the ability to set the exact temperature you’d like the room to reach. Once the TRV senses that this temperature is reached, it stops the flow of water into the radiator, reducing the amount of energy used.

Upgrade to a smart thermostat

Upgrading to a smart thermostat could be the key to improving efficiency. These can be controlled via your mobile phone and can be programmed to turn your heating on and off remotely. This can be particularly useful when you find yourself away from the house unexpectedly with the heating programmed to come on.

For even greater control, some smart thermostats allow you to set the temperature for individual rooms. For example, if you don’t need the heating on in the kitchen but want the living room to be nice and cosy, you can set individual temperatures with the thermostat. This will also help reduce your energy consumption.


Make sure your home is properly insulated

If your property doesn’t have adequate insulation, then your boiler will have to work overtime to keep you warm. Double glazing, draft proofing, cavity wall insulation and loft insulation are some of the ways that you can keep your home warm and give your boiler a break. 

Get an annual service

The best way to ensure that your central heating system is working correctly is to have an annual boiler service by a Gas Safe registered engineer. This will uncover any issues or faults that are contributing to your unit not running as efficiently as it should be.