This is the first in a new series of content where we will give you advice on how to make your home more energy efficient. We will focus on actions that you can take today to help you save money and reduce your carbon footprint. First up, gas boilers:


1. Quick safety check

If your boiler does not turn on when you expect, is leaking water or making a strange sound (such as a banging or buzzing noise) then please contact a GasSafe engineer. If you can smell gas please click here for safety instructions on what to do.

All of our tips here should work for most gas boilers, but you should always check and follow the manufacturer’s instructions for your particular boiler.

If in doubt, call a GasSafe engineer to help you.


2. High Boiler Pressure can lead to a drop in efficiency and shorten its life

With a typical ‘wet heating system’ your boiler heats up water to warm your radiators and needs a minimum pressure to pump the water around your system, ideally between 1 to 2 bar. However, it’s normal for your pressure to go up to 2.5 bar when you’re heating, and hot water are being used.

To lower the pressure to stay within the recommended range the simplest step is to bleed one of your radiators to remove excess water. If you find that your boiler pressure continues to increase, check that the filling valve under your boiler is closed. If in doubt, contact a GasSafe heating engineer.

Check your pressure dial regularly, usually positioned on the front of your boiler.

Picture: check your pressure dial regularly, usually positioned on the front of your boiler.


3. Low boiler pressure could prevent the boiler turning on

Boilers require a minimum amount of pressure to work. If water pressure drops below 1 bar there are steps you can take to re-pressurise your boiler by adding water to the system using its filling loop:

  1. Check your boiler’s manual before you begin

  2. Turn your boiler off and allow everything to cool down

  3. Find the filling loop

  4. Make sure you can see your boiler pressure gauge before attempting to re-pressurise

  5. Open the first valve fully

  6. Open the second valve slowly to start adding water to your system

  7. Once the pressure reaches 1.5 bar close both valves and lock

  8. Turn your boiler back on. You may need to press the reset button

Example of a gas boiler filling loop

Picture: an example filling loop - note the two black valves shown are in the closed position.

If your pressure continues to drop or you are unsure about how to re-pressurise your system, we strongly recommend you contact a GasSafe heating engineer.


4. The correct flow temperature

The latest boilers control the temperature of the water that flows around your heating system which can help reduce both heating costs and carbon footprint.

As always, please check your boiler’s manual before proceeding.

Example gas boiler control panel

Picture: optimal flow temperature depends on your system and can be adjusted on the control panel. In this example the dial with the radiator icon allows you to control the flow temperature.


Condensing boilers

Condensing boilers are the most efficient type of gas boiler because they reclaim heat that would otherwise be lost out of the flue. In general, it is better to heat your home up slowly with a condensing boiler using a lower water temperature, between 60°C and 70°C, to work more efficiently. If the water temperature is set any higher the boiler is unable to efficiently cool & condense which can lead to higher energy bills. By changing your settings to the correct water temperature you could save up to 15% on your heating bills.

TIP: If you're not sure what type of boiler you have, typically a condensing boiler has a white plastic pipe coming out the bottom. Check your boiler's manual, or you can try searching for the make and model of your boiler online here.

TIP: If you're not sure if your boiler is condensing properly take a look at the gas that exits the flue outside your home. If you continue to see white plumes whilst your heating is on and is running it’s usually a sign that the heat is being lost to the outside. Please note, it is normal for this to happen when your boiler initially turns on.


Non-condensing boilers

Non-condensing boilers are up to 15% less effective converting gas to useful heat. By switching to a condensing boiler, you can immediately benefit from a more efficient system resulting in meaningful energy savings.


Underfloor heating

The ideal temperature for your system will depend on your setup, and the type of floor you have. General guidance: if the system operates with thermostatic mixing valves, use 45°C temperature for cement / screeded floors and 55°C for timber suspended and floating floors.

As always, if you are unsure, or we've just got way too technical, contact a GasSafe engineer or talk to one of our team about whether an air source heat pump could be a good fit for your home.

To save on energy consumption you may find using an air source heat pump could be a good fit for your home. Our team of heating experts are available to answer any questions you may have about the benefits and how they work. Learn more about air source heat pumps here.