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Boiler setting changes that could save you 8% on your gas bill

The headlines

This is one of the biggest, simplest, most immediate and easiest ways to save gas without losing any comfort: Reducing the temperature of the water flowing through your radiators.

This is NOT about lowering the wall thermostat in the house, or the settings on your radiator valves.

This is mainly for homes with a combi boiler (where you have a boiler but no water tank) .

In many cases you can make the changes yourself. You can save up to around 8% on your gas bill, a saving of around £80-100 on the typical annual bill.

If you have a boiler system that uses a water tank you need to take professional advice on how to make these savings. Minor changes to your system are often needed for safety reasons.

This article provides a very brief summary of this subject. It also points you to a number of excellent web pages that will:

  • Tell you if your boiler is the type that can be adjusted

  • Give you practical step by step guides for common boilers

The goal is reduce the temperature of the water flowing round your radiators as much as you can while still feeling your home gets warm enough.



Since 2005 any new boiler installed has to be a condensing boiler. These are meant to be more efficient than the generation of boilers before 2005. But sadly, the majority in the UK are not set up correctly and are not operating anywhere near as efficiently as they should.

Boilers are really unhelpful. They spend an awful lot of money on our behalf, but don't provide ANY information on whether they setup right and are doing their job efficiently.

Some of the latest ones give you lots of information. For the vast majority of the 28 million boilers in the country though, they tell you diddly squat.

Not only that, there are many that have the most unhelpful controls like this one below. A boiler like this gives you no clue at all what to do other than provide a graphic on the front that indicates 'turn me'.

Not terribly helpful

Even if you have had your boiler serviced regularly it doesn't mean it is set up to work in the most efficient way for your situation.

I talk with experience as having visited 30 homes last February looking at their home energy efficiency. Only two of them had boilers that were set up to operate efficiently.

Next time you have your boiler serviced, grill them on this subject!


Checking you have the right type of boiler

First, confirm you have a condensing combi boiler

If you have no hot water tank, it means you have a COMBI boiler.

Now you just need to confirm that it is a CONDENSING combi boiler,.

If there is white plastic pipe of around an inch in diameter going off to a drain somewhere, then your boiler IS a condensing type.

If your boiler doesn't have this plastic pipe, then it isn't a condensing type, and this article isn't relevant to you.


How to make the adjustments yourself

This very short video gives a super overview of what you need to do. Basically, the goal is to reduce the temperature as low as you can while still feeling warm enough.

Many boilers have crude controls like the photo above. Some, like the ones in the video hear have electronic displays and push button controls.

If you are unsure how to make adjustments on the more modern types, owners manuals for all central heating boilers are very easy to find just by Googling.

It sometimes takes a little experimentation over time to get the right setting for different weather conditions.

How the system is designed will have an effect on how much savings can be made.

If the boiler is oversized for example, or if the radiators are on the small size for the needs of a home, then the benefit will be lower.

But, if your system is one where you can at least try, try.

Running the boiler and radiator temperatures lower than you did in the past might mean the heating needs to be put on a little earlier to get a home warm. It might seem counter-intuitive, but it will definitely bring savings if you can do it.

Reducing radiator temperatures also makes everything in your heating system last longer, including the boiler itself.


Tips on adjusting for different weather conditions

The colder it is outside, the hotter your boiler will need to run to keep your home warm.

In milder weather you can run the boiler at lower temperatures and make it more efficient.

If you only have simple boiler controls like the picture below you, could write on the front the positions that suit different weather.

This makes it easy to tweak the boiler to the most efficient setting, and give you confidence the boiler is operating as efficiently as it can.

Modern boilers have the facility to do all this stuff automatically. It doesn't mean if you have a very new boiler that it does this though. It will depend on what the boiler installer did. The feature is called "weather compensation".


Hot water temperature adjustment

Combi boilers also always give you a way to adjust the temperature of the water going to your hot taps. This is often adjusted using a simple dial similar to the one in the photo above.

For the water, the hottest most people want it is for washing up in the sink, so adjust it down until it is hot enough for sink washing.


Other information sources

Below are some links to web sites with more detailed information and some with very practical information to help you step by step.

Which magazine article here gives a good overview of this subject.

This Heating Hub web page provides excellent information on how to work out IF you can do this for yourself and a guide as to how to do it. This includes a video tutorial.

A different approach here, with an interactive step by step guide.

This recent article in the Sun newspaper is real example of what can be achieved. This article is very credible as Tim featured in the article is a friend of mine and he really knows his stuff.

A further real world example featured in the Sun newspaper here.

For the real geeks, this is a really techy web page from Heat Geek who really know there stuff, going into the physics behind it.


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I run this website as a hobby, because I care about this stuff, and do it for no commercial purpose. If you have valued what you've seen, please tell other people about it.

If you have any other suggestions for additions or changes to site content do please let me know. While I have made every effort to ensure that the information contained on this website is correct, I cannot take responsibility for errors or omissions.

All content on the site should be treated as information and not advice. You should take professional advice where appropriate to different site articles.


Mark Thompson

Get Energy Savvy - simple practical home energy efficiency information

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