Don't let your new boiler burn your cash

If you think a new boiler will save you £350 per year or your existing boiler is 7 years old, please read on. The truth is you might be replacing your boiler unnecessarily and for all the wrong reasons. The UK has the biggest boiler replacement market in Europe and not just because of population size. Rather we fit new boilers too frequently either through poor advice and/or premature aging due to incorrect installation. In this blog, I explore the necessity for boiler replacement and how to achieve true energy savings and longer lifespans when you do.

1. Do you definitely need a new boiler?
2. The efficiency/fuel saving argument for a new boiler
3. How do we get closer to higher efficiencies in the home?
4. How do we avoid premature replacement of our boilers?

1) Do you definitely need a new boiler?

Boilers should last 22 years, but sections of the domestic heating industry have put an expectation of 10-15 years on the lifespan of a boiler and replacements are regularly recommended at 7 years.

My first house did not have heating and we fitted a brand new radiator system with a Worcester Bosch 24i Junior combi boiler. That was in 2004 and it was still going strong 16 years later when I sold the house, with only one part replaced over its lifetime. It was a good little boiler of course, but it was also set up on a clean, properly designed system.

Whether my old boiler makes it to 20 years depends largely on if it breaks down again. Parts are still available and affordable, but will the new owner be advised to fit a new boiler because it is past its perceived life expectancy of 7-10 years?

The risk of an unnecessary replacement depends entirely on who attends. If a boiler breakdown specialist attends then they will gleefully repaired it; that is their job. If however a boiler installer attends, then they may advise replacement.

My advice

So my first piece of advice is, make sure you really need a new boiler and call out the right person to attend a breakdown. If it is 7-10 years old, it should last the same again – assuming it has been set up correctly. Poor system design is a big factor and is considered more below.

2) The efficiency/fuel saving argument for a new boiler

If you are being advised to replace your boiler to something more efficient, the chances are you will only save around £40 on average per annum.

We are too often advised to upgrade from an old boiler to a new boiler on the basis it will save us hundreds of pounds per year in energy bills. This is a compelling reason, particularly if we need to be persuaded to change our boiler for little reason other than it is past is perceived lifespan of 7-10 years.

Energy Performance Certificates (EPCs), which are mandatory with every house sale and rental, will also recommend upgrading from a ‘non-condensing’ boiler to a ‘condensing’ boiler in order to improve the energy banding of our homes.

The example is often given that upgrading from a G rated boiler (about 60% efficient) to a new A-rated condensing boiler (92% efficient) will save around £350 for the average home. But this is an extreme example. High efficiency condensing boilers have been mandatory for 15 years and even non-condensing boilers – like my little Worcester 24i Junior – manufactured in the years up to the legislation changes were around 78% efficient. The chances are you are swapping out a reasonably efficient boiler.

An Energy Saving Trust field study of 30 A-rated condensing combi boilers and 10 A-rated heat only boilers found them to average 83% and 80% efficient respectively 'in the home', a great deal lower than 92%. In the example of my Worcester 24i junior combi boiler, my efficiency improvement would likely be from 78% to 83%, which represents an energy saving of around £50 per annum.

My advice

For those that have a boiler that is at end of its useful life, the payback on your new boiler sounds depressingly low. But do not lose heart, new boilers do have the potential to be 92% efficient, or higher, but they need to be set up correctly. My advice is to read section 3 below.

3) How do we get closer to factory-rated efficiencies in the home?

Your new boiler will only come close to its factory rated efficiencies if it is correctly sized and correctly set up with a compatible advanced heating control - as a minimum.

If you need a new boiler, then it should at least have a chance of achieving its factory rated efficiencies. Modern boilers are what are known as ‘modulating’. Modulating means they can adjust their output up and down to meet lower heating demands and therefore operate efficiently all year around.

The truth is that a modulating boiler needs a modulating control to work at its most efficient, but they are not mandatory. Just to confuse matters further, smart controls are not necessarily modulating controls even though they are compliant with minimum efficiency standards for new boilers.

Modulating controls must speak the same language as the boiler. Some manufacturers do not allow third party heating controls to work with their boilers because they keep the language of their boiler private. Third party controls will still operate the boiler, but they will not modulate the boiler, only switch it on and off.

My advice

If in doubt, pick the boiler manufacturer’s own modulating control, although functionality will be limited (for example no extra home security features such as the Nest) or go with a boiler and control that both use the ‘Opentherm’ language.

4) How do we avoid premature replacement of our boilers?

The correct set up and a clean system are vital components to a long and healthy boiler life. Whilst new boilers come with A-rated labels and 92% efficiency potential, it really is just potential and reaching it depends entirely on getting the whole system right.

When I say the whole system must be right, I do not mean removing all radiators and pipework. Rather getting the controls right and the system clean and balanced. This can be done with or without the catalyst of a new boiler and at no extra cost to a new boiler installation; just a bit of installer know-how.

The importance of a clean system cannot be underestimated, but clean does not mean filling it with chemicals. Chemicals have their place, but heating systems are set up to run on clean, deionised, water.

Corrosion and the resulting ‘sludge’ in the system is often cited as a reason to use chemicals and they can certainly be used to try to breakdown a build up of a sludge; along with a flush of some kind. Corrosion can be entirely avoided however by fitting a device that can remove air in the system. It is air that causes corrosion, not water interacting with metal, and it is always better to prevent corrosion than treat the symptoms of it indefinitely.

My advice

We have lots of other guides on the website to help you find a great boiler with a compatible heating control. Try the two below as a starter.