April 2024 -
Written by Jo Alsop
Make the most of your gas boiler

Get honest advice on your boiler and save money today

You paid a lot for your boiler when it was fitted and you will get the most value from it the longer it lasts. In this guide explain why maintaining your existing boiler is more sustainable and up to 55% cheaper than replacement and give you TOP TIPs for keeping your boiler going until a heat pump makes sense for you.


  1. Let your boiler run its full lifespan
  2. Check parts availability for yourself
  3. Get prepared for adhoc repairs
  4. Don't be seduced by a new boiler warranty
  5. Keep the boiler running smoothly and save
  6. Get ready for the future of home heating

1) Let your boiler run its full lifespan

The one of the biggest household savings you can make in any year is not replacing your boiler, at a typical cost of £2.5k-£3.5k.

Contrary to the information found on most boiler manufacturers’ websites, modern boilers have a 22 year lifespan. Yet the big five manufacturers, including Worcester and Ideal, all give 10-15 year lifespans.

This misleading prediction has spread to every corner of the domestic gas industry and is now widely accepted as true. Yet the same boiler manufacturers give lifespans of 15-20 years elsewhere in the world where households expect their boilers to last much longer.

To make matters worse, many customers coming through our business report being advised to replace their boiler sooner than 10 years. They have been told their boiler ‘is approaching the end of its life’ as early as 7 years old, creating a risk that a household may fit three boilers over the course of a 22 year period.

It is unsurprising that a whooping 75% of homes have a boiler that is 12-years old or less. The good news is that 75% of homes don’t need to change their boiler before moving to a heat pump in the next decade (more on the Future of home heating below).

Take action - find out how old your boiler is:

  • Find the boiler’s 7-digit GC number and Google it. This will usually take you to the boiler manual which will give you a rough date. The GC number will be located on the boiler’s data-plate which will be on the boiler - eg on the top (Baxi), in the pull down flap (Worcester) or underneath (Vaillant)
  • If you can find the boiler’s serial number (also located on the boiler), you can ring the manufacturer and ask them to tell you the age.
  • At a very basic level, if the boiler has a white plastic pipe underneath it will be a condensing boiler and less than 20 years old.

2) Check parts availability for yourself

Many of our customers are nudged towards a new boiler at the annual service visit, alarmingly when the boiler is working, when they’re told ‘the parts are getting scarce’.

Boilers up to 22 years old have good parts availability and even older boilers have the core parts available to keep them going.

Take action - know if parts are available for your boiler model in advance:

  • You can check your boiler’s parts availability by Googling the 7-digit GC number again and the term ‘boiler parts’.
  • Don’t be put off that some minor parts are ‘obsolete’. This is common. The main parts gas valve, fan and PCB - will be available. NB sometimes they have updated the original part with a newer version of the same part.
  • Ebay is a great source of parts for older boilers and local breakdown engineers will often fit them for a labour-only cost. Be sure to use Paypal for buyer’s protection.

3) Get prepared for adhoc repairs

If your boiler has good parts availability and you’re comfortable to deal with boiler repairs as they arise, then it is a good idea to find a boiler breakdown engineer to call on. It’s a relationship you can start by booking them for the annual service.

Word of warning, gas engineers that fit boilers have a different skill set to gas engineers that repair boilers. Calling out the right person might be the difference between getting it repaired and being wrongly advised to fit a new boiler.

Take Action - find a good breakdown engineer ahead of time:

  • Gas engineers that repair boilers will usually advertise themselves as breakdown engineers, boiler repair engineers or even diagnostic engineers.
  • Look for genuinely local engineers. If you Google ‘boiler repair’ and your location, the top four listings will always be adverts. Sales companies are clever at reflecting your search term and even your location in their adverts, but they are not local tradespeople and will add a fee to a call out.
  • You should look on the Google map for local business listings and check their websites to make sure they are completely invested in repairing boilers and not replacing them.
  • Alternatively you can check with the boiler manufacturer if your boiler would be covered by one of their fixed price repairs in the event of a breakdown.

4) Don’t be seduced by a new boiler warranty

10-12 year warranties on boilers have played their part in distorting our understanding of lifespan. Many people think that because the warranty has come to an end they should get a new boiler, but even with an extended warranty a new boiler is up to 55% more expensive.

A boiler warranty means the manufacturer will repair the boiler free of charge if it breaks down. However a warranty is not cost-free, as the boiler must be serviced annually to validate the warranty. The 10-year cost of a new boiler, including an annual service and installation cost, is £3,100 - £4,250. The 10-year cost of a maintenance contract on an existing boiler, which will include an annual service, is £2,005.

Take Action - consider a boiler maintenance contract

  • Many mainstream boiler maintenance providers don’t have an age limit to the boilers they are willing to take on contract. Shop around for one that covers your boiler.
  • Boiler maintenance contract costs vary depending on what is included. You need to opt for a full boiler repair package and perhaps hot water cylinder cover if you have one, but radiators and TRVs cover is less valuable.
  • Don’t be afraid of a small excess to lower annual costs. Boiler breakdowns are reasonably infrequent and the odd £50 excess here and there might save you in the long run.

5) Keep the boiler running smoothly and save

Studies have shown that nearly all A-rated boilers are B-E Rated in the home, increasing heating bills by up to 15%. Sadly building regulations have not mandated higher installation standards to overcome the performance shortfall, which means a new boiler fitted today won’t save you any money.

On the rare occasion a new boiler is optimised, the average household will save no more than £120 per annum. With typical installation costs ranging between £2.5-£3.5k it will take 21- 29 years to recoup the upfront cost.

For a fraction of the price you can make your existing boiler more efficient and help it run more smoothly. Many existing boilers are compatible with load and weather compensation controls (the best type of control), but product compatibility is a minefield and you need to find the right control for your boiler. We give you some guidance below depending on what type of boiler you have:

If you have a condensing boiler: if you have a white plastic pipe under the boiler it is a condensing model. Condensing means it can operate more efficiently by recycling its waste heat, but this can only happen when the boiler is set to supply a lower temperature to the radiators. Most homes are fine with a slightly lower temperature.

If you have a condensing combi boiler: if you have a condensing combi boiler you can turn down the flow temperature on the front of the boiler and save today. Turning the dial with the radiator icon to the 12 o'clock position will work for most households. A study found that households can save around 9% on their gas bill with this quick fix. The correct load or weather compensation control will adjust the flow temperature automatically and bring a load of other efficiencies to the system. You will need to get your GC number again and give the boiler manufacturer a ring to find out which load or weather compensation controls are compatible. As a quick guide: Worcester and Vaillant boilers only work with Worcester and Vaillant’s own compensation controls. For other boilers, you need to find out if they can run on the OpenTherm language and fit an OpenTherm compatible control.

If you have a condensing boiler that works with a cylinder: unlike combi boilers, there is no quick fix for reducing the flow temperature if you have a cylinder. Boilers that work with cylinders are set up to provide a single temperature for heating and hot water, therefore if you turn down the heating dial on the boiler you will make the hot water cylinder too cool. Many boilers with cylinders will also work with load and weather compensation controls, but most need other changes to the system to make it all work. You will need to get your GC number again and give the boiler manufacturer a ring to find out which load or weather compensation controls are compatible.

If you have a non-condensing boiler: your ‘next best’ action is to fit a smart control, but word of warning - smart controls don’t work well with heat pumps. If you plan to keep the boiler going for a couple of years until you fit a heat pump, we recommend sticking with the existing heating control.

6) Get ready for the future of home heating

Gas boilers are the biggest source of CO2 from our homes. Replacing your boiler with a heat pump is the single biggest thing you can do to cut your carbon footprint, even if your boiler is just a few years old.

If you’re not ready to fit a heat pump then the most sustainable thing you can do is keep the gas boiler going until you are. Replacing your boiler early will lock you into gas for longer, as you will be reluctant to pay out for a heat pump in the five years that follow.

What is a heat pump?

Heat pumps are a type of renewable heating that everyone will switch to eventually. Heat pumps cut your energy demand by 65-75% and run on clean electricity. 80% of homes will move to a heat pump in the coming decade and the rest will run on heat networks whereby a large clean energy source powers multiple homes.

What is a hydrogen boiler?

Hydrogen boilers don’t exist, likewise hydrogen-ready boilers and likewise green hydrogen in sufficient quantities to power anything.

It may be that hydrogen is mixed into our gas supplies to make a hydrogen-blend, but all existing boilers are hydrogen-blend ready. Should green-hydrogen become viable it will be needed for transport and industry.

To date, 56 independent studies found no role for hydrogen in home heating, including the National Infrastructure Commission. Homes will all move to heat pumps over the coming decades.

Are you ready to fit a heat pump? Find out in our comprehensive guide: 2024 is the year of the heat pump

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