Do you, like many others, want to swap out your old, gas guzzling regular or system boiler to a new, modern efficient combi? Find out what's involved and how much it may cost.
- Why change to a combi boiler?
- What is a combi boiler?
- Benefits of combi boilers
- What is involved in changing to a combi boiler?
- How long does changing to a combi take?
- How much does converting to a combi boiler cost?
- How much does it cost to convert from a system/regular boiler to a combi boiler? £2,500 → £4,500
- New boiler conversion costs:
- How much does a back boiler to combi conversion cost? £3,000 → £5,000
- Want to change your boiler to a combi?
Are you thinking about replacing your conventional boiler with a combi boiler? Does it keep you up at night? Is your wife getting jealous because you keep looking at new fancy boilers?
Changing from a different type of boiler to a new one can be a trip into the unknown.
This is even truer if you've never had a combi boiler in your home before, and you are converting from an ancient back boiler, heat only or a system boiler - or an open fire in the middle of your living room.
Many people would much rather remain with what they are used to, but in some cases changing to a combi boiler can make a lot of sense. Chances are you’re not using a rotary phone anymore, either.
However, with that said, it's important to consider whether a combi boiler is appropriate for your property, this is especially true for larger properties with a high demand for hot water.
Combi boilers do both your heating, and your hot water, from a single unit. They're the heating dream humanity has longed for.
Typically, the cost of a boiler conversion will be more than a standard like-for-like replacement since it usually entails more time and labour. You can’t simply switch the same boiler like Indiana Jones exchanging a golden idol for a bag of sand.
So what else do you need to know? In this guide, we'll answer the most common questions for those considering changing to a combi, including costs, common scenarios and whether it's worth it or not.
PS we fit new combi boilers with gas installation nationwide. Simply answer these questions, get your fixed price and you could get it installed as quick as tomorrow
Why change to a combi boiler?
One of the major reasons for converting from an older type of boiler to a modern combi boiler is the improved energy efficiency. It’s like giving your boiler the body of a twenty-year-old in the prime of his life you’d want for yourself.
Since combi boilers heat the cold water directly from the mains and do not need to keep a constant store of hot water. They are typically much more energy-efficient, helping you to reduce energy waste and save money on your bills.
Another major reason is that they are smaller and have fewer components than system and heat-only boilers, this not only makes servicing and maintenance easier and cheaper, but it also helps to save space and limit unsightliness in your home. But then there’s still your mother-in-law’s self-made painting to contend with…
The good news is that even if your property has a high demand for hot water e.g. you have multiple bathrooms, you can still benefit from a hybrid combi called a storage combi boiler, which comes with its own internal water storage tank. It’s like a grandma who keeps digging candy out of her purse when you surely thought all the food was gone.
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What is a combi boiler?
"Combi" is short for combination boiler and is named as such since it provides both hot water and heating from a single unit, typically wall-hung, like a hideous modernist piece of art.
This is an advantage over older home heating systems that were typically composed of an immersion heater, fed with water from a header tank in the attic.
The immersion heater needed to be turned on well in advance of requiring hot water, this meant that water wasn’t in demand and since they are extremely inefficient, they cost a considerable amount of money to operate. It’s like hiring those fan-waving servants you see in movies rather than an electric fan.
It is also a big advantage over the system and heat-only boilers that need to constantly keep storage of hot water, which can cost significantly more in comparison to a combi boiler.
They are also much larger, made up of multiple components, and so require much more space to install. For this reason, they were often also considered much more unsightly. Or at least harder to hide, much like Aunt Trudy.
Curious to know which boiler brand performed worst? Find out in our report on the worst boilers.
Benefits of combi boilers
What are the major benefits of combi boilers when compared to other types like system and heat-only boilers?
#1 They are extremely efficient
If you are looking for a boiler that's highly energy efficient, a combi (combination) boiler is the perfect solution. In fact, they’re so efficient, if they could do your job, you’d lose it in weeks.
They can be used to heat the home as well as its water, saving you a huge amount of heating bills. In fact, according to Energy Saving Trust:
By trading your old boiler in for a modern boiler, you could save around £340 and a whopping 1,500kg of carbon emissions a year.
#2 Combi boilers have a compact size
Their compact size makes them ideal for even the smallest of properties, and since they use the mains as the water source, you will not have to make space for a cumbersome water tank or cylinder. In some parts of London, that’s half a bedroom.
In fact, some of the smallest combi boilers are so compact they are marketed and sold as “cupboard-fit” combi boilers.
#3 Hot water on-demand
Another plus is that because they can instantly heat the water you need; you will not have to worry about having enough water in the hot water storage tank, or it's running out. It’s even faster than modern online groceries.
#4 Installation location more flexible
Since a combi is relatively small, and it is a single unit, there is typically more flexibility as to where you can have it installed within your home. Notice it only said ‘more flexibility’, so you can’t double your boiler as a chandelier (yet).
This isn’t always the case with systems and regular boilers that require a storage tank and/or overhead tank, which can severely limit the options.
What is involved in changing to a combi boiler?
Once you have decided to take the plunge and get your conventional boiler converted to a combi, then it's a good idea to learn about the overall process, so you can appreciate the time, costs and labour involved.
Changing to a combi boiler – the process explained:
Once you have booked your boiler conversion, the Gas Safe engineer will arrive at your property and carry out the following:
Drain the existing central heating system, including boiler and radiators.
Remove the existing/old boiler.
Remove cylinders and header tank (in the attic).
Upgrade the gas pipework to 22 mm.
Install the new combi boiler.
Carry out a chemical/power flush on the heating system.
Install a smart thermostat e.g. Nest or Hive.
Configure the smart thermostat to work with the new boiler.
Register the warranty.
Carry out safety checks.
Provide the relevant building regulation certification.
Provide a brief overview of the new system and how to use it to the homeowner.
They may or may not take coffee while working.
How long does changing to a combi take?
As you may be able to appreciate, carrying out a boiler conversion rather than a straightforward combi swap does take a little longer than a regular boiler install.
On average, it will take 2 days to complete, but this can vary depending on the complexity of the job.
This is compared to just 1 day that it takes to carry out a straightforward like-for-like replacement for illustration - still a lot slower than Indiana Jones.
How much does converting to a combi boiler cost?
How much does it cost to convert from a system/regular boiler to a combi boiler? £2,500 → £4,500
Upgrading a traditional boiler to a combi boiler is a bucket list regular for most UK homeowners, sitting seven places above seeing the Pyramids and just one below breaking free from lifelong, crippling debt.
Conversions can be complex beasts, and they come with costs you'd associate with a complex beast.
Please note: Ultimately an accurate boiler installation cost depends on a variety of factors personal to your situation.
But exactly how much extra will you be paying?
Included in the cost of a boiler conversion, is the full removal of your old boiler & water cylinder, newly upgraded pipework fed to the existing or new location of the incoming combi boiler and of course, the new combi boiler itself.
...and that’s a simplified version.
It can be a big job, requiring two days of work and engineers so, in tune with their tools, they can make a crowbar dance.
Putting you out of your misery early, you’ll roughly be looking at at additional £800 - £1200 worth of expense on top the standard boiler swap cost.
New boiler conversion costs:
These fixed prices assume a straightforward conversion and the costs include all of the above, plus upgraded heating controls, a full chemical cleanse of your existing boiler system, boiler filter and registration.
Do note that other, much more expensive quotes are available elsewhere. Try your energy provider if you fancy a laugh.
Boiler Model | Guide Cost |
|
Ideal Logic 24kW | From £2,790 | |
Ideal Logic 30kW | From £2,990 | |
Viessmann Vitodens 050-W 29kW | From £3,039 | |
Viessmann Vitodens 100-W 26kW | From £3,370 |
When converting your regular boiler into a combi boiler, do remember that any boiler manufacturer can be fitted so long as it’s the correct size and powerful enough for your hot water demands consider referring to our best combi boiler guide to gain more insight than you ever thought possible.
Want to know which boiler power is right for your home? Check out our "what size boiler do I need" guide.
How much does a back boiler to combi conversion cost? £3,000 → £5,000
You can scan over a more comprehensive back boiler description in this article if you’ve run out of paint to watch dry…
…But a broken back-boiler is an old dog that needs to be put down, or ‘sent to the farm’, if you’re feeling too sentimental about your back.
They can no longer be repaired in accordance with modern regulations and you will need to convert your system - most likely to a modern combi boiler.
Heatable applies a transparent, and fixed cost of £395.00 on top of our standard conversion costs. This can get much steeper when buying from other national companies so make sure you don’t settle for your first quote.
The work involved in the conversion of a back-boiler is very much similar to a standard conversion in that it includes the removal of your entire existing system and introduction of the new combi and required pipework, however, it’s the awkward location of the back boiler behind your fireplace that incurs the sometimes significant extra cost.
Many installers and installation companies hate carrying out this work and will therefore simply price themselves so high they can just about bear it or high enough to discourage customers.
Related reading:
Want to change your boiler to a combi?
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