Boilers
Combi Boiler Swap in Liverpool: Same Position, Fixed Price, No Guesswork
A straightforward like-for-like boiler swap, checked properly first so 'straightforward' actually turns out to be true, priced in writing before anything is disconnected.
Gas Safe registered no. 576059 · new boilers fully fitted from £1,299
Gas Safe registered
Registration no. 576059 · licence no. 3715984
Fixed written prices
Agreed before work starts, no hourly rates
Boilers from £1,299
Fully fitted, immediate installation available
FREE Gas Safety Certificate
With every new boiler installation
Open 7 days
Mon–Sun, 8:30am–5:30pm
Overview
What This Service Is, and Who It Is For
What it is
A boiler swap replaces an old combi boiler with a new one in the same location, reusing the existing gas, water and flue routes wherever they are still fit for purpose. It is quicker and usually cheaper than a full installation because the pipework layout is already there, but 'swap' does not mean 'identical box, no checks'. We verify the gas supply is correctly sized for the new boiler's higher efficiency, check the flue meets current clearance and terminal position rules even though the old one may predate them, and cleanse the system so a new heat exchanger is not fed sludge from twelve-year-old pipework.
Who it is for
Homeowners with a combi boiler that has reached the end of its life, is becoming unreliable, or is simply old enough that parts are getting harder to source, and who are happy with the existing system layout, the current boiler position and roughly the same hot water performance. It is generally not the right job if you want to change from combi to system boiler, move the boiler to a different room, or if the property has never had a proper heat loss assessment done.
When you need it
As soon as an ageing boiler starts showing repeated faults, becomes uneconomical to keep repairing, or fails outright. Swaps can often be turned around quickly because there is no redesign involved, which matters if you currently have no heating or hot water.
Why it needs a registered engineer
Even a like-for-like swap is notifiable gas work, and the parts of a swap that go wrong are almost always the parts someone assumed did not need checking: an undersized gas pipe that worked for an old, less efficient boiler but chokes a new one, a flue terminal position that was compliant twenty years ago but is not now, or an old system so full of sludge that it kills the new boiler's heat exchanger within two years.
The cost of leaving it
What Happens If This Gets Left
A boiler swap looks like the simplest job in heating, which is exactly why the checks that make it safe get skipped by installers in a hurry.
Risks and escalating costs
- Modern condensing combis often need a higher gas flow rate than older non-condensing boilers did. Fitting a new boiler onto an undersized gas pipe means it cannot reach full output, or worse, runs starved of gas intermittently.
- Flue regulations have tightened over the years around distances from windows, doors, boundaries and other flue terminals. An old flue position that was fine when first fitted can be non-compliant for a new installation and simply cannot be reused without alteration.
- Skipping the system cleanse on a swap is one of the most common causes of early failure in an otherwise good new boiler, because sludge that built up around the old unit's more tolerant heat exchanger blocks a new, tighter one within a year or two.
- A 'swap' quoted without a proper visual survey sometimes turns out not to be a straightforward swap at all once the engineer arrives and finds copper pipework too narrow, an inaccessible flue route, or asbestos-containing materials around the old boiler casing.
- Rushing a swap to save a day's labour by reusing old pipework fittings and isolation valves without checking them often means the next minor repair requires draining the whole system, because there was no proper isolation fitted.
Mistakes we are called out to fix
- Assuming any new boiler will simply bolt onto the existing pipe stubs regardless of gas pipe diameter or condensate route.
- Not checking whether the current flue terminal position actually complies with current Building Regulations before booking the work.
- Skipping a system cleanse to save time or cost, then wondering why the new boiler is faulting within eighteen months.
- Choosing a boiler output based on the old one's rating rather than checking it still matches the property's actual hot water and heating demand.
- Not asking whether a magnetic filter is included, since retrofitting one later is more disruptive and costly than fitting it during the swap.
Our process
How We Carry Out the Work, Step by Step
- 1
Step 1: Pre-swap survey
We check the existing boiler position, gas pipe size and route, flue terminal position against current clearance rules, water pressure and flow, and the general condition of the pipework and radiators before confirming the job is a genuine swap.
- 2
Step 2: Fixed price confirmed in writing
You get the boiler model, what is included (filter, cleanse, flue changes if needed, condensate route) and the total price in writing before any work is booked in.
- 3
Step 3: Isolation and removal
Gas and water are isolated, the old boiler is removed, and we check the state of the pipework and any wall damage or fittings that need attention before the new unit goes up.
- 4
Step 4: Installation and any necessary upgrades
The new boiler is fitted, with any gas pipe upsizing, flue relocation for compliance, or condensate pipe improvements carried out as identified at survey, not discovered as a surprise mid-job.
- 5
Step 5: System cleanse, commissioning and handover
The system is flushed and dosed with inhibitor, the boiler is commissioned with combustion readings taken, the Benchmark record is completed, and you receive your Gas Safety Certificate and warranty registration before we leave.
What you get
The Difference It Makes
Quicker than a full redesign
Reusing a sound existing layout means most swaps are completed in a single day, minimising time without hot water and heating.
Checked, not assumed
Gas pipe sizing, flue compliance and system condition are verified before we call it a straightforward swap, so there are no mid-job surprises on price.
System cleansed, not just the box changed
A full cleanse and inhibitor dose protects the new boiler's heat exchanger from whatever has built up in the pipework over the life of the old one.
Fixed written price before work starts
The figure you agree to is the figure on the invoice, including any gas pipe or flue upgrade identified at survey.
New boilers fully fitted from £1,299
A like-for-like swap is often one of the more cost-effective ways to replace an ageing combi, especially where no redesign work is needed.
FREE Gas Safety Certificate included
Every new boiler installation, including a swap, comes with a Gas Safety Certificate for the new appliance at no extra cost.
In detail
What Makes a Boiler Swap Straightforward, and What Doesn't
The single biggest factor in whether a swap stays simple is the gas pipework already installed. Many combi boilers fitted ten to twenty years ago in Merseyside terraces and semis were connected with 15mm gas pipe, which was often adequate for the lower gas rates of older, less efficient boilers. Many modern condensing combis need a higher gas flow to hit full output, and a pipe that is too narrow, too long, or carrying too many bends will starve the new boiler under load, causing it to fail to reach full output or lock out intermittently. We calculate the pipe sizing for the specific new boiler rather than assuming the existing pipe is adequate simply because the old boiler ran on it.
Flue position rules have changed and tightened over the years, covering distances from opening windows, doors, other flues, boundaries and areas where people might walk or gather directly beneath a flue terminal. An old flue that was correctly positioned when the previous boiler was fitted, sometimes twenty-plus years ago, is not automatically compliant for a new installation. Where a flue position no longer meets current rules, we explain the options: rerouting the flue, which is usually the straightforward fix, or in rarer cases repositioning the boiler slightly, which turns a swap into a small installation project rather than a pure swap.
System cleanse is not optional on a genuine swap, whatever the age of the existing pipework. An old boiler with a wider heat exchanger tolerates a certain amount of sludge and debris that a modern condensing boiler's tighter internal passages will not. Skipping the cleanse to save time is one of the most common reasons a brand new boiler starts faulting within its first two years, and it is also a reason manufacturers can refuse a warranty claim, because installation-caused sludge damage is excluded from cover.
Condensate disposal is worth checking properly rather than assuming the old route still works. Condensing boilers produce an acidic condensate that needs to run to an internal waste pipe or a suitably insulated external route. Older installations sometimes used external condensate pipes with no insulation at all, which freeze solid in cold snaps and cause the boiler to lock out on the coldest days of the year, exactly when you need it working. A swap is the ideal time to correct that properly rather than leaving a known weak point in place.
Residential and commercial properties
Boiler swaps are common across Merseyside terraces, semis and flats where a combi has been in place for a decade or more. We survey each property individually before confirming it is a genuine like-for-like swap, because the layout that looks identical to the last boiler is not always identical once we check the pipework and flue against current standards.
Variations of this service
Straightforward same-position swap
Existing gas pipe, flue position and system condition all check out, so the new boiler goes into exactly the same location with minimal alteration.
Swap with gas pipe upsizing
Existing 15mm gas pipework upgraded to 22mm where the new boiler's gas rate requires it, sized and quoted at survey stage.
Swap with flue relocation
Where the current flue terminal no longer meets clearance rules, rerouting the flue to a compliant position while keeping the boiler in the same room.
Swap with full system cleanse
Power flushing or chemical cleansing an older system before connecting the new boiler, particularly important on systems that have never been cleansed.
Materials, parts and equipment
- Worcester Bosch, Vaillant, Baxi, Heatline and Main combi boilers
- 22mm and 15mm copper and press-fit gas pipework
- Compliant balanced flue kits and terminal guards
- Insulated internal and external condensate pipework
- Magnetic system filters and central heating inhibitor
- Full-bore isolation valves for future serviceability
Questions
Boiler Swap: Frequently Asked Questions
What is the difference between a boiler swap and a full installation?
A swap replaces the boiler in the same position, reusing existing gas, water and flue routes where they are still fit for purpose. A full installation involves redesigning the system, changing boiler type, or relocating the boiler, and takes longer.
How long does a combi boiler swap take?
Most straightforward swaps are completed in a single day. If a survey identifies gas pipe upsizing or a flue relocation, we tell you in advance and the timescale is adjusted and confirmed in writing.
Will my new boiler fit in exactly the same spot?
Usually, yes, provided the flue terminal position meets current regulations. We check this at survey stage rather than assuming the existing position is still compliant, since flue rules have changed over the years.
Do you need to flush the system during a swap?
Yes. A system cleanse is a standard part of every boiler swap we carry out, because sludge from the existing pipework can quickly damage a new boiler's heat exchanger if it is not removed first.
Can I upgrade the boiler size during a swap?
We check the correct size for your property's current hot water and heating demand rather than automatically matching the old boiler's output, and will explain if a different size is more appropriate.
What if my gas pipe is too narrow for a new boiler?
We identify this at survey and quote the pipe upsizing as part of the fixed written price, rather than discovering it mid-installation and adding cost afterwards.
How much does a boiler swap cost in Liverpool?
New boilers are fully fitted from £1,299, with the exact price depending on the model chosen and whether any gas pipe or flue work is needed, all confirmed in writing before work starts.
Do you cover boiler swaps across Merseyside?
Yes, across Liverpool, Knowsley, Halton and St Helens. We answer the phone seven days a week, 8:30am to 5:30pm, and can often arrange a swap quickly if you currently have no heating or hot water.
Still not sure? Send us the details or ring 07523 738285.
Your next step
Get Your Fixed Price in Writing
Send us the details and we'll come back with a clear price, or ring now if you're without heating or hot water.
- Gas Safe registered no. 576059 · licence no. 3715984
- 25 Bardley Cres, Tarbock Green, Liverpool L35 1RJ
- 07523 738285 · 0151 384 5908
- info@harrisonejonesheating.co.uk
- Mon–Sun, 8:30am–5:30pm
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Or call us direct on 07523 738285 · 0151 384 5908