Boiler Servicing & Repairs
Keep your boiler running safely and efficiently all year with an annual service or a fast repair from your local Gas Safe team.
Done properly, by a local team
Annual servicing
Keeps your boiler safe, efficient and within its guarantee terms.
Guarantee protection
An annual service is a condition of most manufacturer guarantees — it keeps yours valid.
Fast local repairs
A Merseyside team who can get to you quickly when something goes wrong.
What an annual service actually involves
A service is a set of measurements, not a look and a wipe over. The engineer runs the boiler up to temperature and puts a calibrated flue gas analyser into the sampling point, reading carbon dioxide, oxygen and carbon monoxide to work out the combustion ratio and confirm the burner sits inside the band the manufacturer specifies. Gas working pressure and gas rate are checked. The case comes off so the burner, heat exchanger and flue ways can be inspected for debris and corrosion, the condensate trap is removed and flushed, and the ignition and flame-sensing electrodes are checked for condition and gap. The case seal matters more than most people expect, because a poor seal on a room-sealed appliance can draw products of combustion back through the boiler. Expansion vessel charge pressure is tested and re-pressurised if it has dropped, the safety devices are proved, and the flue terminal and its clearances are checked from outside. Anything found is explained before work is done.
Servicing is a condition of most manufacturer guarantees
Most boiler guarantees are conditional, and the two conditions people fall foul of are registration and servicing. The Benchmark checklist at the back of your manual should have been completed at commissioning, and the appliance registered with the manufacturer within about a month of installation. After that, manufacturers generally require an annual service by a Gas Safe registered engineer, recorded on the Benchmark service interval record. If that record has gaps, a manufacturer can decline a claim on a part that would otherwise have been covered, and a heat exchanger or gas valve is not a cheap thing to be arguing about. Some manufacturers also ask for an engineer trained on that particular appliance, so read your guarantee terms rather than assume. Keep the manual, the checklist and every service record together in one place. As a Worcester Bosch Accredited Installer we can offer guarantees of up to 12 years on qualifying Greenstar models. Worcester's longest terms are conditional: a Worcester Greenstar system filter fitted at installation, the boiler registered with Worcester within 30 days, and an annual service every year of the term. Shorter-guarantee models in the range carry five or ten years, so check the term against the specific boiler.
System water, sludge and filters in a soft-water area
Most of Merseyside is supplied with soft to slightly hard water from upland reservoirs, so scale in a combi's plate heat exchanger drives fewer breakdowns here than it does further south, although supplies out towards Cheshire West can be harder. What we see constantly instead is magnetite: black iron oxide sludge produced as steel radiators corrode from the inside. It settles in the bottom of radiators, blocks the narrow waterways of a modern heat exchanger, and shortens the life of pumps and diverter valves. BS 7593:2019, the code of practice for treating system water, asks for inhibitor strength to be checked at each annual service, a water test or re-dose at least every five years, and a permanent in-line filter to catch magnetic and non-magnetic debris. If you have a magnetic filter, cleaning it out is part of the service. If you have not, on an older system that is usually money better spent than another chemical top-up.
Common faults, and what a fault code really tells you
A fault code narrows the search, it does not name the part, and the same code can mean different things on different models, so check your own manual before anyone orders anything. Worcester's EA is a loss-of-flame code. D5 is a condensate code, a condensate pump or drainage fault on most Greenstar models, and on some Greenstar CDi models a service-due reminder driven by burner hours rather than a fault at all. Either can show up in a cold snap when the condensate pipe has frozen, which is far more often the cause than a failed boiler. Vaillant's F28 is ignition failure and F75 means the boiler sees no pressure change when the pump starts, which often turns out to be the pressure sensor or a seized pump rather than a leak. Ideal's F1 is low water pressure and L2 an ignition lockout. Away from codes, the two patterns we attend most are pressure that keeps falling, which points at a weeping radiator valve, a joint under a floor, or an expansion vessel that has lost its charge; and hot water working while the heating does not, which usually means the diverter valve. Repeated lockouts should be investigated rather than reset over and over.
Frozen condensate: the winter callout we get most
A condensing boiler produces mildly acidic waste water that drains away through a plastic pipe. Where that pipe runs outside, which is common on terraced streets and on flats where the boiler sits against an external wall, a cold night can freeze it. The blockage backs up, the boiler stops firing to protect itself, and you are left with a lockout code. This one you can often deal with yourself. Turn the boiler off, find the white or grey plastic pipe outside, and pour warm, not boiling, water along it from the top down; boiling water can crack the pipe or the fittings. Only do this if you can reach the pipe safely from the ground, never from a ladder, a flat roof or a window, and if you cannot reach it, ring us instead. When it clears, reset the boiler and it should fire. If it freezes every cold spell, the pipe is the fault, not the weather. The remedies are increasing the external section to 32mm, fitting weatherproof lagging, cutting the external run back, which Worcester limits to three metres on its own appliances, or re-routing it internally into a soil stack. Trace heating, which warms the pipe automatically in cold weather, is an option where the run cannot be moved.
Landlords: the 12-month gas safety check explained
If you let a property, the Gas Safety (Installation and Use) Regulations 1998 require every gas appliance and flue you are responsible for to be safety checked every 12 months by a Gas Safe registered engineer. You must give the record to existing tenants within 28 days of the check, to new tenants before they move in, and keep copies for at least two years. Since 2018 the check can be done up to two months early without losing your original anniversary date, which makes scheduling a portfolio far easier, though if you use that flexibility, keep each record until two further checks have been carried out, so the run of dates can be evidenced. Two things catch landlords out. First, a safety check is not a service: it confirms the appliance is safe, but it does not include stripping and cleaning it, so many landlords book both together. Second, since 1 October 2022 rented homes in England must have a carbon monoxide alarm in every room used wholly or partly as living accommodation that contains a fixed combustion appliance, a boiler, a fire or a log burner, with gas cookers excepted. Our Gas Safe registration number is 541116, and you can check it on the Gas Safe Register.
When a repair is worth it, and when it is not
The honest test is the cost of the repair set against the age, condition and remaining guarantee of the appliance. A boiler under ten years old with a decent service history and a failed fan, pump or diverter valve is normally worth repairing. The sums change when it is twelve or fifteen years old, when the failure is the primary heat exchanger or the gas valve, when parts are becoming obsolete, or when it is the third repair in two years. Any gas boiler fitted before April 2005 is likely to be non-condensing, and the efficiency gap against a modern condensing appliance is wide enough to change the decision on its own. Our replacement boilers are £2,000 to £2,850 fitted depending on the appliance and the work involved, and any new installation must meet the current Building Regulations standard for controls and efficiency. Finance is available, subject to status, and the options are set out on our finance page. We will tell you plainly when a repair is still the better call.
Simple, from quote to comfort
- 1
Tell us what it's doing
Describe the fault or book your annual service. We'll tell you what we can over the phone.
- 2
Pick a date that suits you
Choose a day that works. We confirm the visit and the call-out cost up front.
- 3
Gas Safe diagnosis
Our engineer finds the fault and tells you the cost before doing the work — no surprises.
- 4
Benchmark & paperwork
Service records completed, and we flag anything starting to wear before it becomes a breakdown.
Related services
Common questions
How often should a boiler be serviced, and when is the best time to book?
Once a year, and the same time each year, so the interval stays at twelve months and your guarantee record has no gaps. Late summer and early autumn are the sensible window: faults are found while the heating is not needed, parts are easier to get, and you are not waiting behind a queue of no-heat calls in December. If you have just moved in and have no paperwork, book one anyway so you have a baseline.
How do you charge for a service, and do I have to commit to anything?
You pay for the visit or the repair you actually have. We confirm the price with you before we book anything in, and if parts are needed we tell you what they cost before we order them. If the service turns up a fault, the engineer explains what it is and what putting it right involves before going any further, so nothing gets done that you have not agreed to.
Will a missed service invalidate my boiler guarantee?
It can. Most manufacturers make an annual service by a Gas Safe registered engineer a condition of the guarantee, recorded on the Benchmark service interval record in your manual. A missed year gives the manufacturer grounds to decline a claim on an expensive part. If you have already missed one, get the boiler serviced and the record signed rather than leaving it, then check your own guarantee terms, because manufacturers differ on how they treat a gap.
Is a landlord gas safety certificate the same as a boiler service?
No. A landlord gas safety record, still widely called a CP12, confirms that appliances, flues and pipework are safe at the time of the check, and it is a legal duty every 12 months. A service is maintenance: the boiler is opened, cleaned, measured and adjusted. One is about safety, the other about condition and efficiency, and only the service keeps your manufacturer guarantee valid. Most landlords we work with book the two on the same visit.
My boiler has locked out with a fault code. What can I check myself?
Check the code in your manual first. If it is a loss-of-flame code on a cold morning, the likely cause is a frozen condensate pipe. Turn the boiler off, pour warm water along the outside pipe, never boiling, then reset, but only if you can reach the pipe safely from the ground. If the pressure gauge is under about 1 bar, the boiler may need topping up using the filling loop, following your manual. If it locks out again after a reset, stop and ring us on 0151 440 2000.
At what point does a repair stop being worth paying for?
When the repair is a large share of a replacement and the boiler is near the end of a typical ten to fifteen year life, or when parts are becoming hard to source. One serious failure on an old appliance is usually the point to stop spending. Our replacement boilers run from £2,000 to £2,850 fitted, so a four-figure repair on a fifteen-year-old boiler rarely makes sense. Finance is available, subject to status, and we will give you both figures before you decide.
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