The vast majority of boiler call-outs come down to a handful of recurring faults. After more than a decade of working on boilers, David can usually narrow the problem down to one or two likely causes the moment you describe what's happening over the phone — which means he turns up with the right spares already on the van.
Tell him what your boiler's doing (locked out with an error code, leaking, no hot water, kettling, cold radiators) and he'll tell you over the phone what it's most likely to be, what it'll cost roughly to fix, and whether it's a same-day job or one that needs a return visit. No diagnostic fee charged just for the conversation. The £85 diagnostic only kicks in if he comes out — and that £85 is waived if you proceed with the repair on the same visit.
Boiler faults aren't random — they cluster around a small number of failure modes. Recognising the symptoms tells you (and David) which way to start looking.
Low pressure (gauge below 1.0 bar) is by far the most common single complaint. The cause is almost always one of three things: a slow leak somewhere in the system (joint, radiator valve, towel rail), a worn pressure relief valve dripping outside the property, or a failed expansion vessel that's lost its charge and can't accommodate water expansion when the system heats. The first two are easy to spot once you know to look. Expansion vessel failure is sneakier — gauge climbs as the system heats, then drops below cold pressure when it cools.
Specific manufacturer error codes tell you exactly what the boiler thinks is wrong. F1 on a Vaillant is low pressure. EA on a Worcester is ignition lockout. A1 on a Baxi is low pressure. E168 on a Glow-worm is a general fault flag. L2 on an Ideal is ignition lockout. F22 on a Vaillant is low pressure. Every code corresponds to a specific failure category, and David has seen all of them dozens of times.
No heat but hot water (or vice versa) is, in 90% of cases, a stuck diverter valve. The diverter is the mechanical or motorised component that switches flow between the central heating circuit and the hot water circuit. When it sticks, you get one but not the other. Diverter swap is a 90-minute job with the part on the van.
Kettling, banging or gurgling from inside the boiler is sludge. Iron oxide builds up in the heat exchanger, creates hot spots, and water boiling against those hot spots produces the kettle-on-the-hob sound. Severe kettling means the heat exchanger may be permanently damaged — minor kettling can usually be cured with a system flush and fresh inhibitor.
Pump failures show as no flow in the system — radiators stay cold despite the boiler firing, hot water comes through fine on a combi (pump uncoupled in DHW mode). Most domestic boilers use a Grundfos UPS pump. Replacement is a same-day job.
PCB failures on older boilers (typically 10+ years) mean the brain has died. The boiler either won't fire at all or behaves erratically (random lockouts, displaying nonsense, ignoring the thermostat). PCB replacement is possible but at this age it's worth a frank conversation about repair vs replace — David will tell you straight which way the maths goes.
Boiler emergencies don't pick a polite time of day. The good news: most are fixable same-day if you call early enough.
David's emergency rule is simple — if you phone before lunchtime with a no-heat or no-hot-water situation, he'll aim to be on-site the same afternoon. Call after lunch and it'll usually be next-day unless the diary has space (often does on a quiet weekday). For genuine winter emergencies — vulnerable household, no heat in February, frozen condensate — he'll squeeze you in same-day where humanly possible.
What he can't do is be everywhere at once. If David's already on a job when you call, you'll get told straight away whether he can fit you in, and a realistic time. No fake ‘within the hour’ promises that turn into 4pm.
The most expensive boiler repair is the one done on a unit that should have been replaced. Equally, the most wasteful boiler replacement is the one done on a boiler that just needed a service and a new diverter. Knowing which side of that line your boiler sits on matters.
Repair almost always makes sense if: the boiler is under 8 years old, the fault is a single component (PRV, vessel, diverter, pump, motorised valve), the parts are readily available, and the rest of the boiler shows no signs of wider deterioration.
Replace makes more sense if: the boiler is over 12 years old, the fault is a major component (heat exchanger, PCB on an old model, fan), there have been two or three significant faults in the last couple of years, or parts for that specific model are getting hard to source. At that point you're throwing good money after bad, and the gas-bill savings from a new condensing unit will pay back the install cost in 4–6 years.
Service first, decide later for any boiler showing intermittent faults but otherwise running. A proper service catches the small problems — sooted burner, low expansion vessel, blocked condensate — that imitate bigger faults. Often the ‘dying’ boiler turns out to have years left in it after a £85 service.
Most boiler repairs across West London come down to the same dozen jobs done in different combinations. The components that actually fail are well-known, well-documented, and well-stocked.
Pressure relief valve replacement — a valve that's perished and dripping outside the property. £140–£180 fitted, parts on the van.
Expansion vessel re-pressurise or replace — diaphragm vessel that's lost its charge. Re-pressurising is included in a service; replacing the vessel is £180–£280 depending on access.
Diverter valve replacement — sticking diverter causing heat-or-water issues. £220–£320 fitted depending on boiler model. Worcester and Vaillant ones are well stocked; some Baxi and Ideal models need next-day delivery.
Pump replacement — Grundfos UPS or equivalent. £240–£300 fitted. Same-day on the van for the most common models.
Motorised valve (Honeywell V4073A and Drayton equivalents) for system and regular boilers — £180–£240 fitted.
Condensate trap and pipe re-route for frozen-condensate winter lockouts — £80–£140 depending on what's needed.
Less common parts (PCBs, brand-specific heat exchangers, full burner assemblies) are ordered in for next-day fitting. David's quote always splits the parts cost from the labour cost so you can see exactly what you're paying for.
Repairing a domestic gas boiler is regulated work under the Gas Safety (Installation and Use) Regulations 1998. Only an engineer registered with the Gas Safe Register may legally carry out repairs that involve the gas circuit, the combustion side, the flue, or any safety device on the boiler. Anyone touching those components without Gas Safe registration is operating illegally, and any work signed off without registration is void for warranty and insurance purposes.
David is fully Gas Safe registered and carries his ID card on every callout. The card has his photo, registration number, the categories of gas work he's certified for, and an expiry date. You can verify any engineer's registration directly at gassaferegister.co.uk by entering their number — and you should, especially if it's an engineer you haven't used before. Every repair David carries out is logged correctly so it stands up if you ever need to refer back to it.
Same-day for no-heat and no-hot-water emergencies if you call before lunchtime. Phone after lunch and it's typically next-day, unless the diary has space (often does on quiet weekdays). For non-urgent repairs we book within 48 hours. David tells you straight on the call what slot he can offer — no fake same-hour promises that turn into 4pm.
£85 for the first 30-minute diagnostic visit. The £85 is waived if you proceed with the repair on the same visit, so most customers effectively pay zero diagnostic. A written quote is given before any chargeable work begins. No diagnostic fee is charged just for a phone conversation — describe the symptoms and David will tell you over the phone what it's most likely to be.
Honest answer: if your boiler is over 12 years old, has had two or three significant faults in the last couple of years, or needs a major part like a heat exchanger or PCB, replacement is often cheaper in the long run. David will tell you that openly and price both options. Equally, if your boiler is fundamentally sound and just needs a single component, he'll say so and not push a new boiler on you. The maths is rarely close — usually the answer is obvious once the diagnostic is done. Other plumbing work Clive covers from the same Ealing base: emergency plumbing, drain unblocking, pipework and repipes, tap and outlet installation, water tank installation, leak detection, toilet installation, white goods plumbing, kitchen plumbing, hot water cylinder installation and bathroom installation.
Pressure relief valves, expansion vessels, the most common diverter valves (Worcester, Vaillant, Baxi), common pumps (Grundfos UPS), motorised valves (Honeywell V4073A and Drayton equivalents), thermocouples, common flue seals and condensate trap kits. Less common parts — PCBs, brand-specific heat exchangers, full burner assemblies — are ordered in and a return visit booked, usually within 24–48 hours.
Every major UK domestic gas boiler brand: Worcester Bosch, Vaillant, Baxi, Ideal, Glow-worm, Vokera, Potterton, Main, Alpha, Ferroli, Biasi, Heatline, Halstead and most others. If your boiler runs on UK domestic mains gas, David can fix it. Specific models or unusual European boilers — phone first and he'll tell you straight whether he covers it. The full gas-side service list David covers: boiler installation, boiler servicing, central heating installation, central heating repair, gas safety checks, gas leak detection, gas cooker installation, gas fire servicing and power flushing — all Gas Safe registered, all run from the same Ealing base.
+
%
+
%
For a free, no-obligation quote on a boiler repair anywhere in boiler repairs in Ealing, boiler repairs in Acton, boiler repairs in Hanwell, boiler repairs in Greenford, Northolt, Perivale, Southall, boiler repairs in West Ealing, Park Royal, boiler repairs in Pitshanger, Brentham, North Ealing, boiler repairs in South Ealing or anywhere else across the W postcodes — give David a ring directly. Describe what your boiler is doing and he'll tell you over the phone what it's most likely to be, what the part typically costs, and whether it's a same-day fix or one that needs ordering.
David also covers boiler repairs across the rest of the borough — boiler repairs in Boston Manor, boiler repairs in Brentford, boiler repairs in Ealing Common and boiler repairs in Northfields — all served from the same Ealing base, same engineer, same fixed-price quotes.
Quotes are always free and always in writing before any chargeable work begins. If David doesn't think a repair is worth doing — for example, if your boiler is approaching the end of its life — he'll tell you that openly and price both repair and replacement so you can decide.