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No heat, no hot water, a leak, a lockout or a boiler that keeps kettling across Eltham’s SE9 homes. Find verified Gas Safe engineers below, each checked before listing. Skip to verified engineers ↓
✅ Checked before listing — identity, insurance, trading presence, Gas Safe (where relevant).
How we verify →
✅ Workmanship guarantee badges on listings — 1, 3, 6 or 12 months
⚠️ Smell gas or suspect carbon monoxide? Leave the property and call the National Gas Emergency Service on 0800 111 999 from outside — don’t touch switches or use flames. Gas & CO safety →
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Coverage: Eltham and around in SE9 — Eltham Town Centre, Well Hall, Middle Park, Horn Park, Avery Hill, New Eltham and Mottingham, within the Royal Borough of Greenwich. SE9 is a postcode guide, not an official Eltham boundary.
What this covers: diagnosing and repairing a fault on a domestic gas boiler — no heat or hot water, leaks, pressure loss, error codes, noise and lockouts — by a Gas Safe registered engineer.
Not sure it’s this you need? Cold radiators on a working boiler are on Central Heating Repair; a routine check-up on Boiler Servicing; a boiler past economic repair on Boiler Installation.
Costs: indicative ranges are under What it costs below — editorial estimates only.
Availability: each engineer sets their own hours, shown on their profile.
Jump to: Common faults · The first visit · Repair or replace · Hard water & sludge · Flats & communal heat · The flue question · Safety first · Who’s responsible · Costs · FAQs
What actually goes wrong — and why diagnosis matters
Most boiler call-outs come down to a handful of causes, and the skill is telling them apart rather than swapping parts until the light goes green. No heat or hot water can be a failed diverter valve, a seized pump, a faulty thermostat or a gas-supply issue. Pressure that keeps dropping points to a leak on the sealed system, or a failing expansion vessel or pressure-relief valve. A boiler that fires then locks out is often ignition, a flame-sensing fault or a blocked or frozen condensate pipe — the last of these common on cold mornings where a condensate run is exposed outside, as it often is on inter-war Eltham semis with a boiler in a garage, utility or external-wall kitchen. Banging, gurgling or a kettle-like rumble — “kettling” — usually points to debris or scale on the heat exchanger, not the boiler as a whole.
That last group is the one homeowners most often misread, because the noise is at the boiler but the cause is in the system water. Our Boiler Fault Codes guide helps you describe the symptom before you call.
The first visit — how a good engineer works
A methodical engineer works in sequence rather than guessing: read the fault code, check system pressure, confirm the thermostat is actually calling for heat, check the condensate route, look for visible leaks, and only then move to the gas-side and combustion checks — which only a Gas Safe registered engineer may carry out. Some faults are fixed on the first visit; others need a manufacturer-specific part ordered, so the engineer should tell you what’s done and what’s scheduled before leaving, and quote accordingly.
Repair or replace — an honest boundary
Not every fault is worth repairing. A cheap, common part on a boiler still under warranty is an easy call. A major component — heat exchanger, gas valve, fan or PCB — on an older, inefficient boiler that’s already failing in other ways can cost enough that replacement makes more sense over a few years. Age, parts availability, breakdown history and efficiency all feed in. A verified engineer should lay that out plainly rather than push you one way; if the answer is replacement, that’s a separate job — see Boiler Installation — and our Boiler Repair or Replace guide walks through the trade-offs.
Hard water, sludge and Eltham’s older systems
Two different problems foul a boiler, and they’re often confused. Limescale is calcium scale from hard water; it forms in the hottest part of the system — the heat exchanger and a combi’s hot-water side — and cuts heat transfer, which is why Eltham’s hard supply matters. Magnetite sludge is black iron oxide from internal corrosion; the British Standard for system water, BS 7593:2019+A1:2024, notes it settles in low-flow areas such as radiators and can also coat a heat exchanger, and that scale and sludge together form a very hard deposit and cause boiler noise. Thames Water confirms the whole region’s water is hard, so both mechanisms are in play.
Eltham’s mix of inter-war and older housing means many systems have decades of corrosion behind them. A repair that keeps recurring — a pump that fails again, a radiator that won’t heat, a boiler that kettles — is often a symptom of a dirty system rather than one faulty part. One caution: repeatedly topping up a system that keeps losing pressure isn’t a fix, because each refill introduces fresh oxygenated water that accelerates internal corrosion — the leak or vessel fault needs finding. The lasting fix is cleaning and protecting the water, addressed on Boiler Servicing and Central Heating Repair, not just replacing the component that failed.
Flats and communal heat — when it isn’t a boiler at all
In some Eltham flats, conversions and newer blocks, a loss of heating or hot water in one flat while the rest of the building stays warm can be a communal-heating or heat-interface-unit (HIU) fault rather than a private gas boiler. That routes to the building’s plant operator or managing agent, not a boiler engineer — so it’s worth confirming what your home actually has before booking. Where there is a private gas boiler, the guidance on this page applies.
The flue question — repairs that tip into a boiler move
Sometimes a repair reveals the boiler needs replacing, and a new boiler often means a new or relocated flue — and in parts of Eltham that isn’t a free choice. Eltham has several conservation areas, including Eltham Palace, Eltham Green, Well Hall Pleasaunce and the Progress Estate, and some listed and locally listed stock. The Planning Portal sets out that in a conservation area a flue should not be fitted on the principal or side elevation if it fronts a highway; on a listed building, Listed Building Consent is likely needed even where permitted-development rights would otherwise apply; and for flats, those rights don’t apply at all. A verified engineer who works in Eltham will flag this before assuming a flue can go where it’s easiest.
Safety first
Gas work is restricted by law, and a boiler fault can involve gas or carbon monoxide — so the safety steps come before everything else.
If you smell gas or suspect a leak, follow the National Gas Emergency Service steps in order:
- Don’t switch anything electrical on or off, don’t use a naked flame, don’t smoke, and don’t use a mobile near the suspected leak.
- Open doors and windows if it’s safe to do so.
- If the meter control handle is safely reachable, turn the gas off at the meter — unless the meter is in a cellar.
- Leave the property if the smell is strong or you feel unwell.
- Call the National Gas Emergency Service on 0800 111 999 from outside, and don’t go back in until an engineer gives the all-clear.
Carbon monoxide is a colourless, odourless gas a poorly-running boiler can produce. London Fire Brigade says CO comes from boilers and other fuel-burning appliances that are faulty, badly fitted or poorly maintained, or where flues and vents are blocked, and recommends an audible CO alarm — not a colour-change indicator — in any room with a fuel-burning appliance, audible throughout the home. Warning signs at the boiler include sooty staining and a lazy yellow or orange flame instead of a crisp blue one. A CO alarm is a second line of defence, never a substitute for annual servicing. If you suspect CO, get into fresh air and call 0800 111 999.
Only a Gas Safe registered engineer may work on a boiler or its gas pipework. Gas Safe Register is the official list of businesses and engineers legally allowed to do gas work — ask to see the seven-digit Gas Safe ID card before any gas work starts. Wet work — radiators and water pipes — doesn’t need registration, but the boiler, its combustion and flue, and the gas connection to it do.
Renting or in a council home? Who arranges the repair
Royal Greenwich council tenant. Boiler and heating repairs aren’t a private booking. Report a loss of heating or hot water through the council repair route — urgent on 020 8921 8900 in the day, or 020 8854 8888 at other times.¹ For a gas leak, call National Gas on 0800 111 999, not the council.
Private tenant. Your landlord is responsible for the boiler. Under the Gas Safety (Installation and Use) Regulations 1998, HSE requires landlords to keep gas appliances and flues they provide maintained by a Gas Safe registered engineer and to arrange an annual gas safety check, giving you a copy of the record within 28 days. Report a broken boiler to your landlord in writing. Royal Greenwich treats a suspected carbon-monoxide leak, and no hot water, as serious hazards you can report straight to its Residential Services team on 020 8921 8157; no heating, by contrast, is listed as a less serious issue — contact the landlord first in writing and escalate to Residential Services only if they don’t respond within 14 days or don’t carry out the repair.² For any gas or CO emergency, call National Gas on 0800 111 999 first.
What a boiler repair costs in Eltham
A rough orientation to sense-check a quote — not a price list. No official pricing exists; always get written quotes.
| Job | Make-safe / diagnostic | Full repair range |
|---|---|---|
| Diagnostic call-out / first hour | £70–£150 | rolled into the job |
| Common part (thermostat, valve, sensor) | assessment first | £120–£300 |
| Major part (fan, PCB, pump, heat exchanger) | assessment first | £250–£600+ |
| Boiler leak — isolate and make safe | £120–£250 | quote after parts confirmed |
| Frozen/blocked condensate — thaw and clear | £90–£180 | n/a |
| Out-of-hours / weekend call-out | £120–£250+ | additional labour rate |
Editorial estimate only — not regulated rates, market data or a cost survey. Actual quotes vary by boiler make, part, access and timing. Eltham is inside the London ULEZ, so a non-compliant van may carry the £12.50 daily charge; ULEZ rules can change, so check the current position.
Why directory-listed engineers
A boiler is the one repair where an unqualified “engineer” is genuinely dangerous, so checking credentials in advance matters more here than anywhere. Every engineer listed for Eltham is checked for identity, insurance and trading presence before going live and rechecked annually, and where gas work is involved we confirm Gas Safe registration directly — you should still ask to see the ID card on the doorstep. These listing checks are administrative and don’t replace your own checks or guarantee workmanship. You contact the engineer directly: no lead fee, no per-enquiry charge, and no pay-to-play ranking, with any Sponsored placement labelled. Workmanship guarantees of 1, 3, 6 or 12 months are set by the plumber, vary in scope and aren’t insurance-backed unless stated; your Consumer Rights Act 2015 rights still apply.
Frequently asked questions
Sometimes it’s just re-pressurising.
But a pressure drop that returns usually means a leak on the system or a failing expansion vessel or relief valve, which needs finding.
Repeatedly topping up isn’t a fix.
Each refill adds oxygenated water that speeds up corrosion.
That “kettling” usually points to limescale or sludge on the heat exchanger.
In hard-water Eltham, scale is common.
Recurring noise often means the system water needs cleaning and protecting, not just a part swap.
On cold days, a frozen condensate pipe is a common cause.
That’s especially true where the run is exposed outside — often on inter-war semis with the boiler in a garage or on an external wall.
It can usually be thawed and cleared.
But the run may need re-routing or insulating.
Possibly not.
In flats and newer blocks it can be a communal-heating or heat-interface-unit fault.
That usually routes to the building operator or managing agent rather than a private boiler engineer.
Confirm what your home has first.
No.
Only a Gas Safe registered engineer may work on a boiler or its gas pipework.
Ask to see the seven-digit Gas Safe ID card before gas work starts.
Not a private engineer.
Report it through the council repair route.
Urgent repairs go to 020 8921 8900.
Out-of-hours emergencies go to 020 8854 8888.
A gas leak goes to National Gas on 0800 111 999.
Boiler repair across Eltham — areas covered
Eltham sits within the Royal Borough of Greenwich, alongside Mottingham, New Eltham, Well Hall, Avery Hill, Kidbrooke, Falconwood and Blackheath. Browse all local coverage from the Royal Greenwich plumbers hub.
Related services in Eltham
Boiler Servicing · Boiler Installation · Central Heating Repair · Emergency Plumber · General Plumbing
Related guides
Boiler Fault Codes · Boiler Repair or Replace · Combi vs System Boiler · London Hard Water Guide
A broken boiler needs the cause found, not just the light reset. Get a Gas Safe engineer who reads the fault, checks the water and tells you honestly whether it’s a repair or a replacement. Guarantees vary; confirm with your engineer.
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Source provenance
Regulatory and safety guidance on this page is drawn from primary UK sources: the Health and Safety Executive (landlord gas-safety duties under the Gas Safety (Installation and Use) Regulations 1998), Gas Safe Register (legal requirement for gas work), the National Gas Emergency Service (0800 111 999), London Fire Brigade (carbon monoxide guidance), Thames Water (hard-water region), the Royal Borough of Greenwich (council repair routing and private-rented escalation) and the Planning Portal (flue rules in conservation areas). BS 7593:2019+A1:2024 is the British Standard code of practice for domestic heating-system water. Cost figures are an editorial estimate only — not regulated rates or official market data.
Last reviewed: July 2026 by Adiel Khan — SFEDI-accredited business advisor, 20+ years’ experience (South East Enterprise Ltd) and operator of VerifiedPlumbers. LinkedIn ↗
This page is checked for compliance and regulatory accuracy against the bodies cited on it — the National Gas Emergency Service, Gas Safe Register, the Health and Safety Executive, London Fire Brigade, Thames Water, the Royal Borough of Greenwich and the Planning Portal. Source links are provided within this page where relevant.
Sources & further reading
¹ Royal Borough of Greenwich — Request a repair to your council home
² Royal Borough of Greenwich — Report a problem with a private rented home
- National Gas — Emergency contacts
- Gas Safe Register — official register of gas engineers
- HSE — Gas safety: landlords and letting agents
- London Fire Brigade — Carbon monoxide safety
- Thames Water — Hard water
- BSI — BS 7593:2019+A1:2024 (code of practice for domestic heating-system water)
- Planning Portal — Flue, chimney or soil and vent pipe: planning permission
- Royal Borough of Greenwich — Conservation areas: maps and adopted character appraisals