Central Heating
For London Homes —
Designed, Fitted, Balanced.
Whether it's a full first-time install, a system upgrade from an old vented cylinder to a modern unvented one, additional radiators for an extension, or a controls overhaul that finally makes the upstairs actually warm — we design, fit and commission complete central heating systems in London properties.
Central heating done as a system, not a pile of parts.
A central heating system is a designed hydraulic circuit — boiler output, pipe sizes, radiator emitter capacity, pump duty, expansion volume, controls topology and hot-water storage all have to be sized against each other. Get any one wrong and you get the classic complaints: cold radiators upstairs, tepid showers when the heating is on, boiler locking out on high return temperatures, huge gas bills for a lukewarm house.
Chelsea Plumbing & Heating Co. designs and installs full central heating systems across London and the Home Counties. That includes new-build first-fixes, complete system replacements in older properties, extension add-ons, cylinder upgrades (vented to unvented, G3-qualified), controls overhauls, and remedial work on systems that were never properly commissioned by whoever fitted them originally.
This service is for homeowners planning a boiler replacement who also want the rest of the system brought up to modern standard, extension projects that need heating added to new rooms, landlords whose properties are underperforming on EPC ratings, and anyone whose heating 'just doesn't work properly' and wants the actual cause diagnosed rather than another patch job.
The single biggest driver of comfort and running cost is not the boiler brand — it's the system design. Correct pipe sizing, correctly sized radiators for each room's heat loss, a proper commissioning balance, and modern controls with weather compensation typically save 25–40% on running costs versus the same boiler installed onto an untouched older circuit.
Why bolt-on heating jobs cost you twice.
The most common failure mode we're called to is a new boiler fitted onto an old, sludged circuit with no filter and no flush. Within six months the new heat exchanger is blocked with black magnetite from the old radiators, the manufacturer refuses the warranty (no Benchmark, no filter), and the homeowner is looking at another £2,000+ appliance three years early.
The second is extension radiators bolted onto a system that wasn't sized for them. The new rads work, but the far-end original ones now don't — because the pump can't drive flow through a longer, wider circuit. What was meant to add heat has removed it from the rooms that used to be warm.
The third is 'more powerful boiler = warmer house' logic. Wrong. If the pipework, radiators or controls can't deliver the output the boiler can produce, you've just paid for a bigger appliance to short-cycle and wear out faster.
- ×Adding radiators without recalculating pump duty or resizing pipework — new rads work, old ones go cold.
- ×Fitting a new boiler onto a sludged circuit with no flush and no magnetic filter — voids warranty, kills the new heat exchanger.
- ×Choosing radiator size on aesthetics alone — a designer radiator with 40% less output than the room needs will never heat that room.
- ×Leaving TRVs sitting on manufacturer default — no zoning, no efficiency, and one thermostat controlling the whole house.
- ×DIY unvented cylinder work — legally requires a G3-qualified engineer. Non-compliant installs are uninsurable.
- ×Using microbore pipework decisions from 30 years ago as the template for a modern high-efficiency system.
A methodical system,
not a rushed callout.
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01Survey & heat-lossOn-site survey, room-by-room heat-loss calculation, existing system audit, pipework and controls assessment.
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02System designBoiler sized, radiators specified per room, cylinder sized (if applicable), controls topology chosen, fixed written proposal issued.
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03InstallOld components stripped, pipework upgraded where needed, new boiler, radiators and controls fitted.
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04Flush & balancePowerflush of retained pipework, magnetic filter fitted, inhibitor dosed, every radiator balanced individually.
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05Commission & guaranteeFull system commissioning, controls programmed, Benchmark completed, 12-month workmanship guarantee issued in writing.
Concrete outcomes,
not vague promises.
Comfort in every room
Radiators sized to room heat-loss and balanced individually — no more 'the back bedroom never warms up' in January.
25–40% lower running costs
Weather compensation, correctly-sized boiler, low return temperatures and zoned controls deliver measurably lower bills.
Warrantied end-to-end
Boiler warranty (7–10 years), radiator warranties (typically 10 years on quality brands), plus our 12-month workmanship cover.
G3 Unvented qualified
Fully qualified for unvented cylinder work — legally required, and the difference between mains-pressure hot water and a poor shower.
One engineer, one plan
Ian designs it, Ian fits it, Ian commissions it. No design-vs-install communication gaps that cost you money later.
Coordinated with other trades
For extension and renovation projects we coordinate with builders, electricians and kitchen/bathroom fitters — first-fix and second-fix scheduled properly.
Photographs from
actual jobs.
Real installations, repairs and diagnostics carried out by Ian across London and the Home Counties. No stock photography.
Central heating scope we cover.
Central heating is a broad category — here's the specific work we do most often across London properties, from Victorian terraces to modern flats to landlord portfolios.
Full system replacements
Boiler + radiators + controls + pipework flush + magnetic filter on properties where the existing system is at end of life. Sized against a fresh heat-loss survey, not just copied from what was there before.
Vented-to-unvented conversions
Removing loft header tanks and vented cylinders, installing a G3-compliant unvented cylinder for mains-pressure hot water throughout — including all statutory discharge pipework and tundish arrangements.
Extension add-ons
New radiator circuits sized to the extension's heat loss, pump duty re-checked, controls extended, and existing rooms re-balanced so nothing loses output.
Radiator upgrades & swaps
Old single-panel radiators swapped for double-panel or vertical designer units with correct output. TRVs fitted, chrome or brass valve pairs supplied, existing pipework re-routed where needed.
Controls & zoning
Smart thermostats (Nest, Hive, Tado, Honeywell Evohome), weather-compensation sensors, room-by-room TRVs, and multi-zone valve arrangements for properties with clearly separated heating demands.
Hot-water cylinders
Direct and indirect unvented cylinders, sizing based on peak simultaneous demand (bath + shower + basin), G3-qualified installation and annual servicing.
System flushing & inhibitor dosing
Full powerflush of existing circuits before a new boiler is added — the non-negotiable step that keeps manufacturer warranties intact.
Pipework upgrades
Microbore to 15/22mm upgrades where flow is inadequate, chrome pipework for exposed installs, and buried pipework re-routing during extension or refurbishment work.
How much does a full central heating install cost in London?
A full new system with boiler, radiators, controls, pipework and flush typically runs from £5,500 upwards on a 2–3 bedroom property, depending on scope. Every project is priced in writing after a survey — no hidden extras.
How long does a full system install take?
A straightforward 2–3 bedroom full system replacement is typically 3–5 working days. Extension add-ons and cylinder conversions can vary from 2 to 6 days depending on pipework routing.
Do you work on unvented cylinders?
Yes — Ian is G3-qualified (the legally-required qualification for unvented hot-water cylinder installation, commissioning and servicing). Every unvented install includes the correct discharge pipework and tundish arrangement.
Can I keep some of my existing radiators?
Often yes — if they're the right size for the room. We assess each radiator on the survey and only recommend a swap if the existing unit is undersized, damaged or a poor match for a rebalanced system.
Do you fit smart thermostats?
Yes — Google Nest, Hive, Tado and Honeywell Evohome are all fitted and paired to the boiler as part of a new install or as a controls upgrade to an existing system.
What's the difference between a system and a combi boiler for central heating?
Combi does heating and instantaneous hot water in one appliance — best for smaller homes. System boiler pairs with an unvented cylinder to deliver mains-pressure hot water to multiple outlets at once — best for 2+ bathroom properties.
Do I need a powerflush?
Any time an old system is retained and a new boiler is fitted, yes. Manufacturer warranties are conditional on system cleanliness, and a magnetic filter alone is not enough to catch decades of magnetite already sitting in the pipework.
Can you handle the electrical work for the controls?
Yes — control wiring for programmers, motorised valves, cylinder stats and room stats is part of the install. Any consumer-unit work is coordinated with a qualified electrician.
Will you help me claim any grant funding?
Where a job qualifies for grant funding (varies by scheme and eligibility) we can help you understand the paperwork requirements. We do not directly administer grant schemes.
Which areas do you cover for central heating?
Greater London and the surrounding Home Counties — Kent, Surrey, Essex, Hertfordshire, Buckinghamshire, Berkshire, Bedfordshire, Middlesex and West Sussex.
Fixed price. Gas Safe.
12-month guarantee.
Free estimates from Ian directly — no call centre, no subcontractors, no surprise bills. One point of contact from first call to twelve-month follow-up.