Central Heating Installation

What does a full central heating installation involve?

A full installation means designing and fitting the complete wet system: heat-loss calculation and system design, boiler, flow and return pipework, radiators and TRVs in every room — or underfloor heating where it suits — zone valves, wiring and controls, then a BS 7593 cleanse, inhibitor dose, magnetic filter and full balancing at commissioning.

The sequence runs design first, disruption second, commissioning last. The design visit produces the radiator schedule and pipe layout; then the pipework goes in, radiators are hung, the boiler is installed and the controls wired. First-fix pipework in an occupied house is the disruptive stretch, and we plan it room by room so you're never camping in your own home.

Commissioning is where cheap installations are exposed years later. We flush the system to BS 7593 so no flux, swarf or jointing debris is left circulating, dose it with inhibitor, prove every zone and TRV, and balance the radiators so the farthest one heats as well as the nearest — then set up and demonstrate the controls.

How are radiators sized correctly?

Radiators are sized from a room-by-room heat-loss calculation: the room's dimensions, external wall area and construction, glazing type and area, floor and ceiling losses and air changes are computed into a watt figure, and the radiator is chosen to meet it at the system's design flow temperature.

A radiator's quoted output assumes water far hotter than a condensing boiler should run — at the lower flow temperatures where condensing boilers hit their best efficiency, the same radiator gives out a third less heat. Correct modern practice sizes radiators for low-temperature operation, which often means slightly larger panels than the old rule of thumb — and in return the boiler condenses properly all winter and the gas bill shows it.

Guesswork sizing fails in exactly the houses we work in most: the solid-walled Victorian terraces of Surbiton, Kingston and Thames Ditton, where the "always cold" front room is nearly always an undersized radiator, not a boiler fault. The calculation takes an hour and governs twenty-five years; we've never regretted doing it.

Which smart thermostat is best: Hive, Nest or tado?

All three are good, and the right one depends on your household. Hive is the simplest to live with and suits people who want schedules that just work. Nest learns your patterns and suits set-and-forget households. tado offers the finest control — per-room smart TRVs and strong weather compensation — and suits zoned systems best.

The honest detail beneath the brochures: Hive's app and scheduling are the most straightforward, and its heating-plus-hot-water version suits system boilers with cylinders. Nest's auto-schedule genuinely works if your week is regular, and is more frustrating if it isn't. tado is the enthusiast's choice — its smart radiator thermostats give true room-by-room control on top of zoning, and its weather and load compensation can modulate compatible boilers directly, which squeezes out real efficiency rather than app-deep cleverness. On a new combi installation, a smart control with automation and optimisation is also one of the routes to Boiler Plus compliance. We fit and configure all three brands and will tell you plainly which fits your house; we hold no stock that needs shifting.

What does full central heating cost in 2026?

A complete central heating installation — boiler, radiators, pipework, controls — typically costs £5,500–£9,500 in 2026 for a three-bed house, depending on radiator count, pipework complexity and boiler choice. Extending an existing system into an extension usually runs £1,200–£2,500; a full radiator-and-pipework replacement without the boiler, £3,500–£6,500.

What moves the number is mostly labour and access, not metal: suspended timber floors cost less to pipe than solid floors that need channelling, and a straightforward semi costs less than a Victorian terrace where every run negotiates original joists. The choice of new boiler swings the total too, and we'll price the options side by side.

Our quotes are fixed and itemised: design, boiler, every radiator by room, controls, the BS 7593 cleanse, inhibitor and magnetic filter (standard, not extras), labour and VAT, with building control notification for the gas work included — on a project of this size, a written specification is how both sides stay friends.

Why do a BS 7593 cleanse, inhibitor and magnetic filter come as standard?

Because system water quality decides how long the whole installation lasts. BS 7593 is the British Standard for treating water in heating systems: cleanse the system at commissioning, dose it with corrosion inhibitor, maintain that protection over its life. Skipping it shortens boiler and radiator life and can jeopardise guarantee claims.

The chemistry is unglamorous and relentless: a new system contains flux and swarf, an old one years of black magnetite sludge, and left in place the debris settles in the heat exchanger and radiator bottoms — the classic cold-at-the-bottom radiator is sludge, not age — exactly what a power flush clears. Inhibitor stops the corrosion that manufactures the sludge; the magnetic filter catches what still forms.

Surrey sharpens all of this. At over 300 ppm, our water adds limescale to the corrosion story, and manufacturers' guarantee terms lean on BS 7593 compliance — scale and sludge damage are among the commonest grounds for refused claims. This is why cleanse, inhibitor and filter sit in our standard specification rather than the options list — we'd rather lose the odd quote than fit systems designed to fail slowly.