A standard combi boiler replacement in Kent costs £2,200–£3,800 in 2026, fitted and commissioned, for a 24–30 kW Worcester Bosch, Vaillant, or Baxi. System boilers are £2,600–£4,400. Full heat-only (conventional) boilers with cylinder swap £3,500–£6,500. These figures are all like-for-like swaps — moving the boiler to a new position adds £400–£900 for extra pipework, flue routing, and a new condensate run.
Yes, absolutely, for any work on gas appliances, gas pipework, or flue systems. Gas Safe registration is a legal requirement — working on gas without it is a criminal offence. Ask for the card at the first visit; the card shows name, photo, unique ID, and the categories of work the engineer is competent in. Verify online at GasSafeRegister.co.uk. A heating engineer who works on oil or LPG systems also needs OFTEC (oil) or Gas Safe LPG categories on their card.
Annually. Every major manufacturer warranty (Worcester, Vaillant, Baxi, Ideal) requires annual service to keep the warranty valid. A standard service in Kent costs £75–£120 for a combi, £90–£150 for a system or conventional boiler, and £130–£200 for oil boilers. Book in autumn — the engineer finds a problem before you need heating, not on the first cold night of November when everyone else is calling the same engineer.
A combi (combination) boiler makes hot water on demand directly from the mains — no hot-water cylinder. A system boiler works with a cylinder to store hot water. Combis are simpler, cheaper, save space, and are best for 1–2 bathroom homes. System boilers handle higher hot-water demand (3+ bathrooms, large families, showers running at the same time). A heat-only/conventional boiler is the older style — cylinder plus cold-water tank in the loft — and is rarely fitted new now.
For the right home, yes. Air-source heat pumps (ASHP) work best in well-insulated homes with larger radiators or underfloor heating. The Boiler Upgrade Scheme (BUS) grant offers £7,500 off an ASHP install, reducing the net cost to £7,000–£12,000 on a typical Kent home. Running costs are 30–50% lower than gas over a year on a well-designed system. But poorly insulated period homes (solid-wall Victorian, single-glazed) often don't get the efficiency gains and are better with gas until insulation catches up. Ask for a heat-loss calculation before committing.
Yes. Heat pumps contain refrigerant; installers handling refrigerant must hold F-Gas certification (under the EU/UK F-Gas Regulations). For ASHP installs claiming the BUS grant, the installer must also be MCS-certified — MCS is the Microgeneration Certification Scheme and is the only way a homeowner accesses the grant. Most good Kent heat-pump installers hold MCS, F-Gas, NICEIC or NAPIT (for the electrical side), and often Gas Safe (for hybrid systems).
Benchmark is the industry's commissioning record, issued at the end of any new boiler install. It records the flow rates, pressures, gas rate, flue analysis, and installer details. Keep it with your home paperwork — every major manufacturer requires a completed Benchmark for warranty claims, and a missing Benchmark is the single most common reason for a declined warranty claim. A proper Kent heating engineer hands it over signed at handover.
Often, but not always. A powerflush circulates cleaning chemicals through the heating system to remove sludge that restricts flow. For an older system (10+ years) with radiators that are cold at the bottom, yes — a powerflush (£400–£700) plus a magnetic filter (£120–£220 fitted) extends the new boiler's life substantially. For a newer system or a recent powerflush, a chemical flush (£120–£220) is usually enough. A Kent engineer who insists on a powerflush for every job is over-quoting; one who insists a 20-year-old radiator system doesn't need one is under-quoting.
Manufacturer warranties range from 5 years (entry-level Baxi, Ideal) to 12 years (Worcester Bosch Greenstar Lifestyle with accredited installer). Vaillant ecoTEC Plus hits 10 years with a Vaillant Advance installer. The warranty is conditional on annual servicing and correct commissioning. Workmanship warranty from the installer is separate, typically 12 months on labour. Always register the boiler with the manufacturer within 30 days; some warranties start at install date, some at registration date.
A proper heating engineer does a heat-loss calculation (often using software like Heat Engineer or Stars) that sizes the boiler to the house's peak demand. A 3-bed Kent semi typically needs a 24–30 kW combi. A 4-bed detached with 2 bathrooms often wants a 30–35 kW combi or a 15–18 kW system boiler plus a 180 L cylinder. An engineer who quotes a boiler size without looking at the radiators and asking about hot-water demand is guessing. Oversized boilers waste gas and short-cycle; undersized boilers run flat-out and fail early.
A TRV (Thermostatic Radiator Valve) sits on the flow side of each radiator and closes automatically when the room reaches a set temperature. Since Building Regulations Part L 2022, TRVs are mandatory on all new or replaced radiators except in the room with the main thermostat. Retrofitting TRVs to an existing system costs £25–£45 per radiator fitted, and they pay back in gas savings within 1–3 years on most Kent homes.
A like-for-like combi swap in a Kent home takes 6–10 hours on site — one day's work. A boiler relocation takes 1.5–2 days. A full heat-only to combi conversion (removing cylinder, tanks, and changing the pipework) takes 2–3 days. Add half a day for a powerflush and magnetic filter fit. Expect hot water and heating back on the same evening of a standard swap.
Yes. Manufacturer warranties are useful within their term but plenty of good local engineers repair Worcester, Vaillant, Baxi, Ideal, Glow-worm etc. after warranty expiry. Parts are generally available for 10–15 years after a boiler goes out of production. For anything older than 15 years, or any boiler that's failed three times in a winter, it's usually cheaper to replace than to keep repairing. Our Kent heating engineer directory lists local firms who cover both servicing and repairs.
If it's a modern (post-2010) insulated foam-lagged cylinder in good condition, probably yes — a new cylinder is £600–£1,100 fitted. If it's a pre-2000 copper cylinder with a loose red jacket, no — it's wasting £80–£150 a year in heat loss. Unvented pressurised cylinders (Megaflo, Santon) typically last 20–25 years; vented open-tank cylinders can last 30+ years. A Benchmark-compliant new cylinder comes with its own warranty and is often required when you upgrade to a system boiler.
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