Boiler warranties and workmanship guarantees
Manufacturer warranties on new boilers commonly run 5-10 years, but usually require annual servicing by a registered engineer to stay valid — check whether it has to be the same installer or any Gas Safe engineer. This is separate from any workmanship guarantee the engineer offers on their own installation work.
What affects the cost
Cost depends on the type of system (combi vs system vs conventional), whether it's a straightforward swap or a full system change, boiler brand and output size, and property access. Moving a boiler's location, rather than replacing it in place, adds cost because of the extra pipework, flue routing and making good involved.
Understanding the labour vs materials split
The boiler itself is often the largest single cost, but labour, flue work, and any additional pipework or radiator changes add up. If a quote looks cheap, check it specifies the same boiler tier (entry-level vs mid-range) as a competing quote, not just a lower labour charge.
Electric boilers, pros and cons
Electric boilers avoid combustion entirely (no flue, no CO risk, no Gas Safe requirement) but electricity typically costs more per unit than gas, so running costs can be higher for the same heat output. They suit smaller properties or as a backup rather than being the default choice for most UK homes.
Why Gas Safe registration is a legal requirement
Anyone installing, servicing or repairing a gas appliance or gas pipework in the UK must by law be on the Gas Safe Register, which replaced CORGI in 2009. This covers boilers, gas fires and gas cookers. Using an unregistered engineer for gas work isn't just risky, it's illegal, and any resulting certificate isn't valid.
Smart thermostats and heating controls
A smart thermostat can improve control and, for some households, cut heating costs by learning usage patterns and allowing remote control — but it needs to be compatible with your specific boiler and wiring (some older systems need an additional wiring centre). Worth confirming compatibility before buying one separately from your engineer.
When to replace vs keep existing radiators
Radiators themselves rarely need replacing unless damaged, corroded, or you're changing the property's heat demand (e.g. adding a heat pump, which often needs larger radiators to run at a lower temperature). A power flush can often extend a radiator's working life significantly cheaper than replacement.
Three steps to hiring the right heating engineer
First, confirm Gas Safe registration and ask to see the ID card, which lists exactly what gas work they're qualified for. Second, get a written quote naming the boiler model. Third, ask what the manufacturer's warranty requires (usually an annual service) to keep it valid.