Oil-fired boilers, what's different
Oil boilers are common in properties off the mains gas network, need an oil storage tank with its own maintenance and safety considerations, and are serviced by OFTEC-registered engineers rather than Gas Safe (which only covers gas). If you're off-grid, confirm your engineer's OFTEC registration specifically.
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.
How long does heating work take?
A straightforward like-for-like boiler swap is usually a one-day job. Moving the boiler's location, or a full system replacement including radiators, commonly takes 2-4 days. An annual service is typically under an hour.
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.
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.
Boiler cover and service plans
Separate from a manufacturer's warranty, some homeowners take out an annual boiler cover plan (often through an energy supplier) that includes servicing and breakdown cover. Worth checking what's already included in a recent warranty before paying for overlapping cover.
How heating engineer quotes work
Describe the current system (boiler type and age, number of radiators, any known faults) and heating engineers can give an initial estimate; the firm price usually follows a site visit, since pipework condition and access aren't always obvious from a description alone.
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.