Background checks and identity verification
Every Gas Safe registered engineer has an ID card with their registration number and the specific categories of gas work they're licensed for — ask to see it, and you can also check a registration number directly on the Gas Safe Register website before booking.
Carbon monoxide safety
A carbon monoxide alarm should be fitted near any gas appliance, and tested regularly like a smoke alarm. Signs of a potential CO issue include a yellow/orange (rather than blue) gas flame, soot marks around an appliance, or unexplained headaches/nausea that ease when you leave the property — treat these as urgent.
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.
Combi vs system vs conventional boilers
A combi heats water on demand with no tank or cylinder, suits smaller properties with one bathroom. A system boiler uses a hot water cylinder but no cold water tank, better where several taps might run at once. A conventional (regular) boiler uses both a tank and cylinder, common in older or larger properties, or where mains pressure is poor.
Frozen condensate pipes in winter
A frozen condensate pipe (the small plastic pipe draining from a condensing boiler, often outside) is one of the most common winter boiler breakdowns — it causes the boiler to shut down as a safety measure. Pouring warm (not boiling) water over the pipe to thaw it, if safely accessible, sometimes fixes this without a call-out.
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.
Boiler pressure, explained
Most combi boilers run best between 1 and 1.5 bar. Below about 0.5 bar the boiler will usually stop working or show a fault; above 2.5-3 bar the pressure relief valve may discharge water. Many systems have a filling loop that lets you safely top up pressure yourself — worth asking your engineer to show you how during a service.
Common heating engineer jobs
Heating engineers install, service and repair boilers and central heating systems: annual boiler services, fault diagnosis, radiator installation and balancing, powerflushing, and full system replacements. Many also work on unvented hot water cylinders and, increasingly, heat pumps and other low-carbon heating.