You should service a domestic boiler once a year as a rule of thumb, ideally every 12 months rather than letting it drift to 18 months or more.

Quick Scoop

Most manufacturers, heating engineers, and safety bodies recommend an annual boiler service for both gas and oil boilers. This helps keep it efficient, safe, and within warranty, and can be a legal or insurance requirement in some situations.

How often to service your boiler

  • Gas boilers: Every 12 months, by a qualified gas engineer.
  • Oil boilers: Every 12 months, by an oil-qualified technician.
  • Electric boilers: Not always mandatory yearly, but strongly recommended annually to extend lifespan and catch faults early.
  • Landlords / rental properties: Annual servicing is typically required by law or by safety regulations and insurance.

A common pattern is to book the service once a year in summer or early autumn so everything is ready before heavy winter use.

Why an annual service matters

  • Safety: Checks for gas leaks, combustion issues, and carbon monoxide risks, which can be fatal if unnoticed.
  • Reliability: Technicians can spot worn parts and fix small issues before they become winter breakdowns.
  • Efficiency and bills: A clean, properly tuned boiler burns fuel more efficiently, helping keep energy bills lower.
  • Warranty and insurance: Many boiler warranties and some insurance policies require proof of annual servicing to stay valid.
  • Lifespan: Regular servicing helps boilers reach their typical 15–20 year life rather than failing early.

A heating company guide notes that “oil and gas boilers alike should be serviced every year,” and warns that longer gaps can be “at best, not ideal.”

Signs you shouldn’t wait

Even if you’ve had a recent service, call an engineer sooner (don’t wait for the annual date) if you notice, for example:

  • Unusual noises (banging, whistling, gurgling) from the boiler or pipes.
  • Pilot light or flame burning yellow/orange instead of a clear blue on gas boilers.
  • Frequent pressure drops or error codes.
  • Soot, scorch marks, or strange smells around the boiler.
  • Radiators taking much longer to heat or hot water running lukewarm.

These can indicate combustion problems, leaks, or internal faults that need a professional to check.

What happens in a typical service

A standard domestic boiler service usually includes checks such as:

  • Inspecting for gas or oil leaks and checking connections.
  • Checking burner operation, flame, and gas pressure.
  • Cleaning internal components where required.
  • Checking flue and ventilation for safe exhaust of fumes.
  • Verifying system startup, controls, and safety devices.

A homeowner forum user sums up the attitude many experienced owners take: they get the boiler checked every year, even if it “just seems like an hour of fiddling,” because “carbon monoxide kills.”

TL;DR: For almost all homes, aim to service your boiler every 12 months, preferably before winter, and never ignore safety warning signs or unusual behavior in between services.

Information gathered from public forums or data available on the internet and portrayed here.