Most establishments and buildings in the UK rely on commercial boilers, which typically last for more than a decade with proper care. Because a boiler malfunction can result in property damage and even health hazards, it’s a legal requirement to get your commercial boiler inspected annually by commercial boiler engineers.

However, regular boiler servicing and maintenance is also a must. Beyond the comprehensive annual inspection, business owners and commercial landlords should check their boilers frequently. This allows for the prevention as well as early detection of issues, which might lead to your boiler breaking down if neglected.

Regular maintenance of your commercial boiler will maximise its lifespan, and your business operations can continue running smoothly.

Commercial Boiler Preventative Maintenance Checklist

An essential practice for commercial boilers is having a daily log of major settings, such as operating temperature, flue gas temperature, and water levels as well as information about any issues your boiler might be having. This is especially important if more than one person is in charge of monitoring the commercial boiler.

Alongside a daily log, you can consult the commercial boiler preventative maintenance checklist below, which describes what you need to do daily, weekly, monthly, quarterly, and annually:


  • Check if the boiler temperature and pressure and exhaust temperature are within range
  • Pay attention to any unusual noises or vibrations
  • Look around and under your boiler for any leaks of water, flue gas, or fuel
  • Keep the area around the boiler free from obstructions such as debris or snow
  • Examine the burner flame through the boiler’s sight port to see if there’s any sooting or signs of damage
  • Blowdown the bottom of the boiler, then the water column through the column drain valves to remove excessive water
  • Make sure if the stack temperature is between 50 to 100 degrees to confirm proper flue gas exiting
  • Note any error or service codes on the display panel and report these to a technician immediately
  • Inspect the piping and components quickly for any blockages


  • Look at the signal strength of both the pilot and main flame
  • Check if the de-alkaliser, water softener, and chemical feed system have the proper level of chemicals and salts
  • Examine the fuel safety valves in the main burner for leakage and operating issues
  • Inspect and clean compressor air filters, air swirlers, and ignition electrodes
  • Test if the operating and safety controls are turning on and off properly while noting the pressure gauge
  • Do an evaporation test for low water levels, at which the burner should stop and alarms should sound
  • Go through alarms and signal lights to make sure they’re functioning as expected


  • Test the boiler safety relief valves based on the manufacturer’s instructions and your inspector’s recommendations
  • Get a water treatment test done to minimise impurities that could potentially build up in your boiler
  • Remove any debris or dust in the filter access panel and clean or replace the air filter as needed
  • Thoroughly examine the safety relief valve and relief valve discharge pipes for weeping or leaks
  • Check the combustion air piping and flue gas vent piping for signs of deterioration, then clean out any blockages
  • Look out for condensate, which appears white and powdery, in the piping because this produces safety issues such as corrosion
  • Inspect the fan, air pressure, and high pressure or temperature interlocks
  • Observe the outside of your boiler for any hotspots, which show overheated areas


  • Look at the boiler hydronic piping for leakages
  • Observe the burner flame’s appearance, which should look blue to indicate proper and complete combustion
  • To make sure your boiler works all winter and fit proper insulation on the pipes to avoid bursting because of frozen water inside
  • Inspect electric wirings and switches for any loose connections or signs of overheating
  • Check the combustion control system and reset it with a combustion analyser that reads oxygen, carbon monoxide, and nitrogen oxide levels
  • Ensure that base-mounted pumps have correct alignment
  • Examine the gaskets on the waterside and fireside and replace if necessary for leak prevention
  • Replace or clean and reinstall the plugs in the control pipes


Every year, you’re required to have your boiler go through a comprehensive inspection, where every component will be examined. This will involve the following tasks:

  • Perform leak testing on all fuel valves
  • Go through all control settings, including those for test safety and operations
  • Check the gas and safety valves based on manufacturer recommendations
  • Look out for signs of degradation in insulating materials
  • Search for oxygen corrosion in all valves and piping
  • Clean the burner assembly, igniter, and flame sensors as well as the boiler furnace
  • Remove sediments inside the boiler by opening manholes and hand holes and flushing it with water
  • Make sure the heating system is working fine and water pH levels are correctly maintained

Each commercial boiler comes with a unique set of instructions based on the manufacturer, so read the instruction manual as well and keep it close at hand. Once you detect any problems, report it to a commercial boiler engineer immediately. By practising regular maintenance of your commercial boiler, it will remain in good working order for years to come.

Get in touch with us at Invictus Mechanical today to see how our expert engineers can help to maintain and inspect your commercial boiler.