A commercial boiler service is a planned inspection, clean and test of a boiler and the parts that keep it running safely: the burner, flue, controls and safety devices. It is carried out by an engineer qualified for commercial work on that type of boiler, and it usually ends with a written record of what was checked and what was found.
This guide explains what a commercial boiler service usually involves, who can carry one out, how often it is typically done and why the cost varies from one site to the next. It is written for facilities managers, building managers and anyone responsible for heating in a non-domestic building.
What is a commercial boiler service?
Commercial boilers do the same basic job as a home boiler, but at a larger scale and usually as part of a bigger system. A building may have several boilers linked together, a plant room with pumps, pressurisation units and controls, and a building management system (BMS) on top. Commercial boiler servicing focuses on the boilers themselves, but the engineer also looks at how they connect to that wider system.
A service has three aims: to confirm the boiler is safe to use, to keep it running efficiently, and to pick up wear or faults early, before they turn into a breakdown. Many of the faults behind commercial boiler breakdowns in winter are the kind of problems a service is designed to catch.
What does a commercial boiler service involve?
The exact steps depend on the make, model and fuel type, and engineers work to the manufacturer's service instructions for each appliance. A typical service on a gas-fired commercial boiler covers:
- Visual inspection. The condition of the casing, seals, pipework and connections, and any signs of leaks, corrosion, overheating or water damage.
- Flue and ventilation. Checking the flue is intact, properly supported and clear, and that the plant room has the ventilation the appliances need.
- Combustion analysis. An electronic flue gas analyser measures how well the burner is burning and checks carbon monoxide levels in the flue gases.
- Burner and heat exchanger. Inspecting and cleaning as needed, and checking the ignition and flame-sensing electrodes.
- Gas pressures and gas rate. Confirming these match the manufacturer's figures and adjusting them if necessary.
- Safety devices and controls. Testing flame supervision, overheat protection, pressure switches, safety valves and emergency shut-off controls to confirm they work as intended.
- Condensate system. On condensing boilers, clearing traps and drains so the boiler does not lock out.
- Associated plant. A check of pumps, pressurisation units and expansion vessels where they affect how the boiler runs. Servicing or repairing that equipment is usually separate work.
- Service report. A record of the checks made, the readings taken, the work completed and any defects found.
Oil-fired boilers have additional routine tasks, such as replacing the burner nozzle and oil filters and removing soot from the heat exchanger. Contractors differ on whether routine consumables like these are included in the service price.
A gas safety inspection, with its own record, is often carried out on the same visit, but it is not automatically part of every service. Whether it is included depends on the scope agreed with the contractor.
If the engineer finds something unsafe, they make the situation safe, which can mean isolating the boiler until it is repaired, and explain what they found and what is needed. Many faults found this way are the same warning signs that a commercial boiler needs repair that can show up between visits.
Who can service a commercial boiler?
For premises such as offices, shops, schools and hospitals, gas work must be carried out by a Gas Safe registered engineer qualified for the relevant appliance and fuel. Different rules apply in certain industrial and agricultural settings, such as factories and quarries, where the work must be done by a competent person, as the HSE's gas safety guidance for employers explains. Gas Safe registration covers specific types of work, so an engineer registered for domestic boilers is not automatically qualified to work on commercial appliances. Each engineer's Gas Safe ID card lists the types of work they are qualified to do, and engineers and businesses can be checked on the register.
LPG appliances need engineers with the relevant LPG qualifications on their Gas Safe registration. Oil-fired boilers are usually serviced by technicians registered with OFTEC, which runs a competent person scheme for oil heating.
How often should a commercial boiler be serviced?
Annual servicing is the usual baseline. Manufacturers' instructions normally set out service intervals, and insurers may set servicing conditions in their policy terms. Boilers that run long hours, serve critical buildings or are getting older are sometimes serviced more often.
In premises covered by the Gas Safety (Installation and Use) Regulations 1998, regulation 35 places a duty on employers to ensure that gas appliances, pipework and flues at a place of work under their control are maintained in a safe condition. HSE guidance links that duty to regular maintenance in line with manufacturers' instructions. Regulation 35 does not apply in the industrial and agricultural settings mentioned above, which are covered by other health and safety law.
Where premises are let, landlords may have further duties, depending on the premises and how they are used. The annual landlord gas safety check, for example, does not apply to appliances used only in non-residential areas, although other maintenance duties can, as the HSE's guidance for landlords explains. Many sites also time their servicing around the heating season, which the pre-winter heating maintenance checklist looks at in more detail.
What affects the cost of a commercial boiler service?
Most contractors price commercial servicing once they have seen the plant or have its details, rather than from a fixed price list. That is because the time and skills needed vary so much from one site to another. The main factors are:
- Number and size of boilers. A single wall-hung boiler in a small office takes far less time than several large floor-standing boilers.
- Linked systems. In cascade or modular set-ups, each boiler is serviced and the engineer also checks how they work together.
- Fuel type. Gas, LPG and oil boilers each involve different tasks and different registrations.
- Access. Rooftop plant rooms, ceiling-mounted units, confined spaces or the need for access equipment all add time.
- Age and condition. Older boilers may need more cleaning and adjustment, and parts can be harder to source.
- Timing. Out-of-hours or weekend working, often needed to avoid disrupting the building, is usually priced differently.
- Site requirements. Inductions, permits to work, escorted access or asbestos information for older buildings. These vary a lot between offices, schools, factories and other types of building.
- Reporting. Some organisations need records in a particular format for compliance, insurance or tender purposes.
What isn't usually included in a commercial boiler service?
Scope varies between contractors. The routine tasks described above form the service itself; items often priced separately include:
- replacement parts, beyond any routine consumables included in the quote, where worn or faulty components are found
- commercial boiler repairs beyond minor adjustments
- gas tightness testing of the wider gas installation pipework
- servicing or repair of the wider heating system, such as pumps, valves, pressurisation units, water treatment or BMS controls
- a gas safety inspection and record, where this is not part of the agreed scope
- flue cleaning beyond routine checks
- out-of-hours attendance, unless agreed in advance.
How can you compare commercial boiler service quotes?
Because commercial quotes are put together in different ways, the headline figures do not always compare like with like. These questions help show what each quote covers:
- Which boilers and associated plant does the price include?
- Which tasks are included, and does the service follow the manufacturer's instructions?
- Which Gas Safe or OFTEC categories do the engineers hold for commercial work?
- Does the price include a service report, and a separate gas safety inspection and record?
- How are faults found during the service handled and priced?
- Are consumables, parts, call-outs or out-of-hours working included?
Quotes also tend to be more accurate when the contractor has the boiler makes, models and quantities, the fuel type, and details of access to the plant room.
Is a maintenance contract better than one-off servicing?
One-off servicing is booked and priced visit by visit. A planned preventative maintenance (PPM) contract sets out a schedule of servicing and inspections for an agreed period, usually at an agreed price, and may include terms for breakdown response and repairs. Many maintenance schedules are based on SFG20, a widely used maintenance specification developed by the Building Engineering Services Association (BESA).
Which suits a building depends on how much plant it has, how critical heating is and how maintenance budgets are set. There is more on how planned maintenance compares with reactive repairs, and on what a commercial maintenance contract should cover, in separate guides.
Frequently asked questions
Not quite. A service involves cleaning, adjusting and testing to keep the boiler running safely and efficiently. A gas safety inspection assesses the safety of the appliances and installation covered by the agreed inspection, and is recorded separately. The two are often carried out on the same visit, but one does not automatically include the other.
Usually a service report setting out the checks made, the readings taken, the work completed and any defects found. Where a gas safety inspection is part of the agreed scope, it has its own record. Formats vary between contractors, and many facilities teams keep these records together as part of their compliance files.
Inspection, testing and adjustment of gas appliances are work for a suitably qualified engineer. Staff can help by reporting warning signs such as unusual noises, repeated lockouts or a carbon monoxide alarm, and by making sure engineers can get into the plant room when they arrive.
LPG is a gas, so the engineer needs Gas Safe registration with the relevant LPG qualifications. Oil-fired boilers fall outside Gas Safe and are usually serviced by OFTEC-registered technicians.
