Commercial Gas Questions Answered
The questions businesses ask most about commercial gas, answered by Gas Safe registered engineers. Each answer links to the page with the full detail.
These questions come from what people actually search for in Google in the UK. Each short answer is followed by a link to the service page that explains it in full. For anything not covered here, our commercial gas engineer London team answers the phone 24 hours a day on 0208 935 5572.
Commercial gas engineers
What is a commercial gas engineer?
A commercial gas engineer is a Gas Safe registered engineer qualified to work on non-domestic gas installations: commercial boilers over 70kW, catering equipment, gas pipework, meters, boosters and plant-room safety controls. They hold non-domestic ACS categories that a domestic-only engineer does not.
Read the full answer →Can a domestic gas engineer work on commercial gas appliances?
No. A domestic gas engineer can only work on commercial installations if they also hold the matching non-domestic Gas Safe categories, such as commercial catering or non-domestic boiler and pipework categories. Check the back of the engineer's Gas Safe ID card before work starts.
Read the full answer →Who is responsible for gas safety in a commercial property?
Under the Gas Safety (Installation and Use) Regulations 1998, whoever controls the gas appliances is responsible: usually the employer or business occupying the premises, or the landlord where the lease makes them responsible for the plant. The lease should state who arranges maintenance and checks.
Read the full answer →Where is the emergency gas shut-off valve in a commercial building?
The main emergency control valve is normally next to the gas meter, where the supply enters the building. Commercial kitchens and plant rooms usually also have a local isolation valve or a red emergency stop button near the exit. If you smell gas, turn it off and call 0800 111 999.
Read the full answer →Commercial boilers
What is a commercial boiler?
A commercial boiler is a gas boiler that heats a non-domestic building, such as an office, school, hotel or residential block. In gas work a boiler is generally treated as commercial when its net heat input is over 70kW, and it must be worked on by an engineer with non-domestic categories.
Read the full answer →When is a gas boiler classed as commercial?
A gas boiler is generally classed as commercial (non-domestic) when its net heat input exceeds 70kW, or when it is installed in non-domestic premises. Several smaller boilers linked in a cascade with a combined output over 70kW are also treated as a commercial installation.
Read the full answer →How does a commercial boiler work?
A commercial boiler burns gas in a sealed combustion chamber and passes the heat through a heat exchanger into water, which pumps circulate around radiators, air handling units or hot water cylinders. Large buildings often run several boilers in a cascade, with controls bringing boilers on and off to match demand.
Read the full answer →How much does a commercial boiler cost to replace?
The cost depends on the heat load, the number of boilers, flue and plant-room alterations, controls, access and whether pipework or pumps also need replacing. We survey the building and give a fixed written quote; call 0208 935 5572 to arrange the survey.
Read the full answer →How do you size a commercial boiler?
A commercial boiler is sized from a heat-loss calculation of the building, plus hot water demand and a margin for warm-up. The total is often split across several modular boilers so the plant can run efficiently at low load and keep heating if one boiler fails.
Read the full answer →Who is responsible for the boiler in a commercial property?
The person or company in control of the boiler is responsible for keeping it safely maintained, which is usually the business occupying the building or the landlord if the lease puts plant maintenance on them. Annual servicing with a written record shows that duty is being met.
Read the full answer →How often should a commercial boiler be replaced?
There is no fixed age. Replacement is usually considered when the heat exchanger is failing, parts are no longer available, breakdowns are becoming frequent or efficiency has fallen well behind modern condensing boilers. A service record showing repeat faults is the best guide.
Read the full answer →Testing and purging
What is a gas tightness test?
A gas tightness test checks that gas pipework and fittings are not leaking. The installation is isolated, pressurised and monitored on a calibrated gauge for a set time; any pressure drop beyond the permitted limit means a leak must be found and fixed. Commercial tests follow IGEM/UP/1 or UP/1A.
Read the full answer →How long is a gas tightness test?
It depends on the installation volume and the gauge used. Small installations may need a few minutes of stabilisation and test time, while large commercial pipework can take much longer because IGEM/UP/1 calculates the test duration from the pipe volume and gauge readable movement.
Read the full answer →What is gas purging?
Gas purging is the controlled removal of one gas from pipework and replacing it with another: purging air out with fuel gas before appliances are lit, or purging fuel gas out with air or nitrogen before pipework is opened. Commercial purging follows IGEM/UP/1 with gas detection throughout.
Read the full answer →How should gas purging be carried out?
Gas purging should be planned: calculate the purge volume and flow rate, vent to a safe external point, keep ignition sources away, monitor with a gas detector until the purge is complete, and record the result. On commercial pipework this follows IGEM/UP/1 and is done by a qualified engineer.
Read the full answer →Gas meters
Is a G10 gas meter commercial?
A G10 meter (also called U16) passes up to around 16 cubic metres of gas an hour, which is beyond a typical home. It is commonly found in small commercial premises such as shops and small kitchens, but whether work counts as commercial depends on the installation and appliances, not the meter alone.
Read the full answer →Is a U16 gas meter commercial?
A U16 meter is larger than a standard domestic U6 meter and is typically fitted to small commercial sites. Pipework downstream of a U16 is usually tested to IGEM/UP/1A, which covers installations up to a set volume and pipe size.
Read the full answer →Where is the emergency gas control valve?
The emergency control valve (ECV) is normally fitted on the inlet to the gas meter where the supply enters the building. It should be easy to reach, clearly labelled and turned off with a quarter turn so the handle sits across the pipe.
Read the full answer →Gas safety
Do you need a gas safety certificate for a commercial property?
There is no single law requiring an annual certificate for every commercial property, but the Gas Safety Regulations require gas appliances at work to be safely maintained. Insurers, landlords and local authorities usually expect a current inspection record, and commercial kitchens normally need a CP42.
Read the full answer →How much is a commercial gas safety certificate?
The cost depends on the number and type of appliances, the amount of pipework to test, and whether the site has catering equipment, boilers or both. Send us the appliance list or call 0208 935 5572 and we will confirm a fixed price before booking.
Read the full answer →Who is responsible for the gas safety certificate in a commercial property?
The person in control of the gas installation, usually the occupying business or the landlord if the lease makes them responsible, must make sure it is safely maintained and inspected. The tenant and landlord should agree in writing who arranges inspections.
Read the full answer →Commercial kitchens
What is a gas interlock system?
A gas interlock links the kitchen gas supply to the extraction or ventilation fans. If the fans are not running, a solenoid valve shuts off or prevents the gas supply, stopping appliances being used without enough ventilation to clear carbon monoxide.
Read the full answer →How does a gas interlock system work?
Airflow or current sensors confirm the extract fan is running. Only then does the control panel open the gas solenoid valve. If the fan stops, the valve closes; most systems also include an emergency stop button and a proving check so gas cannot flow while burner taps are open.
Read the full answer →Is a gas interlock system a legal requirement?
BS 6173 and the related guidance require an interlock where a commercial kitchen relies on mechanical ventilation, and the Gas Safety Regulations require installations to be safe. In practice new and refurbished kitchens need one, and older kitchens without one are recorded as a defect at CP42 inspection.
Read the full answer →Water heaters
How long does a commercial water heater last?
Life depends heavily on water hardness, usage and servicing. Annual servicing, descaling and anode checks extend it; neglect in hard-water areas like much of London shortens it. Repeated leaks or a corroded storage vessel usually mean replacement.
Read the full answer →How do you size a commercial water heater?
Size it from peak hot water demand: how many outlets run at once, for how long, and how fast the store must recover. Storage capacity and burner output (recovery rate) are balanced so the busiest hour, such as a kitchen wash-up or hotel morning peak, never runs cold.
Read the full answer →How much is a commercial water heater?
The price depends on storage capacity, burner output, flue type and the work needed to remove the old unit and alter pipework. We confirm a fixed written quote after a survey.
Read the full answer →Gas detection
What is a gas detection system?
A gas detection system uses fixed sensors to monitor a plant room or kitchen for natural gas, LPG or carbon monoxide. When a sensor reaches its alarm level, the panel sounds an alarm and can close a gas solenoid valve to shut off the supply automatically.
Read the full answer →What does LEL stand for in gas detection?
LEL means Lower Explosive Limit: the lowest concentration of a gas in air that can ignite. For natural gas it is about 5% by volume. Detectors alarm at a small percentage of the LEL so action is taken long before an explosive mix can form.
Read the full answer →What is gas detection equipment used to monitor?
In commercial gas installations it monitors for leaking natural gas or LPG and for carbon monoxide from poor combustion or blocked flues, typically in boiler rooms, commercial kitchens and areas with gas pipework.
Read the full answer →How much does gas leak detection cost?
It depends on the size of the installation and how quickly the leak can be traced. The engineer first carries out a tightness test to confirm a leak, then locates it with an electronic detector and leak detection fluid, and quotes for the repair before carrying it out.
Read the full answer →Need a commercial gas engineer in London?
Gas Safe registered commercial engineers, 24 hours a day. Call now or book online and we'll confirm a time.