Commercial gas

Your duties as a business

The Gas Safety (Installation and Use) Regulations apply to non-domestic premises as well as domestic, and the Health and Safety at Work etc. Act imposes broader duties on employers in respect of the safety of people at work and those affected by the work.

In practical terms an employer or person in control of commercial premises must ensure that:

• Gas appliances, pipework and flues are maintained in a safe condition.
• Work on them is carried out only by persons competent for the type of appliance and premises in question.
• Ventilation provision is adequate for the appliances installed and is not obstructed.
• Safety devices, including any ventilation interlock, function correctly.
• Records exist to demonstrate that all of the above is happening.

There is no single ‘commercial CP12’ in the way there is a residential landlord certificate. What matters is a documented regime of inspection and maintenance appropriate to the appliances and the premises, with records that stand up.

Where commercial competence differs

Domestic qualification does not cover commercial appliances. The competence categories are separate and specific, and they cover different appliance types – commercial boilers and plant, commercial catering appliances, laundry equipment, warm air and radiant heating, and commercial pipework sizes.

This matters practically because a domestic-qualified engineer working on a commercial appliance is working outside their competence, and the work is therefore neither compliant nor insured. It is a reasonable and important question to ask any contractor, and the answer should be specific about appliance categories rather than general.

What we do

• Commercial boiler and plant servicing, scheduled around operating hours – see commercial heating and plant rooms.
• Gas safety inspections across all appliances in the premises, with records suitable for insurers and auditors.
• Commercial pipework – new runs, alterations, upsizing and replacement, correctly sized for combined demand.
• Tightness testing and purging on commercial installations.
• Ventilation assessment, covering both combustion air and the interaction with mechanical extraction.
• Gas interlock systems for catering environments, installed, tested and certificated.
• Emergency control valve and isolation work, including making sure isolation is where people can actually reach it.
• Plant decommissioning where appliances are removed from service.

Pipe sizing on commercial installations

The same principle as domestic and with much greater consequence. Every appliance needs a specified gas rate at a specified pressure, the pressure drop from the meter must stay within limits, and the calculation has to account for every appliance running simultaneously.

Commercial installations go wrong for specific recurring reasons:

1. Appliances added over the years without recalculating the whole installation. Each addition seemed small; cumulatively the pipe is undersized.
2. Long runs in large buildings, where the pressure drop over distance dominates.
3. Kitchen extensions – a new range or fryer added to an existing supply that was at its limit.
4. Meter capacity, which is a separate constraint from pipe capacity and requires the gas transporter’s involvement to change.
5. Diversity assumptions that were reasonable and are no longer true.

The symptom is appliances that underperform under load, burners that will not maintain output when everything is running, and lockouts at peak. The diagnosis is a pressure test under full load, which is straightforward and rarely done.

Ventilation, which is assessed as a whole

Commercial premises combine gas appliances with substantial mechanical extraction, and the two interact. A powerful extraction system can depressurise a space sufficiently to affect a flued appliance – in the worst case drawing combustion products back down a flue into an occupied room.

This is why ventilation is assessed across the premises rather than appliance by appliance, and why a change that appears unrelated to gas – a new extraction system, a blocked air path, a sealed-up louvre, a partition – can create a gas safety problem. Any significant alteration to a building containing gas appliances is worth reviewing for this reason.

In catering environments the interaction is formalised through the gas interlock, which physically prevents gas being available unless extraction is proven to be running.