In short
It depends on the appliance, the pipework and the gas use, not only the building. Gas Safe Register says domestic work covers appliances designed for homes and pipework up to 35mm in a home. Commercial catering equipment, commercial boilers and larger pipework need non-domestic qualifications, which are listed on the back of the engineer's Gas Safe ID card.
How Gas Safe Register separates domestic and commercial work
Every Gas Safe registered engineer holds core qualifications, then adds categories for the work they do. The back of their Gas Safe ID card lists those categories in two groups: domestic and non-domestic. Gas Safe Register's definitions are:
- Domestic work relates to gas appliances designed for use in a home, and gas pipework up to 35mm in diameter in a home.
- Commercial (non-domestic) work categories depend on pipework size, appliance type and gas consumption as well as the type of property.
The building alone does not decide it. Gas Safe Register gives the example of a domestic boiler installed in a church: it can still be treated as a domestic appliance. Equally, a large house with non-domestic appliances or bigger pipework may need an engineer with non-domestic categories.
Typical examples
| Job | Usually needs |
|---|---|
| Wall-hung domestic combi boiler in a home | Domestic categories |
| Domestic-type boiler in a small shop or office | Often domestic categories, depending on the appliance and pipework |
| Restaurant, pub or takeaway kitchen equipment | Non-domestic commercial catering categories |
| Floor-standing or cascade commercial boilers, plant rooms | Non-domestic heating categories |
| Pipework over 35mm or a larger installation | Non-domestic pipework and testing categories |
If you are not sure, tell the engineer the make and model of the appliance and roughly how big the installation is before they visit. A qualified engineer should be able to say which categories the job needs.
The business owner's duty
Regulation 35 of the Gas Safety (Installation and Use) Regulations 1998 makes employers and the self-employed responsible for keeping gas appliances, flues, pipework and safety devices at their workplace in a safe condition. HSE's guidance for employers says work on gas fittings in places such as shops, restaurants, schools and hospitals must be done by a Gas Safe registered engineer who is qualified for that work, and that it is the employer's responsibility to check this. You can check on the Gas Safe Register website or by calling 0800 408 5500.
Work that is normally commercial
- Annual gas safety inspections of catering kitchens, usually recorded on a CP42. See our guide to commercial gas safety inspections.
- Gas interlocks on kitchen extraction to BS 6173. See commercial kitchen gas interlocks.
- Tightness testing and purging of larger installations to IGEM standards. See gas tightness testing.
- Commercial boilers, cascades and plant rooms. See our plant room maintenance checklist.
What to send when you ask for a commercial quote
- The site address and the type of premises.
- Natural gas or LPG.
- A list of gas appliances, with makes and models if you have them.
- Any previous inspection records, interlock details or fault codes.
- Access arrangements and times the site can be worked on.
CombiCert's domestic and commercial work
CombiCert Ltd (Gas Safe 621146) is commercially qualified, and our registration includes commercial catering. We work on homes, shops, offices and cafés, commercial kitchens, commercial boilers and plant rooms, on natural gas and LPG. Commercial clients have included Aston Villa FC, KFC, Burger King and hotel chains. See light commercial gas services, commercial gas and plant rooms and commercial kitchen gas safety.
CombiCert in Telford
CombiCert Ltd is a Gas Safe registered (621146) gas and heating company based at The Old School House, Park Lane, Telford TF3 4TG, working across Telford and Shropshire for homes and businesses. We are open Monday to Saturday, 08:00 to 19:45 (closed Sunday).
Commercial gas work is priced by quote, subject to a site inspection.
See Light commercial gas services for details, or call or WhatsApp 07393 220694, or email hello@combicert.co.uk.
Sources
Frequently asked questions
Can a domestic gas engineer work on a commercial boiler?
Only if they hold the right non-domestic categories. Gas Safe Register says commercial work depends on pipework size, appliance type and gas consumption, and an engineer must be qualified for the specific work. Check the non-domestic section on the back of their Gas Safe ID card, or check their licence number on the Gas Safe Register website.
Is a boiler in a shop or office commercial gas work?
Not always. Gas Safe Register says the property type is not the only test: a domestic-type boiler in a non-domestic building can still be domestic work, while larger appliances and pipework over 35mm need non-domestic categories. Give the engineer the boiler make and model and they can tell you which qualifications the job needs.
Who checks that a commercial gas engineer is qualified?
The business does. HSE says employers must make sure gas work in places such as shops, restaurants, schools and hospitals is done by a Gas Safe registered engineer qualified for that work, and that checking this is the employer's responsibility. Use the Gas Safe Register website or call 0800 408 5500 to check an engineer.
What commercial gas work does CombiCert do?
CombiCert is commercially qualified and its Gas Safe registration (621146) includes commercial catering. Our commercial work includes CP42 kitchen inspections, gas interlocks, tightness testing and purging, commercial boilers, plant rooms and LPG. Commercial clients have included Aston Villa FC, KFC, Burger King and hotel chains. Commercial work is priced by quote.
Does CombiCert cover commercial gas work outside Telford?
Yes. CombiCert's commercial work covers Telford, Shropshire, the West Midlands and further afield when the job justifies it, and we install packaged plant rooms UK-wide. Commercial work is priced by quote, subject to a site inspection. Call 07393 220694 with the site address, the equipment and what you need doing.
This guide is general information, not a substitute for an on-site assessment by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.