Moving from domestic to commercial gas

Most commercial gas engineers started out in domestic work. The move is well trodden, and for an engineer who wants bigger plant, a steadier week and a route into building services, it’s often the best step they make.

It isn’t just a bigger boiler, though. Here’s what’s involved.

The qualifications

Commercial gas work has its own ACS assessments, separate from domestic. For someone who already holds CCN1, the domestic core, the usual route is:

• CODNCO1, the changeover from domestic to commercial core gas safety. It covers the areas where commercial work differs: legislation, ventilation and flueing, and setting supply regulators and appliance pressures on larger installations.
• CIGA1, for commissioning, servicing, repairing and breaking down commercial indirect-fired heating appliances.
• ICPN1, for installing commercial pipework.
• TPCP1A, for tightness testing and direct purging of small low-pressure commercial installations.

Training centres usually expect you to have been Gas Safe registered for at least six to 12 months before you start. Courses run from a few days of revision for experienced engineers to a two or three-week package for someone new to commercial work. The assessments are at Level 3, so it’s worth being honest with yourself about your experience before you book.

As with domestic, your ACS certificates last five years before you need reassessment. Commercial catering is a separate route with its own core assessment, so check which one fits the work you want.

What changes on the job

• Bigger plant: cascade boiler systems, plant rooms, boosters, and burners on larger appliances.
• More controls. Most commercial plant runs through a building management system, and you’ll spend as much time on controls as on gas.
• Planned maintenance. A lot of commercial work is PPM across a portfolio of sites, alongside reactive call-outs.
• Different customers. You’ll deal with facilities managers, main contractors and M&E consultants rather than homeowners.

Why it’s worth it

Commercial engineers tend to have more variety, more structured career paths and more options for moving into supervisor, contracts manager or project roles. Building services companies also tend to invest more in training, because the equipment demands it.

The low-carbon shift makes the move better value, not worse. New commercial buildings in England are moving to heat pumps under the Future Buildings Standard from March 2027. An engineer with commercial gas, F-gas and heat pump experience is far more useful than one with gas alone.

How to make the move

• If you’re employed, ask whether your company will fund the changeover. Many building services firms will, often with a training repayment clause. Our piece on what to check when an employer says “we’ll train you” covers what to look for.
• If you’re self-employed, budget for the courses and the reduced earnings while you train.
• Look for a role where you’ll work alongside experienced commercial engineers for your first few months. That’s where the real learning happens.

If you’re a gas engineer thinking about commercial work, talk to us. We’ll tell you which employers will train you, and what they’ll pay while you learn.

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Sources: Worcester Bosch, Commercial ACS Training and Assessment Course; Fife College, Changeover from Core Domestic to Core Commercial Natural Gas Safety (CODNCO1); Able Skills, What is covered in the commercial gas changeover course; BPEC, ACS assessment information; NICEIC, ACS scheme.