How to Build Your ACS Portfolio:
The Photo & Evidence Guide

What Is the ACS Portfolio?

Before you can sit your ACS assessments and get Gas Safe registered, you need to complete a portfolio of supervised gas work — typically 30–40 jobs, with evidence of around 150 hours of supervised work being common, though the exact requirement depends on your training provider. Every job needs to be documented with photos and paperwork, then signed off by your supervising Gas Safe registered engineer.

Your portfolio proves to the assessment centre that you’ve had real, hands-on experience across a range of gas work: installations, servicing, fault-finding, tightness testing, and safety checks.

The quality of your evidence matters. A well-documented portfolio sails through. A messy one with vague photos and missing details gets sent back — costing you time and money.

What Assessors Actually Want to See

Assessment centres are checking three things:

1. You were there and did the work — not just watching. Photos should show your hands on the tools, not your supervisor doing everything.
2. You covered the required competencies — boiler installs, servicing, tightness testing, ventilation checks, combustion analysis, gas rate checks, unsafe situations, etc.
3. The work is traceable — each job must have an address or job reference, date, description of work done, and your supervisor’s signature and Gas Safe number.

The 8 Photo Stages for a Boiler Installation

This is the question that comes up constantly. Here’s the stage-by-stage breakdown:

Video vs Photos: Which Is Better?

Some trainees record the whole job on video and extract stills later. Here’s the honest comparison:

Recommendation: Take photos at each stage. It takes 5–10 seconds to snap a photo, and the result is clearer and more professional than extracting a still from a shaky video. Video can work as a backup, but don’t rely on it as your primary evidence.

Practical Tips: Don’t Slow the Job Down

The biggest concern trainees have is annoying their supervising engineer by stopping every 5 minutes for photos. Here’s how to manage it:

• Tell your supervisor upfront. “I need to grab a few photos at each stage for my portfolio — I’ll be quick.” Most engineers remember doing this themselves and won’t mind.
• Snap during natural pauses. When the kettle’s on, when you’re waiting for sealant to cure, when your supervisor’s on the phone. Don’t interrupt flow.
• Use burst mode. Take 3–4 shots quickly and pick the best one later. Faster than trying to frame the perfect photo on site.
• Get the close-ups when nobody’s watching. Gauge readings, data badges, and pipework labels don’t need anyone else present — grab them quietly.
• Write notes immediately. Use your phone’s notes app to jot down key details (pressures, gas rate, defects found) right after the job. You will forget by tomorrow.

The Do’s and Don’ts

Do

• Photograph before, during, and after every job. The before shot is the one most people forget.
• Include a tape measure or ruler in clearance photos for scale.
• Capture your analyser screen showing combustion readings — assessors love these.
• Get your supervisor to sign off each job on the day, not three weeks later from memory.
• Include the job address or reference number — write it on your phone notes app alongside each photo set.
• Photograph any unsafe situations you find and document what action you took. These are gold for your portfolio.
• Cover a variety of work: installs, services, breakdowns, safety checks, tightness tests, meter work.
• Back up your photos to the cloud. One dead phone = months of lost evidence.

Don’t

• Take photos of the customer’s face, personal belongings, or anything identifying without their permission.
• Submit blurry, dark, or unidentifiable photos. If you can’t tell what’s in the photo, neither can the assessor.
• Leave your write-up until the end. Documenting 30 jobs from memory the night before assessment is a nightmare.
• Photograph only the finished result. The process matters as much as the outcome — assessors want to see the journey.
• Use someone else’s photos or recycle the same photos across multiple jobs. Assessment centres check.
• Forget to include yourself in at least some photos. The portfolio proves you did the work.

Beyond Installs: Other Work to Document

Your portfolio can’t just be boiler installs. You need a spread across:

• Boiler servicing — combustion analysis, heat exchanger inspection, condensate trap, controls check
• Breakdown / fault-finding — fault codes, parts replaced, before and after
• Landlord gas safety checks (CP12s) — tightness test, appliance checks per the CP12 checklist
• Cooker installs — stability chain/bracket, gas connection, pressure test
• Gas fire servicing — cleaning, spillage test, flue flow
• Tightness testing — dedicated photos of gauge, let-by test, drop test
• Unsafe situations — what you found, classification (At Risk / Immediately Dangerous), warning notice issued, remedial action

Organising Your Evidence

The biggest pain point for trainees isn’t taking photos — it’s organising them afterwards. Dozens of jobs and hundreds of hours generates hundreds of photos and pages of notes. Here’s how to keep on top of it:

1. Create a folder per job on your phone or cloud storage. Name it with the date and address (e.g. “2025-03-15 — 42 Oak Road, boiler install”).
2. Write your job notes the same day. What you did, what you found, pressures and readings, any defects. 5 minutes today saves an hour later.
3. Get supervisor sign-off immediately. Don’t batch 10 jobs and ask for signatures later — your supervisor won’t remember the details.
4. Back everything up. Google Drive, iCloud, or a dedicated tool. If your phone dies, your portfolio dies with it.

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