Gas Boiler Commissioning Checklist_ What Every UK Homeowner Should Know Before Signing Off

1. Gas Boiler Commissioning Checklist: What Every UK Homeowner Should Know Before Signing Off At Plumr, we often get asked what actually happens during a boiler installation—and more importantly, what ensures that it’s safe, efficient, and fully compliant. That’s where the gas boiler commissioning checklist comes in. For homeowners across the UK, understanding this process is essential for peace of mind, energy efficiency, and compliance with Gas Safe regulations. In this blog, we’ll walk you through everything you need to know about this checklist—from what’s included, to why it matters, and how it protects your home and investment. Whether you're replacing an old system or installing a brand-new boiler, this is your guide to ensuring everything is done by the book. What Is Boiler Commissioning?

2. Boiler commissioning is the final and arguably most important stage of the installation process. It’s the part where your engineer ensures your new gas boiler is working safely, efficiently, and in line with the manufacturer’s specifications. The gas boiler commissioning checklist acts as a standardised guide to ensure nothing is missed. Without proper commissioning, your boiler might not operate at its best—or worse, it could pose a safety risk. At Plumr, we treat commissioning as a non-negotiable step that safeguards your home and guarantees your warranty. Why Does the Gas Boiler Commissioning Checklist Matter? Here in the UK, we’re required to follow strict Gas Safe and Building Regulation standards. The checklist ensures that the boiler installation: ● Meets legal and safety requirements ● Operates at optimal efficiency ● Won’t void your manufacturer’s warranty ● Reduces the risk of carbon monoxide leaks ● Is properly documented for future service and resale value A properly commissioned boiler will also save you money over time by running more efficiently and lasting longer. It’s not just a tick-box exercise—it’s a guarantee of quality and safety. What’s Included in the Gas Boiler Commissioning Checklist? Here’s a breakdown of what a qualified engineer, like those at Plumr, will check and record during the commissioning stage: ? Installation Verification First, the engineer will ensure the boiler has been correctly installed according to both manufacturer instructions and Gas Safe guidelines. This includes:

3. ● Confirming correct location and secure mounting ● Inspecting pipework for tightness and alignment ● Checking flue positioning and terminal clearance ? Gas Supply and Pressure Check The engineer will test the gas inlet working pressure and ensure the boiler is receiving the correct gas flow. If there’s a mismatch, it could affect combustion and overall efficiency. ? Safety Devices and Controls Testing ● Pressure relief valve ● Overheat thermostat ● Safety lockouts and reset functions ● Flame sensing device All of these will be tested to ensure the boiler shuts down safely if there’s an issue. ? Flue Gas Analysis Using a flue gas analyser, your engineer will check combustion levels, particularly carbon monoxide (CO) and carbon dioxide (CO₂) output. These results must fall within a specified range, and if not, adjustments will be made to burner settings. ? System Filling and Bleeding Your system will be filled with water and any trapped air will be removed from radiators and pipework. The pressure is checked, and the heating is switched on to ensure full circulation. ? Benchmark Logbook Completion Every new boiler comes with a Benchmark Commissioning Checklist—a document that must be filled in and signed by your engineer. It’s proof that the boiler has been installed and tested correctly. Without this, your warranty could be invalid. At Plumr, we ensure this checklist is completed, signed, and handed over to you before we consider the job done. What Should You Expect as the Homeowner?

4. As the customer, you should expect more than just the boiler turning on. After completing the gas boiler commissioning checklist, your engineer should: ● Explain how to use your new thermostat or programmer ● Show you how to top up pressure if it drops ● Provide you with the completed Benchmark logbook ● Offer advice on registering your warranty We believe in full transparency at Plumr—so you’ll never be left in the dark about how your heating system works. Common Mistakes to Avoid Sadly, not all companies follow best practices. Here are a few red flags to watch out for during or after your boiler installation: ● Your installer rushes through the job without showing you how anything works ● You don’t receive a signed Benchmark checklist ● The installer doesn’t test the boiler while you’re home ● No flue gas analysis is carried out Avoid these risks by choosing trusted professionals—like our Gas Safe registered engineers at Plumr—who follow the full commissioning process every time. Consequences of Skipping Commissioning Skipping the commissioning step or doing it improperly can have serious implications: ? Safety Hazards Incorrect combustion settings can result in dangerous carbon monoxide emissions. ? Financial Loss An uncommissioned boiler is often not covered by warranty. You’ll be on the hook for repairs or replacement.

5. ? Reduced Efficiency Your energy bills could be higher than necessary, and the system might not heat your home properly. ? Legal Issues If you ever sell your home, missing documentation (like the Benchmark log) could delay the process. When you choose Plumr, you can rest assured we’ll provide all required documentation, including registration with Gas Safe and certification under Building Regulations. Tips to Ensure a Smooth Boiler Commissioning Process As a homeowner, you can play a role in making sure commissioning goes smoothly: 1. Hire a reputable installer. Always ask for a Gas Safe number and check it online. 2. Ask questions. Don't be afraid to ask what will be checked or how long it will take. 3. Be present. If possible, stay at home during commissioning so you can see the results firsthand. 4. Get everything in writing. Make sure the Benchmark log is fully completed and signed before the engineer leaves. At Plumr, we actively encourage our customers to be part of the process. Your understanding and involvement mean fewer problems down the line. What Comes After Commissioning? Once your boiler is up and running, the job isn’t quite over. Here’s what should happen next: ? Register Your Warranty Manufacturers often require you to register the boiler within 30 days. This can usually be done online or by your installer. ? Schedule Annual Servicing

6. Commissioning is just the start. Keeping your boiler in top condition requires annual maintenance. At Plumr, we offer servicing plans to help you keep on top of this. ? Keep Documentation Safe File your Benchmark checklist and warranty certificate somewhere safe. You’ll need these if you sell your home or make a warranty claim. Final Thoughts The gas boiler commissioning checklist is more than just paperwork—it's your assurance that your new boiler is safe, efficient, and legally compliant. Skipping it or cutting corners can cost you time, money, and peace of mind. That’s why at Plumr, we don’t treat commissioning as an afterthought. It’s an essential part of every boiler installation we do, and we’re proud to offer a service that’s transparent, thorough, and trusted across the UK. If you’re planning to upgrade your boiler or have questions about commissioning, don’t hesitate to contact Plumr. Our friendly team is always here to help—from first consultation to final sign-off.