A gas tightness (soundness) test confirms that a commercial gas installation holds pressure correctly, with no leaks in the pipework or connections. ComGas carries out tightness testing on new, altered and existing commercial installations for businesses across Surrey and surrounding counties.
Tightness testing is a defined procedure, not a general inspection.
A gas tightness test — sometimes called a soundness test — checks that a gas installation holds pressure correctly over a set period, confirming there is no leakage from the pipework, fittings or connections being tested. It is a specific, standalone procedure with its own defined method, distinct from a full gas safety certification visit and from the physical installation of pipework itself.
ComGas carries out tightness testing on new pipework as part of a wider installation project, on existing pipework where a test is required for its own sake, and ahead of purging or appliance commissioning where a new or altered installation needs to be confirmed sound before it goes into service. Testing can be arranged as a standalone visit or combined with related pipework, purging or decommissioning work.
ComGas Services UK Ltd Commercial gas tightness testing from Farnham, Surrey.
Gas tightness testing services
Testing for new, altered and existing commercial gas installations.
We can carry out a tightness test as its own visit, or as part of a wider pipework, purging or installation project.
New & Altered Pipework Testing
Tightness testing carried out on any new or altered gas pipework before it is put into service, as a standard part of a pipework project.
Testing on completion of new pipework installation
Testing following any alteration to existing pipework
Carried out before purging or commissioning proceeds
A defined procedure, with the result explained clearly.
A tightness test involves isolating the section of pipework being tested, applying and monitoring test pressure over a set period, and confirming whether the installation holds that pressure within the expected tolerance. Where a test does not pass, the location of any leak is investigated and explained before deciding on the appropriate remedial step.
Testing is carried out by Gas Safe registered engineers using calibrated test equipment, and the result — pass, or the fault identified and next steps — is confirmed clearly. Where the test forms part of a wider pipework or purging project, it is sequenced so the installation is not commissioned until it has been confirmed sound.
Test carried out by Gas Safe registered engineers
Calibrated test equipment used throughout
Test pressure applied and monitored over a set period
Fault location investigated where a test does not pass
Result confirmed clearly, in writing where required
Sequenced with pipework and purging work where relevant
Testing supports safe commissioning and ongoing confidence in an installation.
A tightness test is normally required following any new pipework installation or alteration, before an installation or appliance is commissioned or recommissioned, and can also be requested independently where confirmation of an existing installation's condition is needed. We can advise on whether a test is the right next step for your specific situation.
Following new pipework installation
After any alteration to existing pipework
Before appliance commissioning or recommissioning
As a standalone check on an existing installation
Ahead of gas purging works
As part of a wider plant room or refurbishment project
The requirement for testing depends on the specific installation and works involved. We confirm what is needed before arranging a visit rather than applying a standard assumption to every site.
Who we work with
Gas tightness testing for a range of commercial buildings.
Genuine reviews from ComGas customers, submitted through Google.
Lucie Victoria
15 May 2025
Trustindex verifies that the original source of the review is Google.
Excellent service, highly recommend
James Mowat
30 April 2025
Trustindex verifies that the original source of the review is Google.
Incredible service — problems fixed perfectly once again.
Lee, Paul and the team at COMGAS are fantastic. They arrived on time and got straight to work, quickly identifying the root cause of the plumbing and heating issues I was experiencing.
The problems were diagnosed swiftly, I was kept fully informed throughout, and both issues were fixed with impressive speed and precision.
Having worked in the industry for nearly 20 years, I know how rare it is to find reliable, trustworthy, and genuinely skilled professionals — let alone a team this good.
I joked about it at the time, but it’s true: I had the best shower I’ve ever had in this house after they finished the job — and I’ve lived here for 10 years!
I honestly couldn’t ask for more and can’t recommend COMGAS highly enough.
Faz
31 March 2025
Trustindex verifies that the original source of the review is Google.
ComGas replaced my boiler and water tank at short notice. So glad i used them. Thank you
Laura Andrews
26 March 2025
Trustindex verifies that the original source of the review is Google.
Lee came out to the school I work in to look at a problem with our heating, he diagnosed the issue and was able to fix it on the spot in a neat and tidy manor. Would highly recommend
Chloe
26 March 2025
Trustindex verifies that the original source of the review is Google.
I recently used Comgas for a gas and heating service, and I couldn't be more impressed! From start to finish, their team was professional, friendly, and highly knowledgeable. They quickly identified the issue with my heating system and explained everything in detail, offering both short- and long-term solutions.
The technician was punctual and took extra care to ensure everything was running smoothly. I really appreciated their attention to detail and how they made sure to clean up after the work was completed. My home is now warm and cozy, all thanks to their expert service. I highly recommend Comgas for anyone looking for reliable, efficient, and trustworthy gas and heating professionals!
Bec Newey
8 July 2024
Trustindex verifies that the original source of the review is Google.
Messaged Lee on a Sunday evening with request. Instant reply that evening and engineer came next day. Polite, professional and helpful. Thorough investigation and speedy resolution to a leak with sink in wc. Happy customer.
P Duffy
2 April 2024
Trustindex verifies that the original source of the review is Google.
Scott and the team have served me well over several years. Skilled craftsmen. Dependable careful and very cosy-effective. I highly recommend them.
Cilla Trout
22 March 2024
Trustindex verifies that the original source of the review is Google.
Definitely recommend friendly reliable service
Scott was helpful and reassuring regarding our boiler answered our concerns and explained the problem and best course of action thank you for your advice
Gas tightness testing FAQs
Questions about commercial gas tightness testing
Common questions about what a tightness test involves and when it is needed.
A tightness test confirms that the section of pipework being tested holds a set test pressure over a defined period, without any drop that would indicate a leak. It is a specific procedure with its own method, rather than a general visual inspection.
When is a tightness test required?
Testing is normally carried out following new pipework installation or any alteration to existing pipework, and before an installation or appliance is commissioned. It can also be requested as a standalone check on an existing installation where confirmation is needed independently of any other work.
What happens if a test does not pass?
Where a test identifies a leak, we investigate to locate it and explain the finding clearly. Any remedial work required is then separately discussed and agreed before the installation is retested and put back into service.
Can testing be combined with pipework or purging work?
Yes. Testing is frequently carried out as part of a sequence alongside pipework installation and gas purging, so the whole process — pipework, test, purge, commissioning — is co-ordinated as one project rather than arranged separately.
Is tightness testing the same as full gas safety certification?
No. A tightness test is a specific, standalone check of the pipework's soundness. Full commercial gas safety certification covers the wider installation and appliances and sits on its own dedicated page — we can advise on which is relevant to your situation.
Need a gas tightness test on a new, altered or existing installation?
Tell us about the installation, whether it follows recent pipework work, and any timescale or access considerations. We can advise on the right approach.