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.
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Nick
3 September 2026
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Matt from ComGas Services UK Ltd was very professional, polite, friendly and quick installing a new shower in my bath (and at a better height for me) and a much easier press-in plug for my sink! He left the place spotless. This is the kind of service and installation people dream about - a 5 star service (see photos).
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Laura Peters
17 August 2026
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I have used Comgas twice and both times have been very happy with the service. Very friendly and honest. The most recent time, the job turned out to be a lot bigger than they initially thought but it was no issue and Paul stayed the extra time to make sure the job was done properly! He was really tidy, took a lot of care with the work that was done and took the time to explain what he was doing and why. Pleased to have found a reliable heating company!
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James Ross
8 August 2026
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I had an issue with my boiler and Matt came out to have a look the same day and managed to fix it. Great, professional service. Highly recommend.
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Ian Chevalier
11 June 2026
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First time we've used this company and it won't be the last. Very professional and efficient in everything they do and Matt was excellent in his knowledge and efficiency when dealing with our gas and plumbing problems.
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Karen Flackett
20 May 2026
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Excellent service. Matt came & fitted 2 taps & waste pipes he was polite & friendly & carried out the work efficiently & in a timely manner.
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Paul Norris
30 April 2026
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Fantastic experience from the chaps at ComGas! Special thanks to Matt who removed an old boiler and replaced with a new energy efficient to satisfy the demands of a five bed house with a few bathrooms/baths and showers. The ComGas admin team and Lee were fantastic too on the booking and administration side of things!
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Julie Galvin
21 April 2026
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Here at St Joseph's we have worked with Comgas for a number of years. They have completed big projects and undertake regular maintenance for our school. They price fairly, and their work is completed to a very high standard. All the engineers carry a DBS which makes life so much easier when trying to book an engineer visit.
On the rare occasion that we have an emergency I can trust that Lee will get one of his engineers to respond quickly and efficiently.
Nothing is too much trouble and no job is too small.
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Chesca Haley
16 April 2026
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Lee and the team are amazing! So helpful, so knowledgeable and really look after their customers. Highly recommend.
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Sarah Rogers
6 April 2026
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Absolutely amazing service, always a thorough job and very knowledgable. Really nice guys too. Lee has sorted numerous issues at work and around our house. We have recommended to friends and family who are also very happy
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Alison Molan
25 March 2026
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Lovely engineers, Matt and Jack, were a pleasure to have in the house. Thorough, knowledgeable, tidy and polite. Would highly recommend.
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.