Gas tightness testing changes 2026: Haywards Heath and Sussex

6 days ago

7 min read

Updated 11 September 2026. The new testing procedure applies from 1 October 2026.

If your gas installation passed its checks last year, it is understandable to be surprised if an engineer now says it needs attention.

The way gas tightness tests are assessed is changing. A result that could have passed under the previous procedure may not pass under the new one. That can mean extra checks, a repair or, where necessary, turning off an appliance or the gas supply to keep the property safe.

This guide explains what is changing and what you can expect from us at Smart Heat Experts, whether you are in Haywards Heath, Burgess Hill, Hassocks or a nearby Sussex village.

The changes at a glance

When: from 1 October 2026, for installations covered by the updated standard.
What you may notice: more time checking the gas pipework and appliances separately.
What a failed test means: we need to find the problem and decide how to put it right. It does not automatically mean a new boiler.

The updated standard is called IGEM/UP/1B Edition 4. It covers small natural gas, LPG and LPG/air installations within its stated limits. Read IGEM's overview.

What is a gas tightness test?

In plain English, it is a check for gas escaping from the installation.

We connect a sensitive pressure gauge and watch how the pressure behaves during a controlled test. The result helps us decide whether further investigation is needed.

This is separate from the water pressure shown on the front of your boiler. Adding water to your heating system will not fix a gas leak.

Liquid manometer photographed during Smart Heat Experts' gas leak investigation in Burgess Hill

An actual job photo from our Burgess Hill visit: a liquid pressure gauge, also called a manometer. One photograph cannot show whether pressure stayed steady throughout a test.

“It has been fine for years. Why is it a problem now?”

This is likely to be one of the biggest questions customers ask us.

Yes, an installation that passed under the old procedure may fail under the updated one. Gas Safe explains that this can happen even where the installation was previously considered safe.

The assessment has changed

Previously, the allowance for a small pressure drop depended on the meter type. The updated procedure considers the volume of the gas installation being tested.

That means the space inside the gas installation, not the size of your rooms.

We need to establish where a pressure drop is coming from

A small overall drop is not enough on its own to say everything is acceptable. The engineer must establish that it is not coming from the gas pipework.

If the pipework test shows a detectable drop, the escape needs to be found and repaired, or the installation made safe. Gas Safe's explanation of the pipework requirement.

A previous pass does not override today's result

A different result does not, by itself, prove that the previous engineer did anything wrong. It also does not automatically mean the latest visit caused a fault. We need to look at the work, the history and what the current checks show.

The change in standard does not physically create a leak. It changes how the test is assessed and what the engineer must establish before accepting the result.

If an installation fails the updated procedure, we cannot switch back to the old one simply to give it a pass. Read Gas Safe's customer factsheet.

A real Burgess Hill repair: a faulty gas valve, not a new boiler

In June 2026, a homeowner in Burgess Hill contacted us after having a new gas meter fitted. A leak had been found during the checks. It stopped when the boiler was isolated, and the supply had been capped to leave the property safe.

The customer needed the fault investigated and the boiler working again.

First, Gavin checked where the problem was

When Gavin attended, the gas pipework held pressure when tested separately. When the boiler was included, the pressure dropped.

That helped narrow the investigation to the boiler. Gavin also reported a concern about the supply pressure to the gas supplier. The boiler and supply were left isolated while the issue was being dealt with.

Then we sourced the right part

The repair needed a replacement gas valve. This is the component that controls gas entering the boiler's burner.

We checked the boiler details to identify the correct valve, then arranged a return visit. On 23 June, Gavin replaced it, carried out a gas tightness test and checked the boiler's combustion using a flue gas analyser. His completion note confirms that the boiler was left working.

For this customer, the answer was a gas valve repair. The boiler did not need replacing.

Flue gas analyser photographed during the Burgess Hill boiler gas valve repair visit

Gavin's flue gas analyser, photographed during the Burgess Hill repair visit. It checks combustion gases. This is a separate check from the gas tightness test.

This job took place before the October change. It shows why checking the pipework and boiler separately matters, but we are not presenting it as a failure caused by the new rules.

Every job is different. We will explain what we find at your property before recommending a repair.

Does every pressure drop mean the gas has to be turned off?

No. The result needs to be assessed properly.

A limited drop can sometimes be acceptable with existing appliances connected, but only when the relevant limits and safety conditions are met. These include no reported smell of gas, satisfactory pipework checks and the engineer's assessment of the particular installation.

For pipework on its own, or an installation containing only new appliances, the requirement is no perceptible movement on the gauge. In everyday terms, no detectable change during the test.

If an appliance cannot be isolated for the pipework check, the connected test must also meet that no-movement requirement.

Where the result is not acceptable, the escape must be traced and repaired or the installation made safe. Gas Safe's technical explanation.

If we find a problem at your home

You may have booked a routine service and suddenly find yourself discussing a repair. We know that is frustrating, especially if it affects your heating or hot water.

We will take you through it in three steps.

1. Explain what we have found

We will tell you what the checks show, whether we have located the fault and what still needs investigating.

You should also be clear about which appliances you can use and which must stay off.

2. Make the installation safe

Where an appliance or installation cannot safely remain in use, we will explain why it needs to be isolated or disconnected and follow the gas industry's unsafe situations procedure.

We will explain any warning notice and how the installation has been left. Please tell us if losing heating, hot water or cooking would create particular difficulties.

3. Agree the next steps

We will explain the proposed work, likely costs and whether we need parts or another visit.

Extra investigation and repairs are not automatically included in a routine service price. We will explain additional charges and seek agreement before extra chargeable work, while dealing promptly with any immediate safety issue.

You can ask questions or seek another suitably qualified engineer's opinion. Follow the safety advice in the meantime and do not use an appliance suspected to be unsafe until it has been checked and made safe. HSE advice for homeowners.

Questions we expect customers to ask

Will you need to lift my floorboards?

Not just to work out the installation volume. Engineers can use professional judgement to assess concealed pipe routes. Finding and repairing a leak is a separate matter and may require access, which we would discuss with you. Gas Safe customer factsheet.

Will the visit take longer?

It may do, especially if appliances need to be isolated and tests repeated. There is no single extra time allowance for every home. We will explain what is needed and keep you updated.

Do I need to book an extra test in October?

There is no blanket requirement for every homeowner to book an additional visit on 1 October simply because the procedure is changing. Keep up with appropriate servicing and safety checks, and have suspected faults investigated promptly.

Our standard boiler service includes a gas tightness test. See what our boiler service includes.

What should I do before your visit?

Keep the gas meter and boiler accessible. Tell us about any gas hobs, cookers or fires elsewhere in the property, and mention any smell of gas or recent gas work.

Leave moving connected appliances and operating their isolation valves to the engineer.

Does this apply to homes using LPG?

The standard includes small LPG installations within its scope, but the requirements depend on the fuel and installation. The same allowances cannot simply be used for every home. IGEM scope.

What about landlords and tenants?

Landlords' existing gas safety responsibilities continue, including the required annual checks on the gas appliances and flues they provide and prompt action on defects.

A tightness test does not replace the complete landlord gas safety check. Tenants should pass warning notices and repair advice to their landlord or managing agent promptly. HSE landlord guidance.

Smell gas? Do not wait for a routine appointment

For a suspected mains gas escape, call 0800 111 999 immediately from a safe location outside.

Avoid flames, smoking and operating electrical switches. Open doors and windows if safe. Turn off the gas at the meter control valve only if you know how and can reach it safely.

Leave the affected area and follow the emergency operator's instructions. For an LPG escape, contact your LPG supplier's emergency service. If there is a fire or immediate danger to life, call 999.

Do not wait for us to return a message or try to repair a gas escape yourself. HSE emergency advice, SGN emergency contact.