Gas Pipe Relocation and Connection

A typical case: in the new kitchen the hob goes on a different wall from the old cooker. The old gas outlet now ends up behind the units or in the middle of a cupboard, so it has to be extended or moved. The same happens when individual gas room heaters are replaced by a boiler with radiators or underfloor heating. The gas supply then has to reach one new point, and the old outlets are disconnected and capped.

It helps to separate two different jobs:

• Altering internal pipework: the pipes after the gas meter already exist and only the route changes or an outlet is added. This page covers this job
• A new gas service connection: the building is not yet connected to the gas network, or the connection point is being moved. This is a separate job with more paperwork and is handled by the gas network operator

If gas will no longer be used in the building at all, the pipework is capped off after the meter, and the network operator or supplier is usually involved in removing or sealing the meter.

1. Survey. The gas engineer looks at the existing pipework, the pipe material, where the isolation valves are and where the new appliance will go. They decide whether a short alteration is enough or a new route is needed.
2. Design and documentation. Depending on the scope, a design or at least a sketch is prepared showing the route, pipe size, material and valve positions. For larger changes, or if your gas consumption changes, the network operator may ask for it.
3. Turning off the gas. The gas supply is shut off before any work starts. In a block of flats this is often arranged with the building management if a shared valve on the riser has to be closed. The engineer purges the affected section and checks that no gas remains in it.
4. Installation. The old outlet is cut back or capped, the new pipe is laid, an isolation valve is fitted before the appliance and the appliance is connected. A cooker is usually connected with an approved flexible gas hose.
5. Pressure test. The altered pipework is pressurised and the engineer watches whether the pressure drops. Joints are also checked with a gas detector or leak detection spray.
6. Inspection and commissioning. The installation is inspected and tested, and you receive a written record or certificate. Only then is the gas turned back on and the appliance set up.

A simple move of a cooker outlet usually takes a few hours. A larger alteration in a house can take several days, including preparing the documents and the final inspection.

Gas work is strictly regulated almost everywhere. Only a qualified gas engineer registered under your country's scheme may work on gas pipework, and testing and certification must be done by someone authorised for it. A handy neighbour or a general plumber without gas qualifications must not do it, even if it is only a short piece of pipe.

Before work starts, check the following:

• Registration of the engineer: a reputable tradesperson will show you their registration card or certificate without any fuss
• Documentation: whether a sketch is enough for your job or a proper design by an authorised designer is required
• Network operator requirements: if your consumption changes, you install a new boiler or work is needed near the meter or main valve, ask your gas network operator or supplier
• Building authority: local building regulations differ. Check with your local building authority whether your alteration needs notification or approval, rather than assuming nothing is needed
• Consent in a block of flats: if the work touches the riser or shared areas, agree it with the building management or owners' association

Gas pipework in buildings follows technical standards, for example EN 1775 together with national rules. Meeting them is the job of the engineer and designer, but you should receive a document confirming the work was done in line with them.

How demanding the job is, and therefore how much the work costs, depends mainly on these things:

• Distance and route: a short shift along the same wall is simple, while running through several walls or rooms takes more material and time
• Condition of the old pipework: old galvanised pipe with corroded threads often cannot be safely connected to, so part of it has to be replaced
• How the pipe is run: surface-mounted pipe is the simplest. Pipe buried in a wall chase or behind tiling has stricter rules, for example no mechanical joints that can be undone and valves that stay accessible
• Blocks of flats: if gas has to be shut off for the whole riser, it must be planned with the building management and the neighbours
• Amount of paperwork: whether an inspection certificate is enough or a design and operator approval are needed
• Site readiness: clear access to the pipework and finished rough works save the engineer and you unnecessary delays

During a bigger renovation it is worth considering replacing old pipework in one go and preparing a capped branch for a future appliance. If you plan, say, a gas boiler instead of electric water heating in a few years, tell the engineer now.

• Doing it yourself: it is illegal and dangerous. The supply can be cut off and your insurer may refuse to pay if something goes wrong
• No inspection or certificate: without it, the altered pipework is not approved for use, even if it seems to work
• Wrong materials or joints: only materials and fittings approved for gas may be used, such as steel, copper or certified pipe systems. Threads must be sealed with a product approved for gas
• Hidden valve or joint: the valve before the appliance must stay accessible, not boxed in behind a cupboard without a door
• A long or kinked cooker hose: the hose should be approved, as short as practical, free of strain and away from hot parts of the oven
• Planning only for today: if nobody thinks about future appliances, walls get opened again a few years later

If you ever smell gas, do not switch lights or appliances on or off, close the main gas valve if you can do so safely, open windows and leave the building. Call your local gas emergency number or 112.

Before the engineer leaves, go through these points together:

• The pipe is firmly fixed, with no bends or visible damage
• There is an accessible valve before the appliance and you know how to close it
• Old unused outlets are properly capped
• The cooker hose is approved and is neither stretched nor kinked
• The appliance burns with an even blue flame and the flame safety device works
• You have the pressure test record and the inspection certificate, dated and signed
• You have a design or sketch of the new pipe route
• You know whether anything must be reported to the network operator, building management or building authority, and who will do it