Please note that only Gas Safe (this has superseded Corgi accreditation) registered engineers can work on gas appliances. All gas appliances need to be registered with Gas Safe when installed or changed. This includes cookers, gas hobs and boilers.
There are strict limits for the amount of gas required for each and every appliance. If there is not enough gas available for the rating of the appliance, then the appliance could be dangerous.
With the previous standard for gas valves, on old appliances, the engineer could make a measurement of the gas pressure coming through the pipework and then do a rough calculation to establish whether there would be enough gas for the appliances before it was connected. However, the new type of gas valve on modern appliances makes this estimate impossible to do – there is no substitute for actually installing the appliance and testing it in situ to see if it receives the correct amount gas needed for the appliance to burn correctly.
This means that when the appliance is commissioned, the most important check is whether there is enough gas, otherwise the appliance will be deemed unsafe. If it is, then the only solution is to adapt the existing pipework or re-run it in a larger diameter so that enough gas is delivered to all the appliances working off that meter.
Be aware that re-running the gas piping will result in additional costs.