Low Pressure Supply Working Group

What is the Low Pressure Supply Working Group?

A group of experts bought together to discuss incidents of low pressure on the gas distribution network increasingly reported by installers. 

Who’s involved?

The Low Pressure Supply Working Group was put together in response to a request from the Standards Consultation Forum (SCF). It is made up of representatives from: British Gas, Cadent, DNV GL, Energy Assets, Global Energy, Heating and Hot Water Industry Council (HHIC), HomeServe, Health & Safety Executive, National Grid, Ofgem, Organisation of Professional Gas Operatives (OPGO), SGN, Tuffentech and Wales & West Utilities.  

Why was the investigation required?

Following an increase in the number of complaints from installers concerning incidents of low pressure on the gas distribution network, the SCF instructed the operators of the gas distribution networks, Cadent, SGN, Northern Gas Networks and Wales & West Utilities, to investigate and formulate a response.

Unfortunately, the resulting Energy Networks Association (ENA) Gas industry bulletin entitled Response to poor pressure reports was not seen by industry to sufficiently address the issue. Subsequently the SCF approached IGEM to carry out further work in this area.

Output

Following a series of meetings the Low Pressure Supply Working Group concluded that low pressure is not a significant issue and that the design of the UK distribution network remains fit for use with the majority of gas appliances currently on the market. They acknowledged however, that the next generation of appliances with increasing net heat input may prove more problematic.

As a result of the discussions it was identified that the procedures in place to deal with incidents of low pressure vary across industry. This often means that the customer is unable to use the appliance they purchased and that has already been installed.

The group identified two areas of mutual concern for installers and gas emergency service providers (ESPs). These were: the Gas Appliances (Safety) Regulations 1995, the requirements of which should be factored into the supply of gas to premises and the appliance manufacturer’s instructions that should reflect the design and capacity of the gas distribution network.

The working group has facilitated further discussions covering these areas and considered what the typical load should be for a domestic property due to the increasing capacity of domestic appliances on the market which may end up exceeding the operating capacity of the network.

Agreed procedures

What follows in a summary of the procedures agreed by the working group in order align the response of installers and gas emergency service providers to incidents of low pressure on the gas distribution network. Full details of these procedures is available below/on request.

Confirming correct gas pressure

There are generally two scenarios in which an installer will be required to confirm the correct gas pressure at the appliance inlet these are:

  1. On commissioning an appliance

  2. Following reports of poor pressure/failure to achieve operating pressure and/or heat input.

Note: In all instances where the appliance inlet pressure cannot be achieved ensure pipework is correctly sized before implementing the ‘Reporting of Low Pressure’ process.

As soon as is practical when installing an appliance, confirm that the outlet pressure of the meter is between 18.5 mbar to 25 mbar with all appliances within the property operating at a realistic normal load* over a six-minute period.

Note: Ensure there is enough pressure at the meter outlet minus the internal pipework designed pressure loss to supply the new appliance with adequate inlet pressure.

* Realistic normal load is the normal maximum operating load for the entire gas installation in the property for a period of high demand.  To replicate this, operate the highest output appliance at its maximum output, e.g. for boilers heating or hot water, dependant on appliance type, all other heating appliances at maximum output and any other appliances at 50 per cent load e.g. hob with four burners only two are lit.

 

Low pressure gas system design pressures