IGEM issues recommendations for low supply working practices

01/08/2019 09:00
August 2019 - IGEM issues recommendations for low supply working practices.jpg

IGEM's Low Pressure Supply Working Group is seeking industry comment on a number of recommendations designed to address the root cause of low supply issues on domestic gas supplies.

Following a series of cross-industry meetings, IGEM’s Low Pressure Supply Working Group has concluded that low pressure is not a widespread issue and that the design of the UK distribution network remains fit for use with the majority of gas appliances currently on the market.

“However, it has acknowledged that over recent years there has been a progressive increase in the capacity of domestic boilers. The major reason for this is the increase in the average net heat input of domestic boilers being supplied, largely driven by the requirement for instant hot water for showers and baths,” said Ian McCluskey, IGEM’s Head of Technical Services & Policy.

“As a result of the discussions, the group concluded that procedures put in place to deal with incidents of low pressure can vary dramatically across the industry. This can sometimes mean the customer is unable to use certain appliances once they are installed.”

The group also concluded there is a need for greater cooperation across the industry to improve communication and to increase the level of understanding of all aspects of the gas system across the board.

“In particular, the group has identified a need for clarification on the pressure requirements for the low pressure supply system and for processes and procedures to be agreed across the industry,” said Mr McCluskey.

“It is hoped this will enable the various industry standards and guidance to become consistent in their requirements and will mean manufacturers’ instructions match those requirements,” he added.

The Low Pressure Supply Working Group was formed by IGEM in response to a request from the Standards Consultation Forum (SCF), back in 2016.

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.

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 Cadent, SGN, Northern Gas Networks and Wales & West Utilities, to investigate and formulate a response.

Unfortunately, many in the industry felt the resulting Energy Networks Association (ENA) gas industry bulletin did not sufficiently address the issue and IGEM was subsequently approached to carry out further work in this area.

IGEM sought agreement from the Technical Coordinating Committee (TCC) to undertake the work on behalf of the industry, which was tabled at a TCC meeting on 6 June 2016. The request was accepted and the first meeting was convened on 8 June 2017 and chaired by Vic Tuffen, Chairman of IGEM’s Gas Measurement Committee (GMC).

The working group was entitled LP Supply Pressure Working Group and IGEM wrote to all its consultees seeking their involvement with the work. There was cross-industry engagement with the working group and 24 representatives at the first meeting from amongst the GDNs, meter asset managers (MAMs), large businesses, installer groups, sole traders, gas appliance manufacturers, independent consultants, BSI, HSE and Gas Safe Register.

The format for the working group was a workshop with background information prepared for each meeting and a number of questions for the members to debate in small groups. Each group was made up of representatives across industry to stimulate conversation between the parties and arrive at a consensus.

The initial meetings were intended to cover the following aspects of the work:

  • Legal requirements and guidance 
  • for the natural gas (NG) low pressure
  • supply network
  • Published standards by BSI and IGEM
  • Manufacturers’ instructions
  • Organisations’ internal guidance
  • Issues raised by the industry

The outcome of the work was intended 
There was consensus that the current arrangements and associated legal framework were fit for purpose, but that there was a need for cooperation across the industry to improve communication and increase understanding across all aspects of the gas system.

In particular, achievement of the following was considered:

  • Industry to provide clarification on the pressure requirements of the low pressure supply system
  • Agree on the processes and procedures across the industry
  • Enable various industry standards and guidance to become consistent in their requirements
  • Match manufacturer’s instructions with those requirements
  • Limit the capacity of a standard domestic supply
  • Establish the extent of low pressure incidents on domestic installations.

There were ten meetings of the working group with the last meeting held on 6 February 2019.

The working group developed a set of recommendations to address industry concerns. These cover limits on the normal kW capacity of a domestic gas supply service, harmonise procedures for installing appliances and cover precommissioning, commissioning, post commissioning, conditions for reporting low pressure supply, how emergency service providers should respond and downstream testing methods for low pressure.

Domestic (LP) supply capacity It is proposed that a normal domestic gas service be capped at 64kW. 

This would inform the designer and/or installer to consider the load requirements and suitability of the appliances before pricing and attending site. If necessary, there is the option to approach the gas transporter (GT) for a service of increased capacity before installation.

This consideration was born from the recognition that, over recent years, there has been a progressive increase in the capacity of domestic boilers. The main reason for this is the increase in the average net heat input of domestic boilers being supplied, largely driven by the requirement for instant hot water for showers and baths.

Proposed procedures for installing appliances 
The following are the proposed procedures for installing appliances.

When considering installing an appliance, confirm the pressure at the outlet of the meter is an average of between 18.5mbar to 22mbar as soon as practicable, with all appliances within the property operating at a high operating load over a six-minute period.

A high operating 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 load (e.g., for boilers, depending on the appliance type, by running two hot water taps on full flow), all other heating appliances at maximum load and any other appliances at 50 per cent load (e.g., by lighting two burners of a four burner hob).

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.

Verify the appliance inlet gas pressure as per the manufacturer’s instructions and operate the installed appliance at maximum appliance input. The reading shall be as specified by the manufacturer.

Maximum appliance input is as specified by the manufacturer in the commissioning instructions. For example, commissioning/chimney sweep mode, or where not specified, the appliance is operating at its maximum appliance input, e.g., hot water mode on a combination boiler.

Note: Be aware of any pressure loss between the inlet test point and the inlet to the appliance isolation valve.

Post commissioning
On completion of the commissioning process, confirm the pressure at the outlet of the meter is between 18.5mbar to 22mbar with all appliances within the property operating at a high operating load for a period of six minutes.

Conditions for reporting low pressure supply

Engineers may encounter reports of poor pressure or be unable to achieve the appliance’s required inlet pressure and/or heat input during their work. In such instances, confirm the pressure at the outlet of the meter is an average of between 18.5mbar to 22mbar with all appliances within the property operating at a high operating load over a six-minute period. If the average pressure is below 18.5mbar, report to the Gas Emergency Service Provider (ESP) contact centre.

If it is known that these pressures are affecting the safe performance of an appliance, or the appliance is deemed to be unsafe, then the Gas Industry Unsafe Situations Procedure (GIUSP) must be followed.

The process for reporting low pressure The proposed reporting procedure is: 

1 If the average working pressure is outside range of 18.5mbar to 22mbar at the outlet of the meter, the engineer should contact ESP and obtain a reference number.

2 Advise the ESP of:

  • Low pressure (or high pressure) readings
  • Engineer’s Gas Safe Register number
  • Engineer’s phone contact number

3 If possible, the engineer should wait for the ESP, who should call within two hours (if the appliance is new, the engineer must wait for the ESP).

4 The ESP takes responsibility for investigating the pressure issues and sharing the outcome of the investigation with the customer and installer, as appropriate.

Note 1: The ESP First Call Operative (FCO) will test the pressure at the outlet of the meter, expecting an average of between 18.5mbar to 22mbar with all appliances within the property operating at a high operating load over a sixminute period

Note 2: The customer may be required to contact their gas supplier. The details of the supplier and the means of contacting them is included on the gas supplier’s invoice.

Note 3: The GTs need to be aware of incidents of low pressure on the network in case the issue is not confined to one property and action is required to maintain the supply to a number of properties.

If the consumer is not satisfied, after the network operator has concluded the investigation, the GT complaint procedure should be invoked by the customer, whereby the ESP should leave contact information with the customer.

Supply your comments by 26 August 2019 to technical@igem.org.uk or send them for the attention of Peter Hurst, IGEM Technical Officer, IGEM House, 26 & 28 High Street, Kegworth, Derbyshire DE74 2DA.

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