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This article was first published in the October 2021 edition of Registered Gas Engineer

Every day, Gas Safe Register’s Technical Team answer calls and emails from gas engineers. They may need support in classifying an installation or just need to check something with the highly experienced and helpful Technical Officers. Here are just a few of questions that are asked most frequently – and the answers.


While I was servicing a boiler, I found that the inlet working pressure was low when testing as per the manufacturer’s instructions (MIs). How do I classify this?

When you encounter an appliance that has low working pressure, a few variants need to be considered before you decide how to classify it. The main issue is whether or not the appliance is working safely. Where a boiler has a working pressure below the manufacturer’s minimum recommended requirements, but the gas rate is correct, and flue gas analysis shows that the appliance is burning correctly, then this is not necessarily unsafe, and could be left as Not to Current Standards (NCS). You should seek further guidance from the manufacturer in this case, and follow its advice regarding classification.

However, if the appliance safety or any other gas appliance in the property is being affected by the low pressure, you must follow the guidance given in IGEM/G/11, the Gas Industry Unsafe Situations Procedure (GIUSP). You can find further guidance in Technical Bulletin 129.

I have a domestic boiler in a commercial setting. Do I need commercial qualifications to work on this?

When considering which qualifications you need to work on an appliance, you must first know how the manufacturer categorises the appliance. As a rule, appliances under 70kW are deemed domestic: however, there are some exceptions and you should check with the manufacturer. Any appliance over 70kW will always be a commercial appliance and you will need non-domestic qualifications to work on it.

Where a domestic appliance is fitted in a commercial building, it is the appliance classification that matters. For instance, if there is a stand-alone domestic boiler fitted in a factory, then you need CENWAT to work on that appliance.

However, where multiple domestic appliances with an aggregate of over 70kW are fitted in series in the same room – for example two 40kW boilers fitted together, then the room becomes a plant room. As such, you need commercial knowledge and qualifications as well as the domestic boiler qualification.

You should also know the limitations of the pipework on which you can work. If you have domestic qualifications, you can work on up to a U16 meter, 35mm copper or 1¼” steel, and an installation volume of 0.035m3. Anything over this requires non-domestic qualifications.

There is no equipotential bonding on the meter but the electrician says it’s fine. Are they right?

When a gas installation does not appear to have the correct equipotential bonding fitted, the gas engineer’s responsibility is to inform the responsible person, in writing, that they should employ a competent electrician to check that the installation is electrically correct.

Equipotential bonding is an electrical issue, not a gas safety one. Ultimately, if the electrician states that the bonding is correct or not needed, then that should be taken as correct. For instance, where the gas service pipework (mains gas) is run in PE pipe, there may be no need for equipotential bonding. This decision is for a competent electrician to make.

I’m replacing a boiler and the old chimney goes over a boundary. The neighbour has given their permission to fit the new boiler in the same place. Can I do this?

No. When you install any gas appliance, it must be installed in accordance with all relevant British standards, regulations, and the manufacturer’s instructions. BS 5440 Part 1 and Building Regulations Approved Document J state that any chimney must terminate at least 600mm from a facing boundary, and 300mm if running parallel to the boundary. Some manufacturers may allow these distances to be reduced if using plume management kits. However, no chimneys should terminate over the property boundary.

Even if the neighbour gives their permission to terminate the chimney on to their property, this is not permitted because, in the event of the property changing hands, the new owner may object. In this instance, it should be re-routed, and the boiler may need to be re-sited.

What are the requirements for soldering gas installation pipework in a caravan? Can I use any solder?

When installing pipework in a caravan, static mobile home or motor home, it is not permitted to use soft soldered fittings. Only mechanical fittings or hard soldered (brazed) fittings should be used.

There some confusion about the qualifications required to work on a static mobile home. The qualification required is leisure accommodation vehicles (LAV), not residential park homes. Both qualifications show as ‘caravans’ on the back of your Gas Safe ID card. If you are unsure whether you are qualified to work on an installation, you should always check with Technical Team before carrying out any gas work. You can find more information about working on LAVs, RPHs and holiday accommodation in Technical Bulletin 063.

Working in rental properties


I’m doing a landlord’s gas safety record (LGSR) check and have a hob in a room with no window, ie, an internal room. Should I fail the LGSR?

When carrying out an LGSR, and there is a cooker or hob fitted in an internal kitchen, this does not necessarily mean that the appliance is unsafe.

All cooking appliances should be fitted in a room with a window or door direct to outside. This is for purge ventilation not combustion ventilation. If there is no window or door to outside, then the kitchen becomes an internal kitchen, and the guidance given in Technical Bulletin 005 should be followed.

TB 005 states that alternative types of purge ventilation should be installed, such as extract fans that vent outside or trickle vents into a conservatory. The requirements vary in the different UK nations and you can find these in the Technical Bulletin.

However, if there is no purge ventilation in the kitchen at all, this is a Building Regulations issue, not a gas safety one. As long as the kitchen is bigger than 10m2 the installation would usually be deemed Not to Current Standards (NCS).

What is the new rule about due dates on landlords’ gas safety record checks?

When the GSIUR was updated in 2018, Regulation 36a was added. This states that an LGSR check may be carried out up to two months before the renewal date, and the renewal will remain the same. For instance, if the LGSR is due on 1/10/2021, it can be carried out any time from 1/8/2021, and the renewal date for next year will be 1/10/2022. If the check is carried out early, the landlord must be able to produce the previous two years’ records.

None of this affects the way you carry out the safety check in any way: the rule is designed to minimise the risk of LGSRs running out and the tenant being left without a valid record.
You must not post-date the record. You may added the extended renewal date on the record if you wish, though this is not a requirement.

You can find more information on this ruling in Technical Bulletin 055, as well as at


Does a gas cooker only need a visual inspection on the LGSR?

This depends who owns the cooker. If it’s the tenant’s own appliance, then it is not the responsibility of the landlord, and so requires only a visual inspection.

If it is owned by the landlord, then it must be fully checked, with all other appliances, in accordance with Regulation 36 of the Gas Safety (Installation & Use) Regulations 1998 (GSIUR). Further guidance on landlords’ responsibilities can be found in Technical Bulletin 055, or at


More information

This article provides at-a-glance information on some of the questions asked by gas engineers. You can find more in-depth information on some of these topics in the Technical Bulletins published by Gas Safe Register. You can read and download all Gas Safe Register Technical Bulletins by logging into your online account at:

  • Technical Bulletin 129: Boiler inlet gas pressure measurement
  • Technical Bulletin 005: Gas cookers in internal kitchens
  • Technical Bulletin 055: Duties of landlords
  • Technical Bulletin 063: Carrying out gas work on leisure accommodation vehicles, residential park homes and holiday
  • BS 5440-1: Flueing and ventilation for gas appliances of rate input not exceeding 70kW net (1st, 2nd and 3rd family gases) – Specification for installation of gas appliances to chimneys and for maintenance of chimneys.


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