On 31st May 2014 a revised British Standard (BS) 6798: 2014 ‘Specification for selection, installation, inspection, commissioning, servicing and maintenance of gas-fired boilers of rated input not exceeding 70kW net‘ was introduced, replacing the previous 2009* standard.
*BS 6798: 2009 ‘Specification for installation and maintenance of gas-fired boilers of rated input not exceeding 70kW net’.
For many Gas Safe Registered engineers this revised British Standard will have an impact on their day-to-day work given that it applies to ‘domestic’ sized central heating boilers (those boilers <70 kW net).
Given the importance of this Standard to many of us in the gas industry, the following is a general overview of the revised BS 6798 and how it differs from its 2009 version.
Please note that not every point of the Standard is covered here and therefore, Gas Safe Registered engineers are advised to obtain a copy of BS 6798: 2014 from either BSi or for subscribers to Gas Safe’s technical library, Gas Safe Register.
BS 6798 – Forward
The general information on the preparation of the document; its date of introduction; information about the document, etc. is familiar and largely unchanged.
However, a new sub-heading of ‘Use of this document‘ is included which informs that the recommendations (presented in Commentary) form part of the specification and thus, to comply fully with the specification, all its provisions need to be complied with.
The list of regulations under ‘Compliance with a British Standard cannot confer immunity from legal obligations‘ has been extended and amended, to cover Scotland, Northern Ireland and Isle of Man in addition to England & Wales.
Text has had some minor amends to introduce standards related to the design of full heating systems; namely BS EN 12828, BS EN 12831 and BS EN 14336.
Other minor amends include the withdrawn status of BS 5449; competency covered by new Clause 4 (moved and amended from Annex A of the 2009 standard) and a new Note 7 covering LPG/air mixtures used in the Channel Islands or the Isle of Man.
2. Normative references and 3. Terms & Definitions
Minor amends to the list of references (standards updated) and definitions used.
Moved from 2009 Annex A and greatly expanded upon to cover Gas Safe Register; ACS; approval bodies and competency requirements by country/region.
5. Environmental conditions
A new clause covering the disposal/recycling of existing appliances and materials; optimisation of energy used and controlling harmful emissions.
6. Selection of equipment and pre-installation
6.1 Exchange of information and planning
Changes to text with ‘Consultation with official bodies‘ moved to appear first; reference to IGEM/UP/17 included in point f) to ‘Liaison between the various trades‘ and amended 2009 Note 2 (now a second bullet to f)), which discusses the requirements of Building Regulations with regards to inspection provisions for chimney systems in voids.
6.3 Condensing boilers
6.3.1 General – minor amends to Commentary.
22.214.171.124 General – text moved from 2009 Standard to appear sooner, plus new text a) to g) on general location considerations. Additionally, minor changes to Commentary.
6.3.3 Siting of chimney outlet – new Notes 1, 2 and 3; new point 5) on areas used for car parking and new point i) covering the limitation on roof installations and horizontal chimney terminations through tiled roofs for room-sealed, fan-assisted boilers.
6.3.4 Selection of condensate discharge point – an area of the Standard that see’s one of the biggest changes. The text has been amended and expanded upon from 2009 4.3.4 to give priority to internal discharge of condensate to combat freezing issues.
Additionally, previous Figures in 2009 Standard have been amended and moved to a new Annex A – discussed later in this update.
6.3.5 Combined discharge from pressure relief valve and boiler condensate drain – new text and Commentary covering the special conditions that apply for combined pressure relief discharge and condensate discharge pipe.
6.3.6 Use of condensate pump – amended text from 2009 126.96.36.199.
6.3.7 Choice of discharge pipe
188.8.131.52 Separate pressure relief valve and condensate discharge pipes – a new sub-heading.
184.108.40.206.1 Condensate removal – new text sign posting the requirements of 220.127.116.11.2 to 18.104.22.168.4.
22.214.171.124.2 Material – new Commentary on the jointing of condensate pipe.
126.96.36.199.3 Diameter of internally run condensate pipe – a new sub sub-heading. Amended 1st paragraph to introduce internal diameter (ID) of pipe instead of the previous use of outside diameter (OD); minimum 19mm (ID) instead of 22mm (OD). New Commentary to explain the switch to internal diameter.
188.8.131.52.4 Diameter of externally run condensate pipe – a new sub sub-heading. As for 184.108.40.206.3 an amended 1st paragraph to introduce the change to internal diameter for externally run pipe; from 32mm (OD) to 30mm (ID). New Commentary to explain the switch to internal diameter.
220.127.116.11 Combined pressure relief valve and condensate discharge pipes – a new sub-heading.
18.104.22.168.1 Discharge pipes combined outside the boiler during installation – a new sub sub-heading, text and Commentary covering the visibility of the combined discharge to the installer.
22.214.171.124.2 Removal by gravity – a new sub sub-heading and text covering 6 points – a) to f) – required to be met when combining a gravity discharge outside the boiler case.
126.96.36.199.3 Removal with condensate pump – a new sub sub-heading and text covering the 9 points – a) to i) – required to be met when using a condensate pump.
188.8.131.52.4 Discharge pipes combined internally within the boiler case – a new sub sub-heading.
184.108.40.206.4.1 Removal by gravity – a new sub sub-heading and text covering the combined discharge of pressure relief valve and condensate within the boiler via a single connection point at the boiler.
220.127.116.11.4.2 Removal with condensate pump – a new sub sub-heading, text and Commentary covering the requirements of using a condensate pump
6.3.8 Position and termination of the condensate drainage pipe
Minor amends to the text; a new point e) covering rainwater downpipes; new Note 3 covering the difference between foul and storm drains; new Note 5 explaining that there is no length restriction for condensate pipe when installed in accordance with the requirements of the Standard and new Note 6 stating that the condensate pump manufacturer needs to be consulted for any length restrictions.
6.3.9 In-line condensate neutralizer devices
18.104.22.168 In-line condensate neutralizer devices fitted to a dedicated condensate discharge pipe – a new sub head, repositioned text from 2009 4.3.5 and Note. Subtle change to text from prohibiting the use of neutralizers unless the manufacturer states otherwise to allowing their use unless the manufacturer states otherwise.
A new Commentary on point c) of 22.214.171.124 regarding servicing activities and the need to either replace the neutralizing medium annually or checking the acidity of condensate downstream of the device on a periodic basis, replacing the neutralizing medium as necessary.
126.96.36.199 In-line condensate neutralizer device fitted to a combined pressure relief valve and condensate discharge pipe
188.8.131.52.1 Discharge pipes combined outside the boiler during installation – new text covering the position of the connection of a combined pressure relief and condensate discharge to after the outlet of the neutralizer, unless the manufacturer allows a connection to its inlet.
184.108.40.206.2 Discharge pipes combined internally within the boiler – new text and Commentary covering the installation of a neutralizer to a single combined connection point at the boiler only where the manufacturer of the neutralizer allows.
6.4 Materials and components & 6.5 Boiler rating – minor text changes.
7.2 Chimney system – text added on concealed chimney systems in voids needing to comply with the requirements of Building Regulations and in Commentary, signposting for additional information for vertical condensing flexible flues in Gas Safe Register’s Technical Bulletin 139.
7.3 Siting of the appliance
7.3.1 General – new 1st paragraph covering the suitability of the floor, both in bearing the weight of the appliance when full of water and needing to be flat and level.
7.3.3 Airing cupboard installations
220.127.116.11 Airing cupboard installations where the space is to continue to be used as an airing cupboard – a new sub sub-heading.
18.104.22.168 Airing cupboard installations where the space is no longer to be used as an airing cupboard - a new sub sub-heading, text and Commentary covering the requirements of reusing an old airing cupboard and the need for appropriate labelling.
7.3.5 Bathroom and shower room installations – new paragraph – 22.214.171.124 – on electrical isolation for the appliance being protected by a 30mA RCD.
7.3.8 Roof space installation – new Commentary formed from 2009 point e) on providing a guard to prevent contact between stored articles and the boiler.
7.3.11 Ambient conditions – new clause covering the area in which the boiler is installed with regards to it being clean, dry and ensuring good ventilation to limit the ambient temperature to minimum and maximum levels stated by the appliance manufacturer.
7.4.3 Pressure relief valve – point a) amended and expanded upon to allow other materials that are not metallic to be used where this material is acceptable to either the boiler or pipe manufacturer (2009 126.96.36.199 a) stipulated metallic only).
Additionally, a new point b) regarding pressure relief for sealed system boilers installed below ground-level (basements) has been made from text within 2009 standard.
188.8.131.52 clause has a minor amend to remove a sentence that discussed minimum thickness of insulation in accordance with BS 5422, Annex H.
7.6.3 a) Single point of electrical insulation – a new sub-heading
In addition, a new clause b) Two (or more) separate and independent points of isolation has been included with text and Commentary discussing multiple points of isolation and its various requirements.
7.7.2 Open systems
184.108.40.206 Feed and expansion cistern – minor amends to text with reference to the UK National Annex to BS EN 14336; internal diameter of warning/overflow pipe stated at 19mm and Commentary expanded to discuss minimum dimensions of support beyond the cistern that it supports (150mm on all sides).
220.127.116.11 Hot water storage vessel & 18.104.22.168 Filling and make-up equipment – a minor amend with mention of UK National Annex to BS EN 14336 inserted once again.
22.214.171.124 Methods of filling sealed system – a minor amend to reference schedule 2, Section 8, paragraph 24 of the WRAS Water Regulations Guide.
7.8 Selection of heating system controls
New heading, text and Commentary relating to installing controls specified by the appliance manufacturer.
8.1 Inspection – text amended to create a new point a) which discusses the work undertaken is in accordance with the Standard, manufacturer’s instructions, and GSIUR; a new b) concerned with the legal requirement in some parts of the UK to have CO alarms installed which must be complied with; and 2009 Commentary and Recommendations altered to form a new Note 1 with bullets that includes additional detail on multiple points of electrical isolation.
8.2.1 Final filling of the system – 126.96.36.199 see’s minor amends in relation to softened water and the need to add corrosion inhibitor specifically formulated for this type of system, in a dosage recommended by the manufacturer.
188.8.131.52 – new Commentary added regarding the compulsory measurement of CO during commissioning process of a new boiler and the additional guidance contained within a Gas Safe Register Technical Bulletin 143.
184.108.40.206 – minor amend to text to “heat input is measure and, where necessary, correctly adjust…” (2009 Standard stated “input is correctly adjusted in accordance…”).
220.127.116.11 & 18.104.22.168 Commentary – minor amends.
8.3 Advice to user of the appliance
8.3.1 User instructions – a new Note inserted on the requirement of the GSIUR for instructions to be left on site with the user.
22.214.171.124 Commentary – text added on the legal requirement for parts of the UK to have CO detector alarms installed.
126.96.36.199 – new text and Commentary inserted on multiple points of electrical isolation and the correct labelling of such systems.
8.3.3 Maintenance – a new paragraph inserted to Commentary advising that older CO detector alarms (those manufactured to BS 7860) installed on existing installations should be replaced for a CO detector alarm that complies with the latest requirements of BS EN 50291.
8.4 Service & maintenance
1st paragraph amended to be a new Note 1 on the need to use competent persons (Gas Safe Registered engineers) for servicing/maintenance procedures.
Note 2 amended with regards to demonstrating competence in the use of combustion gas analysers.
Annex A (normative) Connection options for condensate and combined pressure relief valve/condensate discharge
Text and Figures moved from body of document in 2009 Standard to form a new Annex A.
A.2 Connection to an external foul water discharge point – new text formed from industry guidance published by the Heating and Hotwater Industry Council (HHIC) on preventing condensate arrangements from freezing.
Figures A.2 a) & b) amended to reflect the requirement for increased pipe diameter for pipe passing to external atmosphere, inclusion of insulation material, point of termination cut at a 45° angle, etc.
A2.3 Connection to an external soil and vent stack system – text largely unchanged (slight amends), but moved to appear after Figure A.2 b).
A2.4 Connection to an external drain, gully or rainwater hopper (Figure A.4) – 2009 Note 1 & 2 deleted; Note 1 was a cross reference and Note 2 discussed pipe entry on rainwater downpipes.
New Figure A.3 Connection to condensate drainage pipe to external soil and vent stack.
Amended Figure A.4 (2009, Figure 3) External drain, gully or rainwater hopper – increased pipe diameter for pipe passing to external atmosphere, inclusion of insulation material, point of termination cut at a 45° angle, etc.
A2.5 Special conditions when using a rainwater downpipe (Figure A.5) – new text and Figure A.5 on the requirements of using this condensate termination arrangement.
A2.6 Connection to a purpose-made soakaway (Figure A.6) – amended Figure A.6 to reflect the requirement for increased pipe diameter for pipe passing to external atmosphere, inclusion of insulation material, point of termination cut at a 45° angle, etc.
As can be seen, the Standard has undergone significant review/amends with the greatest amends relating to condensate discharge/disposal. Read as a whole, the revised BS 6798: 2014 introduces advancements in safety and satisfactory operation of installed condensing boilers, and as such can only be welcomed as an improvement over the withdrawn 2009 Standard.
Ensure your up to speed on the latest requirements of BS 6798: 2014.