Be Alarmed

Be alarmed

CO Positioning TN 0022The positioning of a carbon monoxide alarms can be an important factor in ensuring compliance with Approved Document J and ensuring an alarm has the best opportunity to identify carbon monoxide. HETAS Technical Note 0022 has all the information you need.

Questions from installers over the type, suitability and positioning of carbon monoxide alarms continue to be a regular occurrence on the HETAS technical helpline. There is confusion caused by differing guidance and advice on suitable positioning given within UK Building Regulation approved documents and CO alarm manufacturer installation instructions. When installed, operated and maintained correctly, instances of solid fuel appliance CO spillage are rare, nonetheless the Building Regulations still require all new or replacement solid fuel appliance installations to permanently affix a CO alarm in the room in which the appliance is located. Improper selection and location of an alarm may result in CO detection being limited, leading to an increase in the time taken for CO activation upon spillage occurring and decrease in time available for occupants to vacate the building safely.

What do the Building Regulations Say?

Approved Document J of the Building Regulations lays out the statutory requirements for installations of solid fuel appliances. In particular regulation J3 states the following:

Warning of Release of Carbon Monoxide

J3. Where a fixed combustion appliance is provided, appropriate provision shall be made to detect and give warning of the release of carbon monoxide.

 The regulations are clear in laying out the conditions for ensuring a CO alarm compliant with BS EN 50291 is present upon installation of a solid fuel appliance, however establishing the suitable type, position and fixing method is where confusion can exist between current appropriate standards and alarm manufacturers’ installation instructions.

Supplementary Information on Selection & Positioning

As well as the statutory requirements detailed on page9 of ADJ, further information can be found within:

  • Clause 2.34 to 2.36 of Approved Document J
  • Supplementary product and installation standards including BS EN 50292 & BS 8303
  • Alarm Manufacturer Instructions

Although the regulations simply require appropriate provision to be made, it is important for the general safety of the occupants that installers and landlords are selecting and positioning an alarm effectively allowing the quickest response time from the alarm for the occupants to vacate the premises. This document details some of the best practice considerations and should be followed as closely as possible It is worth noting that manufacturers who supply alarms do so for a number of different technology types, so guidance provided may cover suitable provisions for a range of appliances.

Best Practice

Confusion around the appropriate selection and positioning of a CO alarm normally comes about where the installer or landlord are being provided conflicting advice from a variety of sources. It is important for the installer or landlord to understand the behaviour of CO emissions to assess in practice the best location of the alarm. In principle, CO has almost the same density as air and would be emitted as part of spillage of combustion products which are hot and will warm the air around the appliance. This warmer air is likely to rise due to its buoyant characteristics, which supports best practice measures and those given within regulatory guideline in positioning the CO alarm at a high position on the wall or on the ceiling.

Whilst complying with J3 of the Building Regulations, it is important to ensure the CO alarm is of a suitable type and positioned in a suitable location as to provide the best warning of CO upon spillage. The referenced provisions below allow for the installer/landlord to competently enforce best practice on the selection and positioning within a room containing a solid fuel appliance.

Product Selection – Alarm Type

A suitable alarm will have been tested to confirm it meets the necessary requirements of BS EN 50291:2010, and activate within the required time when the relevant volume of CO is detected. The alarm packaging itself will contain the relevant information, including appropriate Kitemark reference (if tested by BSI) and also confirmation of the test method standard, warning of the expected lifetime of the sensor and where incorporated stating the product includes an end of life indication.

Sealed for life vs Replaceable

There are currently three known types of alarm on the market, which are:

  • Sealed for Life: Alarms that have a fixed, sealed power source which will require complete replacement once the end of life which is normally a minimum of 5 years
  • Replaceable battery: Alarms that have a replaceable power source
  • Mains powered: Alarms normally powered by wired mains electricity but containing a back-up battery for mains failure events

It is important to note that any of these three types of CO alarm are suitable for use with solid fuel installations. If they have been confirmed as meeting the requirements of BS EN 50291 then they shall incorporate a warning device to alert users when the working life of the alarm is coming to an end. It is important for any installer landlord to ensure that they educate the consumer in knowing what action to take when the alarm sounds, and that the end-of- life warning means the unit or battery will need to be replaced and new alarm tested immediately. Landlords and installers can further educate the consumer or tenant by ensuring a test of the operation of the alarm is undertaken on a regular basis.

All manufacturer’s alarms compliant with BS EN 50291 will contain a “test button” which when pressed will sound an audible alarm and flash its LEDs to show that the alarm is correctly operating.

Alarm Positioning

The general provisions within ADJ and BS8303 ask that the CO alarm be positioned in a location which provides means for the immediate detection of CO upon spillage from a solid fuel appliance. Guidance in ADJ and in BS8303 is that CO alarms should be positioned as follows;

  1. a) On the ceiling at least 300mm from any wall or, if it is located on a wall as high up as possible (above any doors or windows) but not within 150mm of the celling; and
  1. b) Between 1m and 3m horizontally from the appliance

These stated parameters allow for the earliest possible detection of CO as the combustion products disperse and mix with the air within the room. In these positions the detector is also avoiding the relevant “dead zone” areas whereby the velocity of gases disperse and convect in a circular motion and do not reach the corner areas of the room. It is also important to ensure CO alarms are not located directly next to the appliance, or within areas where air disperses at a slower rate. Typically installations of solid fuel appliances are within a builder’s recess, where the flue is contained within a masonry chimney stack which protrudes slightly into the room in which the appliance is installed. Following best practice, it is also recommended for CO alarms not to be located on the side wall of the masonry stack, which again acts as a potential “dead zone”, which may increase the activation response time of the alarm as the CO disperses into the room in a radiant motion.

Be Alarmed | Carbon monoxide guidance from HETAS

Landlord Requirements

Since the 1st October 2015, regulations now require landlords in England to ensure a co alarm is fitted in any room containing a solid fuel appliance within rented residential accommodation. This applies to both new and existing installations and failure to follow the new legislation can lead to a civil penalty being imposed on the landlord, whose responsibility it is to ensure compliance. Regulations in Scotland and Northern Ireland require similar CO alarm provision. Landlords will be required to check the condition and operation of the alarm at the beginning of each tenancy, however the regulations do not provide information of the placement of alarms, only that the landlord follows the provided guidance within Building Regulations, standards and CO alarm manufacturer’s instructions.

Affixing the Alarm

The regulations currently state that “appropriate provision shall be made to detect and give warning of the release of CO”. Having checked with the Government department responsible, we can state that “appropriate provision” is seen as permanently affixing a suitable alarm to the wall/ceiling in an appropriate place, and that simply leaving an alarm with a customer is not seen as “appropriate provision”. It is vital for the installer to educate the consumer in the importance of the alarm, its position and what to do when the alarm sounds. This document can be used as evidence of the things to be considered and the reasoning behind the requirements. This important information can be relayed to the consumer as part of the commission and handover process.

Further Information

HETAS currently work closely with the Council of Gas Detection and Environmental Monitoring (CoGDEM) in ensuring continued safety in the operation and use of all solid fuel burning appliances. Further information and support on CO alarm requirements can be obtained from the HETAS Technical Helpline on 01684 278194 or by contacting the CoGDEM CO helpline on 0800 1694 457.


Have your say

Installation Sub-Committee | Have your say……Have Your Say

Last month we introduced the newly formed Installation sub-committee which will support the HETAS Technical Committee. To support this group we want you to have your say, starting with Approved Document J.

 In support of the work within this group and to drive the focus of the work we are asking HETAS registrants for their views on Approved Document J.

What are the three things you would like to change in Approved Document J? What doesn’t make sense, what is confusing or unnecessary? HETAS will collate the top answers back to the sub-committee with the intention of working on solutions and a push for change for the better.

As an industry we have a stronger voice when working together and we really want to hear your thoughts on this issue. Through our newsletters and bulletins we will update you on the work of the installation sub-committee and the wider standards work that HETAS undertakes for industry.

Please complete the suggestion form below with your three ideas and we will work through the most popular answers in our next meeting.

We are always looking for installers who are interested in attending the installation sub-committee meetings. If you would be interested in attending or contributing to such working groups get in touch with

Working with Building Control

Working with Building Control (Appendix A) as part of Approved Document J

A recent roundtable hosted by HETAS revealed a number of issues that are affecting both the biomass and wood-burning stoves markets. One of the key areas of discussion was the issues surrounding the ‘signing off’ or ‘notification’ of solid fuel & biomass installations and the evident confusion over a HETAS installer’s role in assisting Building Control to sign off a job as being compliant to Building Regulations.

When looking to buy a home or secure buildings insurance for example, it is important to note that that existing installations must have been notified to Local Authority Building Control by the homeowner or by the builder/ installer concerned.  This notification, or lack of to some degree, is being recognised as an area of concern which needs legislation and enforcing. The subject was discussed recently at a Government meeting. Those present including the Technical Director of Local Authority Building Control (LABC) and the relevant person from the Ministry of House, Communities and Local Government. As this is a matter that effects all areas where self-certification is an option, MHCLG subsequently wrote to the CEO’s of all Local Authorities.

Mike Harvey, Training and Technical Manager at HETAS says, “If an installer is a registrant of a competent person self-certification scheme like HETAS, and the work undertaken is within their categories of competence, then they will notify through their scheme. However if the work undertaken by the installer is not within their recorded competence at the scheme, they cannot notify through their scheme. The only option is to go through Building Control at the local authority or in some cases via an approved inspector.”

HETAS acknowledges the wide range of skills that Building Control Officers have and the necessity for their continuous professional development. An increasing number of Local Authorities have taken the view that solid fuel and biomass training covering requirements within Approved Document J, its interaction with Approved Document F, other Approved Documents and associated Standards would be needed; upon taking this into consideration they have decided that this area of work would be best dealt with by people with specialist training and equipment.

Mike says, “Where a Building Control Officer is unsure about the safety or compliance of a job, he/she might ask for supporting information from a HETAS registered installer. It is likely that the registered installer would say that they cannot sign off the work of another person. In cases such as these the installer would not be ‘signing off an installation’.

“There is a caution in that neither a HETAS Registrant nor a Building Control Officer can definitively appraise some areas of the work undertaken e.g. around the outside of the chimney liner or in places where there is no real access. Consequently the Building Control Officer would be asking the HETAS Registrant for their best endeavours, ensuring appropriate testing where practical so that he/she can advise the Building Control Officer.

“The HETAS installer would be simply checking as much as they reasonably can maybe visually, plus perhaps flue draft, smoke test or whatever is appropriate and advising the Building Control Officer of their findings.”

“It is then for the Building Control Officer to make a decision based on their own skills and experience, plus the supplementary information supplied by the installer.”

“This combination of skills and checks is considered to be a robust way to address the situation.”

Mike adds, “HETAS has not been involved in discussion about who bears the cost of such an inspection but it seems reasonable that the person having the work done might be responsible.  Things are of course much clearer and simpler when a HETAS registrant undertakes the work and self-certificates to HETAS.”

“Should a Building Control Officer ask for assistance from a HETAS qualified installer to carry out an inspection to ascertain compliance they should use the form stated in Appendix A on page 70 of Approved Document J,  because, ultimately the BCO is signing the job off and not the HETAS installer.”

“Indeed, not all of our registrants will remember that HETAS have an agreement with Local Authority Building Control permitting them to assist a Building Control Officer. Anyone seeking clarity or experiencing difficulties engaging help and support should contact HETAS technical helpline.”

“Installers are aware that whilst the space to fit an appliance is often limited – determined by the shape of the room or location of the chimney breast – there are other factors that must be considered to ensure that the appliance adheres to Part J of Building Regulations.”

“This section of Building Regulations, which outlines requirements for combustion appliances and fuel storage systems, is often referenced during our helpline conversations. For example, questions around the use of Chimneys and flues relate to the requirements for discharge of products of combustion (J2) and protection of building (J4). These regulations and other relevant guidance including manufacturer’s instructions serve to ensure that products are installed compliantly, assuring end users in the use of the installation”.

“It’s great to see our installers are paying such close attention to these requirements and  taking them seriously by phoning for advice if the requirements are not clear for them,” says Mike.

HETAS is proud to have the support from various sectors and organisations in the industry. Working alongside influential organisations such as BFCMASFA and the SIA allows the technical team to provide the most up-to-date information and educated advice.

“Ultimately our aim is to be recognised as the go-to resource for any domestic heating related queries so that we can continue to encourage the improvement of products and promote high standards of quality, design, safety and efficiency.”

Contact the HETAS Technical Helpline to discuss this further, or call 01684 278194.

Flue size update

doc_jIn October 2010 our Technical and Training Manager Andy Mathews issued an update on flue sizes, the issues highlighted by Andy remain prominent and can be read below. Andy writes: Through the ongoing HETAS inspections process we are realising that there are a number of installations that are failing in respect of the flue installation. One of the more common areas of non compliance has been recognised by our inspectors and these concern flue sizes and those associated flue connection arrangements. It has been observed that 125mm flues have been fitted instead of the required 150 mm flues. There is clear evidence in failure to observe the appropriate Building Regulations in force controlling the installation of flue liners.

All appliances up to 30kW

The Building Regulations 2010 state that appliances burning any fuel and rated up to 30kw would require a minimum 150mm diameter flue liner. The Building Regulations are more stringent than manufacturers’ instructions; therefore, the Building Regulations must be abided by unless the manufacturers’ installation instructions state a larger diameter. The quoted flue liner size should be as per manufacturer’s instructions but in all cases should be at least 150 mm diameter or larger where appropriate. The following extract confirms this: The Building Regulations (2010) Approved Document J: page 30, 2.6, that “For multi-fuelled appliances, the flue should be sized to accommodate burning the fuel that requires the largest flue.”

Smokeless Fuelled Appliances: and Defra exempted Appliances up to 20kW rated output

A DEFRA exempted appliance is one that meets the standard for burning non-authorised fuels in accordance to the Clean Air Act. The Building Regulations, Approved Document J, Table 2, suggest you may line the chimney with a 125 mm diameter liner for burning only authorised smokeless fuels or the fitting of an exempted appliance burning one of the fuels listed in the exemption record for that appliance. This assumes that the appliance manufacturer does not specify a
larger diameter flue is required.

Note: This is not to be confused with connecting flue pipes, where the connecting flue pipe should have the same cross sectional area as that of the appliance flue outlet, and should not be smaller than the size recommended by the appliance manufacturer. Where possible the Connecting flue pipe should be kept to the shortest practical length.

Registered installers should also refer to Chapter 11 of the HETAS Technical Handbook.

Andy Mathews
Technical and Training Manager

Heat Producing Appliance Ventilation

Heat Producing Appliance Ventilation

Rytons Building Products have released the following update on ventilation for heat producing appliances, the article can be found on the Rytons website by clicking here.

In October 2010 the Building Regulations Part J changed – but some manufacturers still have not. The changes meant all ventilators for heat producing appliances should be tested by an accredited independent company for equivalent area. This is the air that actually passes through the product not (as previously) geometrical free area which is simply the measurement of the most restricted openings. The old style of measurement was felt to be less accurate due to the more modern designs of ventilator which tend to incorporate changes in shape, complex baffles and cowls which limit performance (air that can pass through).







If you look at the image above it’s easy to appreciate how simply measuring the gaps between the baffles would not be a true reflection of how much air actually flows through the vent as a complete system.  That’s why it’s so important to purchase products which declare an equivalent area.

Being at the forefront of ventilation we realised this was the safest and most accurate way to measure airflow many years ago and have been publishing only equivalent areas for our boiler, stove and fire ventilators for over a decade.

Rytons are currently the only manufacturer to have products approved by HETAS and the BBA.  We also have our own on-site testing facility for research and development of our products before sending them away for independent testing. Next time you go to purchase a ventilator for a fire, boiler or stove ask for the equivalent area to ensure you comply with current Building Regulations.

To view all the permanent ventilators in the HETAS Guide click here.

Rytons Heat Producing Appliance Ventilation Brochure is available to download by clicking here. For orders and enquiries contact 01536 511874.