With the dangers of carbon monoxide well advertised, consumers are advised to minimise the risk of exposure by ensuring that all gas appliances and flues within their household are regularly maintained and all ventilators are clear. Fitting an audible CO alarm is also highly recommended and therefore trained gas engineers are required to deal with the leak in the event of an alarm going off.

Where signs of CO have been reported or an alarm has activated, a detailed examination of the gas appliances installed within the property will need to be carried out in accordance with the guidance and procedures detailed in BS7967. The ACS assessment, CMDDA1, has been introduced to assess the competence of the gas engineer to carry out this detailed examination and determine the cause of the CO.

What carbon monoxide appliance testing covers
CMDDA1 is limited to responding to reports of CO from domestic gas appliances.

If there has been an incident where the occupier has been taken to hospital or a fatality has occurred from suspected CO poisoning, the requirements of The Reporting of Injuries, Diseases and Dangerous Occurrence Regulations 1995 (RIDDOR) apply. In this instance, the gas installation must not be disturbed, only made safe e.g. cap the gas supply at the meter. CMDDA1 does not cover the competencies required to carry out investigations in this case.

Pre requisites
The dwelling type will determine what ACS certificates must be held prior to taking CMDDA1. For examples, gas engineers intending to investigate suspect Natural Gas installations in domestic dwellings must hold valid ACS certificates for CCN1 and domestic appliances, plus CPA1 or equivalent gas services N/SVQ. Likewise, where the dwelling uses Liquefied Petroleum Gas (LPG) the appropriate core or changeover and appliances must be held.

CMDDA1 is available as assessment only. It is strongly recommended that gas engineers familiarise themselves with the content, procedures and guidance provided in BS7967, parts 1-4, in preparation.

During the assessment the gas engineer will be provided a series of scenarios where CO in the atmosphere has been reported, they will then carry out a detailed investigation of the gas appliances installed and identify the cause of the CO. The investigation will require the engineer to select the appropriate equipment, carry out a risk assessment, conduct a series of atmosphere sampling tests, confirm the presence of CO and identify the faulty appliance.

Once the presence of CO is confirmed and the suspect appliance identified, the gas engineer will carry out a series of tests including combustion performance analysis and either repair or make safe the faulty appliance. All relevant information, risk assessments, results of atmosphere sampling and appliance tests are recorded on an Incident Report Form.

The assessment also covers the presence of CO in atmosphere by causes other than a gas appliance. Gas engineers will be assessed on their underpinning knowledge of BS7967 by correctly answering a number written multiple choice questions.

For more information and to book the Carbon Monoxide appliance testing course, click here.

Apart from the domestic core assessment, CCN1, and the central heating and hot water assessments, CENWAT (previously CEN1), Cooking Appliance training and assessment, CKR1, remains the most common domestic assessment undertaken by gas engineers with circa 110,000 valid ACS certificates currently held.

Types of appliance

CKR1 covers gas work on all gas cooking appliances, including; free-standing and ‘slide in’ cookers, ‘built in’ hotplates, ‘built in/under’ ovens and grill units, covering; installation, commissioning, exchanging, disconnecting, servicing, attending to breakdowns and repair.

CKR1 in itself does not cover range-type cookers, such as AGAs, due to their specialist nature; this appliance is covered by CKHB1. However, when CKR1 is held with CENWAT and CPA1, the Gas Safe Register will recognise you as competent to work on ranges.

It should be noted that CKR1 does not assess any electrical work. Where a built in oven or hob requires connecting to the electrical installation, by means of a switched spur, this must be carried out by competent electrician and is notifiable to the Local Building Control Office.

Pre-requisites

Like other ACS appliance assessments the type of fuel and dwelling the cooking appliance is located determines what ACS core assessment is required.

If the appliance is installed within a domestic dwelling and is connected to a Natural Gas supply, the engineer must hold a valid CCN1 certificate (or equivalent). CCN1 may also be appropriate where the appliance is installed in a commercial property, depending on the situation. CKR1 can be completed by a commercial gas engineer holding a commercial core, where a cooking appliance is located in a commercial environment e.g. a domestic gas cooker fitted in a pub kitchen. In this case, the catering engineer holding CCCN1 could undertake CKR1 without CCN1.

Note; Gas Safe Register will not issue a Licence card indicating the catering engineer’s competence in domestic cookers, without CCN1.

Where the appliance is located within a dwelling and connected to a LPG supply, CCLP1 (PD) is the appropriate core assessment. Likewise, if the appliance is located in a Residential Park Home or Leisure Accommodation Vehicle or on a Boat, Yacht or other Vessel CCLP1 (RPH), (LAV) or (B) applies.

Note; only cooking appliances specifically designed for use in a marine environment should be installed on Boats.

Taking the assessment

As with all ACS assessments, only matters of gas safety relevant to the appliances type will be assessed.

Where an engineer is undertaking CKR1 for the first time (initial assessment) a typical assessment will require engineers to demonstrate that they can safely carry out the installation and commissioning of a freestanding gas cooker in accordance with the manufactures instructions and British Standards, plus explain its safe operation.  In addition to installation, the assessment may require the engineer to carry out the service of a cooking appliance, identify any installation and gas control which are defects.

The engineer will be required to successfully answer a number of knowledge questions relating to cooking appliance installation and its safe operation.

Where CKR1 is being renewed, the installation element of the assessment, and a number of knowledge questions, are omitted.

CKR1 can be taken as stand alone training and assessment, or as part of the CCN1 gas safety training and appliances package.