ACS - Core Domestic Natural Gas Safety (CCN1) and Appliances (CORE + appliances)Reassessment

Who is it suitable for?

The ACS re-assessment is for existing gas professionals who already hold, or have held (certification expiry must not exceed 12 months to qualify for re-assessment, if this period has passed the initial assessment must be undertaken) the ACS Core Gas Safety domestic qualification and relevant gas appliances. 

Course programme

The candidate will be assessed in the following areas:-

  • Gas safety legislation and standards.
  • Gas emergency actions and procedures
  • Products and characteristics of combustion (including combustion performance analysis)
  • Ventilation
  • Installation of pipework and fittings
  • Tightness testing and purging
  • Checking and/or setting meter regulators
  • Unsafe situations
  • Emergency notices and warning labels
  • Operation and positioning of emergency isolation controls and valves
  • Checking and setting appliance burner pressures and gas rates
  • Operation and checking of appliance gas safety devices and controls
  • Chimney Standards
  • Chimney inspection and testing
  • Installation of open balanced and fan assisted chimneys
  • Re-establish existing gas supply and relight appliances
  • Inspect, test, commission and maintain gas appliances 


Gas appliances that can be renewed at Moor Training include Boilers (CENWAT), Cookers (CKR1), Fires (HTR1), Smart Meter Installer Core (CMA1/3) and Meters (MET1). Liquid Petroleum Gas (LPG) within Permanent Dwellings (PD), Residential Park Homes (RPD) or Leisure Accommodation Vehicles (LAV).


The domestic gas safety relates to ‘domestic’ natural gas installations, with:

  • Maximum Operating Pressure (MOP) at the outlet of the ECV of 2 bar (medium pressure)
  • Operating pressure at the outlet of the gas meter of nominally 21 mbar (low pressure)
  • Gas pipework maximum bore of 35 mm (DN32, R 1¼)
  • Maximum Installation Volume (IV) of 0.035 m³
  • Maximum rated capacity through the primary meter of 16 m³/h and
  • Gas appliances having a maximum individual heat input of no greater then 70 kW net.

If the scope worked on is above that listed, this course is not suitable. Working on gas exceeding this must be undertaken via a commercial course. Undertaking without a commercial qualification/Gas Safe registration is illegal.



5 years. Candidates can undertake the re-assessment of any element up to 6 months early without losing any time (MOT Style). Previous certificates must be produced at the time of assessment as evidence. 


3-4 days


£600.00 (+VAT) inclusive of training material and certification

Entry Requirements

For re-assessment candidates must have held the element previously.

Up to 6 months early without losing any time (MOT Style).

If held previously certification expiry must not exceed 12 months . If this period has passed the initial assessment must be undertaken.

Previous certificates must be produced at the time of assessment as evidence. 

Delivery Method

½ days training and approximately 3 days assessments.

For assessment only (no training) please contact the centre direct. 


Assessment is carried out using a variety of assessment methods including multiple choice, short written response and scenario questions and observed practical assessment.


CALL US01837 659357



With purpose-built workshops and experienced tutors, Moor Training will prepare you for a long and lucrative career in plumbing and gas installation.


  • Free & Secure parking
  • Modern, purpose-built, well equipped centre
  • Industry recognised, premium quality training
  • Express certification
  • Sociable, friendly atmosphere
  • Knowledgeable staff providing reassurance and great customer service
  • Apprenticeships with job opportunities throughout the South West 


Ask one of our team
call 01837 659357