Install, service, repair and remove gas fired ducted air heaters

Business Sectors (Suites): Downstream Domestic Gas Installation and Maintenance
Developed by: Energy & Utility Skills
Approved on: 01 Jan 2022


This standard is about working on gas fired ducted air heaters in domestic settings.  Air heaters can be basic warm air units or combined warm area units and can be configured as down-flow, up-flow, horizontal-flow or slot-fit and include open, room-sealed, or fan draught chimneys.

As well as servicing and repairing, this standard covers the work activities of installing and removing gas fired ducted air heaters including when required for new installations or when exchanging, replacing or repositioning gas fired ducted air heaters. It  includes the disconnection, de-commissioning, testing and commissioning that is involved.  It can apply to any type of fuel gas or combinations of fuel gas including, but not restricted to, natural gas, LPG, blended or 100% hydrogen.

This standard should be used in conjunction with:
EUSDSG5 Prepare to work on gas systems or appliances in domestic settings; and
EUSDSG15 Carry out gas tightness testing and check system safety  in small settings.

If applicable, this standard could also be used in conjunction with:
EUSDSG4 Design and size systems for new installations or conversions in domestic settings.

This standard is for gas engineers who work in domestic settings.

Performance criteria

You must be able to:

1. Make sure all required pre-work checks have been carried out prior to starting installation, service, repair or removal activities
2. Carry out all stages of the work in line with installation, maintenance or removal plans or activities
3. Carry out installation, service, repair, test and removal processes in accordance with manufacturers’ specification, industry standards, safety schemes and regulations
4. Carry out installation, service, repair, testing and removal in line with recognised industry practices, work standards, routines and sequences
5. Check that conditions within gas and electricity systems will permit safe de-commissioning and commissioning
6. Use designated safe isolation procedures and warning notices to prevent the unauthorised use of un-commissioned or de-commissioned gas appliances, gas systems, electrical systems and components 
7. Use the correct tools, test equipment and other equipment for each stage of the work being carried out
8. Assemble duct systems and gas and electricity system components to meet requirements of plans
9. Minimise damage to customer property and building features throughout all stages of the work
10. Confirm position of new, replacement or repositioned air heaters meet location, siting and clearances required by manufacturers’ instructions, industry standards’ specification and building regulations
11. Confirm ventilation, return air path and any chimneys for new, replacement or repositioned installations meet industry standards and manufacturers’ instructions
12. Ensure existing systems are clean and free of debris
13. Fix and connect all relevant pipes and components to gas fired ducted air heaters in line with plans
14. Confirm the operation of condensate disposal systems in line with manufacturers’ instructions
15. Use tightness testing and purging, safe isolation and electrical testing procedures to confirm the integrity of systems and appliances
16. Use industry standard checks and testing procedures to confirm the integrity of chimney systems and appliance flue seals
17. Check appliance operating pressure and gas rate meet industry standards and manufacturers’ requirements
18. Use industry standard visual checks and flue gas combustion analysis with approved test equipment to confirm combustion performance 
19. Check gas fired ducted air heaters and systems are balanced, function safely, interact with existing systems and operate in accordance with manufacturers’ instructions
20. Check electrical systems and components function safely and operate in accordance with manufacturers’ instructions
21. Complete and submit all relevant documentation and paperwork in line with industry standards and legislative requirements
22. Instruct property occupiers on the correct operation of appliances and systems and provide them with their copy of appliance literature
23. Resolve problems within own area of responsibility and competence in accordance with approved procedures 
24. Advise of any delays to the work, unresolved problems, unsafe situations and required remedial actions to those who require the information

Knowledge and Understanding

You need to know and understand:

1. Regulations and guidance governing health and safety in the workplace, environmental protection and the use of risk assessments including safe access, working at heights, those relating to substances hazardous to health and building regulations
2. Legislation covering your general responsibilities for your own safety and that of others
3. The limits of your own autonomy and responsibility
4. Gas industry unsafe situations procedures and how to isolate unsafe gas appliances, gas systems and components 
5. Potential hazards that could arise from all de-commissioning, installation, service, repair, removal and commissioning activities and checks to be carried out before work takes place
6. How to access and interpret normative documents, industry standards guidance documents, manufacturers’ instructions, industry standards, safety schemes and regulations
7. Required pre-work checks including operating pressures and volumes 
8. Industry practices, work standards routines and sequences for installing, servicing, repairing, exchanging, replacing, repositioning, testing, connecting, removing, de-commissioning and recommissioning gas fired ducted air heaters and associated systems and components 
9. Types of warm air central heating appliances to ensure correct heater selection including downflow, upflow, horizontal flow, & slot-fit
10. Procedures and work methods for sizing warm air central heating appliances
11. Tests and checks to confirm the suitability of gas combustion performance including the use of approved flue gas analysers
12. Tests and checks to confirm the integrity, suitability, interaction with other systems, performance, operating pressure, gas rate and safe functioning of gas fired ducted air heaters including the use of test equipment
13. Tests and checks to confirm the integrity, suitability and performance of chimneys, ventilation systems and the return air path including natural & fanned air supply
14. Procedures and appropriate test equipment for checking gas fired ducted air heaters performance including pressure, flow rate and temperatures 
15. How to balance gas fired ducted air heating systems
16. How to measure and record installation and site details for prefabrication 
17. The industry practices and work standards for fabricating new or existing duct systems for the installation of warm air central heating appliances, systems and components
18. How to confirm that services and system requirements are adequate for gas system and components
19. Safe isolation methods, tests, and procedures for temporary and permanent de-commissioning of gas and electricity systems, components and appliances including use of temporary continuity bonds, non-contact voltage detectors, voltage indicators, proving units, multimeters
20. Measures to prevent un-commissioned and de-commissioned appliances or systems being brought into operation 
21. Components of gas fired ducted air heaters including warm air ducting, return air ducting, plenums, plenum adaptors, transfer grilles, registers grilles and condensate drains
22. Positioning and fixing requirements for gas fired ducted air heaters and components including in airing cupboards, compartments, roof spaces, slot-fit and under stairs
23. Methods of working which protect building décor, customer property and existing systems and components
24. Safe processes and procedures for applying tightness testing and purging, safe isolation and electrical testing to appliances, gas systems and components to ensure safe functioning
25. How to safely collect and dispose of system contents that may be hazardous to health or the environment
26. The steps to take when problems arise with work activities 
27. Job management structures and methods of reporting and recording job progress or problems delaying progress
28. How to complete documentation and records and which statutory body to submit it to including building regulation self certification
29. System and appliance handover and demonstration procedures


Scope Performance

Scope Knowledge





Links To Other NOS

External Links

Version Number


Indicative Review Date

01 Jan 2025





Originating Organisation

Energy & Utility Skills

Original URN


Relevant Occupations

Domestic Gas Engineers

SOC Code



install, domestic, gas, fired, ducted, heating, installation, gas, energy, utility, utilities, maintain, maintenance, commission, decommission, replace, LPG, blended fuel, 100% hydrogen