Gas Lessons
Explore step-by-step lessons covering key gas topics for UK engineers and students. Work through the fundamentals in order, or jump straight to appliance and fault-finding lessons when you're ready.
Switch between lesson content and matching exam-style question sets.
Unlock All Gas Lessons
You can work through the first fundamental lesson for free. To unlock all 19 gas topics and every micro-lesson, choose either the Lessons-only plan or the full GasTheory Pro plan with lessons and questions.
Tip: search inside lesson text too (e.g. “combi”, “mbar”, “tightness”).
Fundamentals (Track A)
Regulations & Acts
Key UK gas legislation and acts, including duties of employers, employees and landlords.
Combustion, Measurement & Testing
Combustion principles, products of combustion and using flue gas analysers to assess appliance safety.
Gas Controls
Types of gas controls and safety devices and how they protect the appliance and installation.
Chimneys & Flues (Open & Room-Sealed)
Requirements for chimneys and flues, terminal positions and testing flue performance for different appliance types.
Ventilation
Ventilation requirements, free area calculations and room sizing for different gas appliances.
Measurement of Gas Pressure & Tightness Testing
Standing and working pressure checks plus tightness testing of low-pressure gas installations.
Re-Establish Gas Supplies (Purging after Testing)
Safe procedures for restoring gas supplies, purging air from pipework and bringing appliances back into service.
Pipe Sizing & Low Pressure
Sizing low-pressure pipework, pressure drop, diversity and good layout practice for domestic installations.
Checking & Setting Burner Pressure & Gas Rates
Clocking the meter, confirming gas rates and adjusting burner pressure to manufacturer requirements.
Appliances (Track B)
Pipework Installation & Fittings
Installing copper, steel and plastic pipework, jointing methods and support requirements.
Low-Pressure Meter Installations
Types of low-pressure meters, siting, bypass arrangements and associated controls.
Statutory Requirements & Unsafe Situations
Recognising ID, AR and NCS situations and applying the Gas Industry Unsafe Situations Procedure.
Central Heating Systems
System types, controls, basic hydraulics and common issues on domestic heating systems.
Space Heaters
Open-flued, balanced flue and flueless space heaters and their installation requirements.
Gas Cookers
Siting, connection methods, stability requirements and common safety checks for cookers.
Warm Air Heaters
Operation and installation considerations for domestic warm air heating units.
Water Heaters & Combination Boilers
Storage and instantaneous water heaters plus combi boilers and their specific checks.
Tumble Dryers & Other Appliances
Gas tumble dryers and less common appliances, including flueing and ventilation needs.
Fault-Finding: Fan-Flued Combi Boilers
Typical faults, diagnostic approach and safe isolation when working on fan-flued combi boilers.