Regulations · Glossary
G3 Qualification
The Building Regulations Part G3 qualification required to install or service unvented hot water cylinders over 15L.
G3 refers to Building Regulations Approved Document G, Section 3, which governs unvented hot water systems. Anyone installing, servicing or commissioning an unvented cylinder over 15L capacity in England and Wales must hold a current G3 ticket, typically issued by Logic, ACS or BPEC.
The qualification covers: safety devices (T&P relief valve, expansion vessel, pressure reducing valve), discharge pipework (D1 and D2 routing), commissioning checks, and periodic inspection requirements. A breach is a serious safety matter — overpressure failure of an unvented cylinder is potentially explosive.
All CCS heating engineers carry current G3 tickets. We provide annual unvented cylinder service contracts in Cornwall covering safety check, expansion vessel re-pressurisation, and discharge clearance. See our boiler servicing page or call 01209 596 002.