Northampton · West Northamptonshire
What the Engineer Checks During a CP12
Knowing the inspection contents makes you a better buyer of it — and helps you spot a rushed or fake certificate.
The statutory checks
Per the Gas Safety (Installation and Use) Regulations 1998 and Gas Safe technical guidance:
1. Flues and chimneys: route, support, termination, and a flue flow test — combustion products must clear the property. 2. Spillage test: with the appliance running, detect whether products of combustion spill back into the room. 3. Gas rate: the appliance burns at its designed rate (measures input against manufacturer data). 4. Working pressure / standing pressure: supply pressure at the appliance and at the meter. 5. Safety devices: flame supervision devices, overheat cut-outs, thermostats — each proven to operate. 6. Ventilation: permanent ventilation provision is present and correctly sized (blocked air bricks are a common ID finding). 7. Visual inspection: appliance supports, pipework condition and labelling, flue termination positions relative to openings. 8. Appliance-by-appliance verdict: for every gas appliance in scope — boiler, fire, cooker, water heater.
The paperwork you receive
The Landlord Gas Safety Record must show: date, property address, engineer name + Gas Safe number, appliances/flues checked, results, defects and remedial action. Verify the engineer's number on the Gas Safe Register — an engineer not on the register cannot issue a valid record, and using one leaves you in breach.
Red flags of a junk certificate
- No individual appliance results (one tick for the whole house).
- The engineer never ran a flue flow or spillage test (takes minutes; impossible to fake properly).
- No Gas Safe number, or a number that doesn't match the ID card.
- "Issued" without a visit — a criminal fraud with you as the named beneficiary.