Grumps wrote:

Just about to buy a cooker with a gas hob. We currently have an
all-electric one. There is a gas pipe bayonet thingy behind our cooker,
but it hasn't been used in over 15 years (maybe never). Is there anything
that might need attention before we try to attach the new cooker? Clean,
lubricate, etc. Ta.

Check/clean bayonet, make sure socket is facing downwards and pipework
properly supported.

Check ventilation for cooker is OK (IIRC the spec is in the building regs).

Make sure clearances around and level of cooker are OK (ditto).

Check/fit stability device (chain or L-bracket).

Fit hose to cooker using appropriate sealant (e.g. Boss white, or gas-type
PTFE applied in the correct way). Make sure hose will hang freely and not
subject to damage in any way.

Pressure-drop test gas installation to make sure bayonet connection is OK
and cooker doesn't leak internally.

Check cooker works OK (manufacturer's installation/commissioning
instructions should give procedure). For a hob it'll basically be that the
controls work OK, flames look OK at all settings and don't go out or
noticeably affected (can check working pressure to confirm) with
newly-installed combi running at full hot-water flow at the same time. If
there's a hob lid check that gas goes off and flames go out when lid is
lowered.