Escalation to gas leak detection may not be required.
There may be an issue an experienced plumber can spot in five minutes if he's given the space to look around.
There may well be, (and probably is) an existing internal stoptap, just no-one has looked for it yet.
I think you need to organise a plumber visit with a carer present to calm your mother while the plumber goes about his business.
This is very common in the world of plumbing.
The word "designer" usually means "overpriced c**P" that looks flash online/in the catalogue but is actually pretty rubbish."
Well-engineered or just plain bog standard is generally miles better.
Could have been a touch neater, but any builder /carpenter/kitchen fitter who understands the need to leave ready and unobstructed access under the boiler to valves, filling loop, condensate trap and for other service and repair procedures is a jewel.
The worst thing a visually perfect...
Fair question, how long for your motor run/start capacitor to self-discharge after unpowering.
I don't know.
Perhaps a question for the electricians forum.