u/Maleficent-Music3249

Got a glowworm combi boiler, installed last year.

Recently I've suspected a gas smell when it's been running for a while, especially when the heating is on. so I called the company who fitted it to check it out.

They checked the meter and the boiler and said all is fine, so I switched it back on.

I bought a gas detector pen type device (tested it was working on my bbq) and the next day, I thought I smelled gas again so I used the pen.

It started beeping, showing 1/5 on the pen (5 being the strongest concentration)

I'm 100 percent sure this is not right, but why would the gas engineer say there is no issue? What did they miss? Obviously I'm going to call them back.