Have him equal times tested the smoke, the value increases until it extremely begins to beep loudly.
Had it really missed once the smoke came from the chimney and it is about 2 meters away. At one time it beeped and we saw how actually smoke in the room was, as a wood only had puff away.
One point deduction I give because it once in the morning went off at 6, although no fire was. I do not know whether it was a test, but it was a value indicated ?! Was strange. But rather than the other way so ...
