New Fridge

[tabbycat09]

I have recently had a new fridge installed. I was given conflicting advice about how long to wait for switching it on. Engineer who did the installation advised leaving it for 6 hours, but the manual advised 8 hours. I switched it on after six hours. Consequently it is very noisy and rattly. Although it is doing it's job ok in that the ice box is sub zero and the fridge temperature is Ok. Are new fridges normally this noisy or could I have caused dome damage by switching it on be3fore the ieght hours.