Distribution centres and large warehouses have pest problems unlike ordinary buildings: vast floor areas, doors opening constantly, and high racking creating a great many dead corners.

Treating spaces like this requires long continuous run time — some sites need more than an hour and a half per round — which means the machine must genuinely run continuously, not merely start.

And that makes one particular fault a very large problem in such places: running for a while, dying, and refusing to restart until the machine cools — among the hardest faults of all to diagnose.