Had a problem at a site where they had limited roof space above a kitchen, canopy was too small and original inline extract fan wasn't up to the job. Replaced it with a biga$$ roof fan and got manufacturers to extend the canopy to where it should be. Sent testing bod down to check all is working proper like......
Testing bod: "I've got a problem with the kitchen canopy, the extract rate sucks."
Me: "Try testing it with the grease filters out"
Testing bod: "Why can I see roof timbers?"