Hi Martha, thankyou for your link, works perfectly :D. our ventilation units were the ones on roof of the building, not the apartment so we couldnt shut them off, like a hair dryer going off all night. I thought it was mrs D at first regurgatating a cockroach swalllowed in pool

One night we heard an almighty crash and thought one of the kids had fell out of bed, mrs D ran into lounge to check which one had the fractured skull, dad didn't..... takes me a while to come round

and the mystery was solved when we learned there had been an earthquake during the night. the infamous ventilation unit had collapsed on its side. can't wait for this september.............