Found this one in Coldstream, Ontario and another in Arva, Ontario. They are within the same township. Looks like a European siren or just a vent. Maybe a Model 3?
Coldstream:
http://maps.google.com/maps?f=q&hl=en&g ... 3,,0,-1.56
Arva:
http://maps.google.com/maps?f=q&hl=en&g ... 96,,0,6.05