[Haggis]

I was on the roof checking the vents and tapped the top of the covers on all vents with the handle of a screw driver and only got a hollow sound from one of them. Took the covers off and three were stuffed with insultion.

I discussed the vents on the roof with the factory the last time I was there and was told there is only one vent and this services both black and gray tanks. The others with vents covers provide access and are stuffed with insulation until such times as when it will be needed for wiring such things as solar panels, satelite, etc.