I got one like this from ebay:
http://www.ebay.com/itm/Broan-roof-cap-vented-range-hood-/330353950497?pt=LH_DefaultDomain_0&hash=item4ceaa13f21I've tried the plastic vents & even with a long bit of flexi hose between the heater & vent they still eventually melted, so metal is essential IMO. I removed the hinged flap inside my vent as its intended for heaters with a forced exhaust fan, which the fogwash doesn't have.
To cut through the roof, first protect the area with duct tape for about 3" all around the hole (this will stop paintwork getting scratched) then drill a hole with a 10mm metal bit as a starting point for cutting with a jigsaw. Use a fine metal blade on the jigsaw, take it slowly & carefully to get a neat cut. When finished cutting, remove the duct tape, file off the sharp edges, and paint the bare metal edge with a rust proofing paint.
The vent has bolt holes in, so mark & drill these (again, use duct tape & paint the edges after to protect from rust) but remember when you're fitting not to over tighten the bolts.
I used a SIKA brand sealant to fix mine,.. its expensive but MUCH tougher than standard silicone sealant. You can also use windscreen adhesive which comes in the same kind of tube & is available in most motor factors. The sealant can be used to fill the gaps dues to the ridges in your van roof.
Right, I've decided I need my fogwash vented through the roof. Up 'till now I've worked with the side door open. I've also forgotten the side door was open and started to drive off only to lose the makeshift flue on the way. Not only that I've forgotten to open the side door, worked from the back door forgetting all about the heater and it's fired up quite happily inside the van - not good. Also because I don't turn my varistream off between jobs, should the pressure drop for any reason then the heater will fire up again when the water flow comes on.
1) where can I get the cowling
2) metal or plastic
3) best tool to cut through the roof
4) how to adapt any vent to the ridges in my roof should it be required? Mastic of some kind or fireproof sealant like they use in exhaust systems or what?
Nat, are you here yet?
Pictures if possible please
Wonder what the company uses who fit their own similar heater?