I use plan (b).  Throw the plastic pieces away.  Cover the metal, or plastic in two cases, part of the flap with peel & stick foam tape.  You can get wide variety of thicknesses and widths at any home improvement or hardware store.  I also use a foam tape made for sealing the gap on a truck cap to the edge of the bed where they meet, peel and stick one side.  I/8" ~ 3/16" thickness is good.  Experiment and you will see how the flap seals against the opening.  Not much of the foam ever touches the sealing edge but if it's too thick the flap will not seal properly.

On 2012-12-10, at 5:32 PM, Automatic digest processor <LISTSERV@GERRY.VANAGON.COM> wrote:

> It looks to me like the heater flaps are constructed with a metal base into
> which a plastic rectangle was pressed, the foam seal being held between the
> plastic and the metal (don't know if the foam was stuck to the plastic or
> just held in place by it).  Should I
> 
> (a) leave the plastic there, and stick my foam to the plastic?
> 
> (b) remove the plastic and stick my foam to the metal?
> 
> (c) remove the plastic, put my foam in, stick the plastic back on?

Cheers,    

Frank Condelli
Almonte, Ontario, Canada
'87 VW Westy, '00 Kawasaki 250 Sherpa, "98 Ducati 750 Monster & Lionel Trains (Collection for sale)
Frank Condelli & Associates - Vanagon/Vanagon Westfalia Service in the Ottawa Valley
Vanagon Stainless Steel Exhaust Systems
BusFusion a VW Camper camping event, Almonte, ON, June 06 ~ 09, 2013