The fan should be mounted as far forward as possible to keep it from being
cooked by the outlet heat from the heaterboxes.  A good installation spot
would be over the spare tire (but be advised that it will not supply the
floor vent in the step at the back edge of the drivers' compartment if
mounted at that point in the duct).
  Note that in any case, the fan and motor will be operating above their
design temperature, and service life may be measured in months (the fan blade
melts and the motor's permanent magnets lose their magnetism).  I would
suggest using quick-disconnect connectors (such as spade lug connectors) and
keeping a spare fan unit on hand with matching connectors to enable a quick
replacment if needed.
  Recirculation presents a slight problem, in that after shutdown the hot air
from the heat exchangers will flow back up into the cabin through the
recirculation intake duct -- great in winter, not so good in summer.  A
spring-loaded or counterbalanced door is needed in the duct to keep the air
from flowing back into the cabin, and if you seal the heaterbox intake
completely, there is a possiblity of damaging the heaterboxes from uneven
cooling.
  One possibility for a _partial_ recirculation system would be to run a duct
from under the back seat to a tee connection with the crossover pipe between
the stock blower and left heaterbox, while leaving the remainder of the
system intact.  Feed it with an inline blower such as the one you have
already (the crossover tube is approximately 3" dia, so you'll need to step
the duct size down somewhere along the way) and include a anti-backflow door
as mentioned above.  Put the door between the fan and the duct to prolong the
life of the fan.
  That's what I'm planning to do with my van this winter, anyhow, if fiddling
with the cables and flaps doesn't result in sufficient heat.

Rusty
Ogden, UT
'80 Westy -- The VW Campmobile Formerly Known As Vanagon Valdiz (sp)

In a message dated 10/24/02 5:47:08 PM Mountain Daylight Time,
CTTAPER@AOL.COM writes:

<snip>
 the inline fan but not
> sure
>  where to mount it and if I should hot wire it off the battery using a fuse
> of
>  course or go through the fuse box? Also to make it a recurculating system
do
>  I take off the rubber elbow at the alternator and run a hose to the
interior
>  back to the plastic cage?  Would the cause the alternator to run hot?
>  TIA
>  Kevin
>  80 Westy