Hi Neil,

Couple of problems with the idea.  First, you're starting with heat
exchangers that are designed for heating air, and will not be very
effective at heat transfer to a fluid filled tube.  Insulation of the
heater boxes will not address the primary issue, which is heat
*transfer*, and heat transfer *rate*.  Yes, if you had "perfect"
insulation, all the heat in the box would end up raising the temp of the
fluid tubes, but without proper surface contact, you are severly
rate-limited in heat transfer rate.  You'd also have to bond the tubing
to the surface (keeping in mind that by design, the *entire* surface of
the heater 'box' is part of the metal->air transfer medium, thus using
less surface area reduces effectiveness) of the heater box with some
sort of thermal conductive material, minimize the cross-sectional area
of the tubing (why radiator tubes are not round), and optimize the fluid
flow rate.  Basically, you're creating a second heat exchange process
that must, by definition, decrease the overall system effectiveness.

Put a fan on the heater boxes, like VW did in the late '70s, to maximize
the heating capability of the stock exchangers.

Keith Hughes
'86 Westy Tiico (Marvin)

>Date:    Sun, 4 Feb 2007 18:22:36 -0800
>From:    neil <musomuso@GMAIL.COM>
>Subject: Air cooled heater idea/questions
>
>Hi all.
>
>BION (believe it or not) I have an actual Vanagon question.
>
>On a 2L AC engine. An idea that's been on my mind.
>
>How crazy is this:
>
>Open up heater boxes,
>
>wind 3/8" or 1/2" soft copper pipe around each exhaust pipe,
>
>assemble/install boxes, (plug hot air outlets)
>
>connect copper coils to create a circuit
>
>install pump, heater core, etc.,
>
>run coolant through to provide interior heat?
>
>Other parts would include an expansion tank, fan etc. Likely the
>biggest cost would be the pump.
>
>Hard to answer, but would there be enough heated coolant present in
>system to provide any appreciable amount of heat?
>
>Purely hypothetical, though i do have 2 spare heater boxes.......
>
>Likely someone has tried this before, but I am curious.
>
>
>
>Pax,
>
>
>
>
>