Date:         Mon, 5 Feb 2007 10:43:24 -0700
Reply-To:     Keith Hughes <keithahughes@QWEST.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Keith Hughes <keithahughes@QWEST.NET>
Subject:      Re: Air cooled heater idea/questions
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

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,
>
>
>
>
>