At 09:11 12/30/99 , George Jannini wrote:
>    Dan, (and Todd), the green LED should work in both 12 volt and propane
>operation.  It does not light in the 110volt mode.  In my experience, the

Well...the green light is *supposed* to indicate that the flame is
on.  Because the VW  (ground) wiring is marginal, and most especially if
the ground connection isn't perfect, it also tends to light up when the 12v
is running.  However, that is an artifact and ought to be curable by
perfecting the ground and increasing the wire size.  That would also
improve performance on 12v.  Increasing the supply wire size as well should
improve performance even more, possibly dramatically.

Which reminds me, a reason I don't see commonly mentioned for the 12v mode
to be less effective than 110v mode is that small resistances in the supply
wiring and connections have a proportionately much greater effect on the
heat output of the 12v heater than on the 110v heater.  Theoretically the
heaters have exactly the same output, but in practice the 12v tends to be
less.  I haven't got numbers b/c I'm too lazy to pull the thing out and
measure voltage at the heater terminals, but that's how it works.  Each
half-volt drop at the heater will reduce the heat output by about 4 per
cent.  The same half-volt drop at the 110v heater comes to about 0.4 per cent.

In addition to that, I believe that the actual refrigeration cycle does not
work as well when the box is being driven around.  The whole cycle is
gravity-based and depends on fairly gentle declivities to persuade the
gases to flow down from the top of the reefer -- this surely is disturbed
when the box is shaken and accelerated fore-and-aft.  I have noticed an
immediate drop in output whenever the vehicle starts moving, and I'm rather
sure this is the cause.  It is independent of the heat source -- gas, 110v,
12v all show the same effect.

david
David Beierl - Providence, RI
  http://pws.prserv.net/synergy/Vanagon/
'84 Westy "Dutiful Passage"
'85 GL "Poor Relation"