Hi Mike,

A gas heater or propane/gasoline/diesel furnace emits thousands of
watts from combustion. In order to get that much energy out of a
liquid you  have to be able put it in to the liquid first. How the
energy is distributed is irrelevant: if you are transferring the heat
from liquid to the cab of the van you have top be able to put it back
into the liquid or the rad soon goes cold and the van goes cold.

So lets look at the wattage and voltage requirements.  Veggie oil
heaters like this one:
http://www.kenneke.com/veggie.html are rated at 10 amps of 12V. Watts
= Volts X Amps. That electrical draw translates to provide 120 watts
of heat.  Less if there are thermal inefficiencies in the heater
design.  Are you going to heat the entire van with the equivalent of
two 60W light bulbs? I don't think so. If you want to generate 1000W
of heat you are going to need to pull  about 80 Amps out of your
battery, and a Vanagon alternator isn't rated for that much extra
load. I suppose you could fit a spare alternator into an AC bracket
but that's getting complicated and your engine really doesn't need to
give up any additional HP.

Honestly (And since all the above was honest, so why am I singling
out this particular paragraph? I don't know, it's just a figure of
speech I guess.): You'd be warmer in the long run spending that $200
replacing your heater boxes or buying espar or southwind furnaces at
swap meets. or buy a black cat heater and keep a window cracked. Or
buy some heated clothing, or a nice warm hat and mitts.

Happy Trails,

Greg Potts
1973/74/75/77/79 Westfakia "Bob the Tomato"
www.pottsfamily.ca/westfakia
www.busesofthecorn.com

On 25-Nov-06, at 3:33 PM, Mike Rouby wrote:

> Actually, electric vehicles heat the interior using 'waste' heat
> transfer usually.  The heat off the electric process/motors is
> recycled to heat the interior.
>
> However, I am quite convinced that this may work - enough to dump
> $200 (total cost) into the project.  If successful, I will fit it
> into the Vanagon as a permanent device.  Initially, I will bench
> test the entire assembly on a table.
>
> Thinking out loud, I may use vegetable oil instead of water/
> antifreeze (similar concept to an oil-filled radiator) as a
> conductor.  Only issue with that, is that it may take some time to
> warm up.
>
> Wil Haslup <whaslup@GMAIL.COM> wrote: Greg Potts wrote:
>> Hi Mike,
>
>> It's not going to work. You can't extract enough energy from a 12V
>> battery to heat 180 cubic feet of Vanagon interior. Your alternator
>> could not keep up with the draw, either. It's basic physics, and the
>> question has come up on the aircooled list every fall since the lists
>> started.  If it was practical, automotive engineers would have
>> adopted electrical heating a long time ago.
>
>> There are tiny little 12V hairdryers that are popular for defrosting
>> bus windshields, but they don't supply enough heat to warm the
>> interior of a bug.
>
>> The best approach for electric heat in a vehicle is to wear heated
>> clothing. That might not be as convenient, but it will work.
>> http://cozywinters.com/heated-clothing/?
>> source=go&gclid=CMSk6eXm4ogCFSLrPgodnGpapQ
>
> While my original post mentioned my questions of the amount of amps
> being drawn being too much, I'm not certain that would make this
> scheme
> unworkable.
>
> ---