Date: Sun, 26 Nov 2006 12:06:36 -0500
Reply-To: Edward Maglott <emaglott@BUNCOMBE.MAIN.NC.US>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Edward Maglott <emaglott@BUNCOMBE.MAIN.NC.US>
Subject: Re: Aircooled? - building my own interior heating system!
In-Reply-To: <F35A231E-FD9A-45FF-9A6A-1F2D009993C0@pottsfamily.ca>
Content-Type: text/plain; charset="us-ascii"; format=flowed
Greg pretty much sums up the wattage issues here. Think about how much
heat your little ceramic heater puts out. That's probably 1500w. That
gives you some idea of how much heat you are going to get from that
100-120w heater. FWIW, a 1500w heater is about 5200btu. So you can also
compare that to the heat output of your catalytic heater. The other
question that comes to mind is why add the complexity of heating the fluid
to heat the air? In your MB veggie oil heater set up, you are only heating
a small amount of oil at a time. That's the big difference as to why this
wont' work to heat the interior of the van.
I had a '69 Westy with a 12,000 BTU propane furnace in it. It was plenty
when the van was parked, but couldn't really keep it warn when moving. It
was rusty with lots of air leaks.
I'm pretty sure the EV1 (aka "Impact") used a heat pump to heat and cool
the interior.
Edward
At 05:20 PM 11/25/2006, Greg Potts wrote:
>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.
>>
>>---
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