Date: Mon, 06 Nov 95 11:16:59 mdt
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: jonesl@tcplink.nrel.gov
Subject: Re[2]: Tundra Toaster Heater and Propane Safety II
Scott - - -
Glad to hear from you in Atlanta. My mom is down there right now - when
she called last night, she said that she would have been better off
staying in Cheyenne, WY as far at the weather is concerned. Hopefully,
it won't stay that cold for long.
I understand your frustration with the heat in your bus. I have a daily
driver bug - the other day we had freezing rain here and I had to pull
over about once per mile to scrape the windshield - the "heater" just
wouldn't get enough warm air up to the defroster to get the job done.
And on really cold days I darn near freeze to death getting back and
forth to work.
Nevertheless, I would not put a propane catalytic heater in a vehicle.
First, some fundamentals - -
Omnes Gallia in tres partes divisa. (J. Caesar, Commentaries on the the
Gallic Wars). And the heat loss from your bus also comes in three
parts: (simplified non-technical version)
1) Infiltration - This comes from cold air entering and warm air leaving
the bus via bad door and window seals, rust holes (God Forbid!!), and
other unsealed openings. Infiltration, obviously, increases
proportionately (more or less) as the speed of the vehicle (or the wind
speed) increases.
2) Convection - This comes from air moving along the surfaces of your
bus, breaking up the "surface effect" and constantly exposing the
surface to fresh cold air. Like infiltration, convection increases as
the speed of the vehicle (or the wind speed) increases. Convection is
also directly proportional to surface area and temperature differential
as well as inversely proportional to the insulation value of the
material the heat is flowing thru. (In case you didn't already know,
sheet metal and glass have very little insulation value.)
3) Conduction - This is heat loss that occurs due to the temperature
differential between the inside and the outside of your bus. This is
directly proportional to the difference in temperature and to the area
of surface exposed and inversely proportional to the insulation value of
the material the heat is flowing thru. If you parked a heated bus
outside on a cold, still night - conduction is the only heat loss you
would have.
The key to effectively heating a vehicle (or your house or darn near
anything else) is to first reduce the heat requirement to a minimum.
Some suggestions:
1) Go over your bus with a fine toothed comb looking for air leaks.
Take it out on a cold night with a friend, drive around at freeway speed
and identify as many air leaks as possible.
Then fix 'em. Replace any bad door and window seals; adjust doors and
windows if necessary to seal properly. Look around the front, sides,
and rear of the van for any places that are leaking air - Fixtures like
headlights, turn signals, mounting brackets, holes for brake pedal,
clutch, etc. are all likely to leak air. Use foam sealant, caulking, or
other appropriate materials to seal 'em up. See your friendly local
builder's supply store.
Also look underneath the bus for air leaks. Best way to do this is to
wash the van underneath, let it dry - then crawl under it at night with
a marker or can of spray paint. Have a friend slowly and deliberately
illuminate every square inch of the floor of the bus. You will be able
to easily identify the air leaks by finding the sources of the light
leaking out. When you find 'em, mark 'em. Come back in daylight to fix
'em. A wide variety of materials from weatherstripping to welding rod
are available for appropriate use. Don't forget duct tape for a good,
if temporary fix.
2) Insulate your bus. Pull the interior upholstery panels, check behind
them. If there is insulation, make sure it covers the area as much as
possible and that it is properly installed. Fix any problems (you can
repair small areas with spray can foam). If there isn't any insulation,
get some and install it. Also check floor, headliner , and engine
comparment. There are a variety of self-adhesive foam automotive
insulation materials available that are not too difficult to install.
There was an article a few months ago in either VWT&A or Dune Buggies &
Hot Bimbos that outlined the use of one brand of material (Roadkill).
BONUS EFFECTS! - When you pull your panels, you can check and lubricate
window mechanisms, check wiring, check for rust, etc. Also, when you
install insulation you reduce road and engine noise as well as heat
loss. You may also wish to consider installing curtains on some of your
windows.
While you are working on reducing heat losses from your bus - also check
out the existing heating system. There's a pretty good section in
Muir's Idiot Book on how to do this. Basically, make sure that the
controls are working properly, that all dampers operate correctly, and
that the components, from the heater boxes forward are in good condition
(no holes, etc. in ducting, heater channels, etc.). Replace/repair as
required.
Once you have reduced the air leaks and other heat losses and have
corrected any problems with the heating system components, you will
probably find, as I did, that the heating system is much less
inadequate. Instead of arriving at work totally frozen, you'll just be
moderately frost-bit. In Atlanta, this may be good enough. In Colorado
- it really isn't. I always carry an old coat and some gloves in my
daily driver so I won't get caught by a cold snap by surprise.
If you want to go further with improving your heating system, let me
throw in a couple of ideas:
1) Get one or more 12v in-line "turbo" bilge blowers - find an
appropriate place(s) in your heating system and install it(them) to
boost the flow thru your heating system. Might wanna think about how
you do it to make sure that you don't accidentally short-ciruit cooling
air flow thru your oil cooler and cooling fins on cylinders/heads. You
can get kits to do this from a place called Barney's Import Parts in
Tucson, AZ ('94 price ~$70 - probably more now - see ads in VW mags) or
you could get the blower from your friendly local boat/marine dealer and
the other parts from a builder's supply house. I am in the process of
doing this now to on the driver's side of my daily driver bug. Costs:
Bilge Blower, 3" 140cfm $18
Flexible metal ducting, 3" 4
Duct Tape, 1 roll (only used ~4') 2
Clamps 2
Wire, Switch, spade connectors,etc. 6
-----
Total $32
This is essentially the same as the kit from Barney's. If I decide to
do the passenger's side, I'll have enough stuff left over to do it
except for the blower. As of last night, I have the fan installed (just
took out the section of ducting under the rear seat and put the fan in
its place). I hooked it up to my 12v battery charger for a test, and
boy can you feel the air coming out of the defroster outlet. I should
have the electrics hooked up in another day or so. I'll let you know
how it works on the road. If one is good, I'll figure that two should
be better - I'll buy the 2nd blower and install the passenger side as
well. BTW, the marine store I went to also had a 4" blower with higher
capacity (~200cfm) available for about $21-22. Considering the greater
volume and heat needs of a bus, a larger fan might be appropriate.
2) My other idea is to get and install a propane-fired vented RV type
heater in your bus. A variety of styles and capacities are available.
This would provide heat in the bus without the combustion products.
Again, I wouldn't do it, but if you do decide to use an infra-red type
heater in your bus - don't depend on air leakage - open a window. You
might consider using the heater just to warm up the bus interior before
you travel - then shutting it off. You should also be absolutely sure
that the heater/gas bottle can't tip over. Propane is a liquid - and if
the bottle tips over, you could have one helluva fire on your hands. (A
high school friend of mine was killed several year ago in an incident
where a propane heater tipped over in a duck blind!)
Whatever you decide - be as safe as you can be - and good luck!
______________________________ Reply Separator _________________________________
Subject: Re: Tundra Toaster Heater and Propane Safety II
Author: Scott Bogen <runwesty@onramp.net> at SMTP
Date: 11/5/95 3:10 PM
> I would be glad to respond to any questions or comments from anyone.
Hey Now,
I have a '77 westy and live in Atlanta GA, just moved here this past spring.
I have basicaly been deleting unread all the postings on heating the bus, I
was under the illusion (I lived my entire 33 years of life in Minneapolis)
that it did not get cold down here in Atlanta. Well that illusion crashed
last night as the temp dropped down below freezing and into the uppper 20s.
Not cold by Minnesota standards, but none the less cold. I froze my butt off
driving last night, and found the "heater" in the bus is less efficent than
having my dog just sit and pant on me. So today I headed off to REI to find
a little coleman propane heater, thinking well I can put it between the
front seats pointing toward the front and create a nice little warm zone.
REI had none, so I bought a bunch of Patagonia socks et al. So being that
this is my daily driver and love to driving it, yet also I do like being
warm, what suggestions-advise would you have for finding a way to heat the
bus while moving (the only camping planned at this point are excursions to
Florida). Is a small propane heater dangerous ie CO2 output if the bus is
moving? I found out last night that it is not the tight little boc that I
thought, rather has a number of drafts. Can a propane heater be used
intermittenly to warm the space and the shut off without danger of CO2
death. I understand the danger as far as having something that hot and with
a live fire in a moving vehicle. Any thoughts suggestions will be most
appreaciated.
Peace, "Now shake it, shake it Sugaree, I'll meet you at the jubilee,
Scoob and if that jubilee don't come, maybe I'll meet you on the run"
Jerry Garcia
