Date: Mon, 6 Nov 95 17:28:42 GMT-28871216:51
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: jag@cs.rochester.edu
Subject: Re: Keeping Warm
Bob, thanks for the detailed elaboration on heat conservation in the Bus.
I had originally planned on doing my bus with fiberglass and styrofoam,
however the spray-on uretane foam you talk about appeals to me.
A few questions?
Were do you get the chemicals needed in bus suitable quantities? I know
where to buy the 10 oz spray can size (Great Stuff), but at 4.99 a bottle
that would be prohibitive. I've also heard that there are contractors
who insulate houses this way, but again, I believe they use expensive
equipment to inject or spray on the foam. Are there any other sources
of this kind of foam?
How do you do the front doors? I see two problems in the vanagon:
The sheet metal on the inside obstructs access, so it might be tricky
to spray the foam on evenly. Another approach might be to fill the whole
cavity and try to cut out room for the locks and window mechanism.
The other problem i fear is water getting caught between the insulation
and the sheet metal, causing rust. This could happen if there were voids
or cracks in the insulation, or if the foam is not sufficiently impermeable
to water vapor.
Otherwise the urethane foam idea sounded great. Should be much better than
the fiberglass approach.
Another note. It would be great if we could collect some data
here on the list on the effectiveness of different insulation
methods. My suggestion to the listmembers who are insulating their
busses is: Measure the bus heat loss before and
after insulation has been put in by putting an electric heater in
the bus. Run the heater until thermal equilibrium is reached, and
measure the temperature difference inside and outside the bus.
The experiment would be most accurate in a garage, where the outside
temperature can be kept fixed.
Knowledge of the temperature difference and the wattage of the heater
allows one to calculate the heat loss.
/Martin
