I like the science...but not enough to go find and study all the
permutations of whether catalytic propane heaters produce less water vapor
than a pure and simple propane flame, in verified laboratory experiments....
 In my van that is the case by my own observation, and since my Vanagon is
no different than most, I figure others, who may be seeing only the science
that says (sic) " ...Cups of water per lb. ...." might be all worried about
having a wet van when using one of these heaters.... It works well for me,
and in our camp trailer, it works well too.  😁   Maybe the water is
produced, but it's not showing up as anything I can see or feel.  The heat
is good.

On Dec 22, 2016 9:19 AM, "David McNeely" <davmcneely40@gmail.com> wrote:

> Alistair, how dare you to bring scientific facts to a modern discussion ;-}
> !
>
> Of course, the important fact for Don is whether or not he perceives the
> interior of his van as wet.  I too have experienced steaming up with the
> cooktop.  It may be that when Don is running the heater, the interior
> surfaces are warm, and the moisture does not condense, but that when we run
> the stove without a heater, the interior surfaces are cool, and the
> moisture condenses.  Moisture does not condense on my drink glasses at home
> unless I put ice in them.
>
> mcneely
>
> On Thu, Dec 22, 2016 at 8:58 AM, Alistair Bell <albell@shaw.ca> wrote:
>
> > It's not that dons perceptions are invalid. It's rather that burning
> > propane does produce water ( in the environment we live in anyway) and
> the
> > amount of water produced is predictable. Predictable with some certainty
> > and is not fake news.
> >
> > If that water vapour is noticeable or not, is another issue. I worked it
> > out as almost 3 cups of water for every pound of propane burned.  If that
> > seems like a lot or not, is up to you :-)
> >
> > I think I balanced the equations and made reasonable assumptions in the
> > following.
> > For a one pounder, and lets make assumption that no CO is produced, ie
> the
> > heater is working perfectly, and that there are 16 oz to the lb, or 454
> g.
> >
> > combustion equation:
> >
> > C3H8 + 5O2 -----> 3 CO2 + 4H2O
> >
> > i.e. for every mole of propane burned, we get 4 moles of water.
> >
> > molecular weight of propane = 44 g/mol
> >
> > moles per 1 lb bottle = 454/44 = 10.3 moles
> >
> > therefore burning the entire bottle would produce 4(10.3) = 41.2 moles of
> > water
> >
> > molecular weight of water = 18 g/mole
> >
> > therefore 18(41.2) = 741.6 g of water produced.
> >
> > almost 3 cups of water into the van when one pound of propane burned.
> >
> >
> > alistair
> >
> >
> >
> > > On Dec 22, 2016, at 8:42 AM, Patrick Spragge <spraggepat@gmail.com>
> > wrote:
> > >
> > > Perhaps I'll comment on these 2 messages on Friday.
> > >
> > >
> > >
> > > Patrick Spragge
> > >
> > >> On Dec 22, 2016, at 8:27 AM, Alistair Bell <albell@SHAW.CA> wrote:
> > >>
> > >> If you look at the chemistry of propane combustion and you spend some
> > time to understand it, then you will see how much water vapour is
> produced
> > per unit of propane burned.
> > >>
> > >> It's is not fake news or exageraration. It's basic science. As
> > unpopular as science is these days, it still rules.
> > >>
> > >>
> > >> Alistair
> > >>
> > >>> On Dec 22, 2016, at 8:20 AM, Don Hanson <dhanson928@GMAIL.COM>
> wrote:
> > >>>
> > >>> The word was the Mr. Heater, and others, catalytic propane, create a
> > lot of
> > >>> water vapour in a Vanagon.  That seems to be fake news, or perhaps an
> > >>> exaggeration.
> > >>> I've been running two now, in the wet southwest desert, one in a camp
> > >>> trailer and one in the "annex" (my Vanagon)   Fairly humid here
> > now,and no
> > >>> interior moisture problem at all.  Perhaps the catalytic combustion
> is
> > >>> dryer than people have said..
> > >>>  Now when I ignite the Westie cook top, the Vanagon steams right up,
> > >>> immediately.
> > >>>   So there you go, a report of one family's (two humans and three
> large
> > >>> Chesepeake dogs, full timing with two Mr. Heaters as our comfort
> heat)
> >
>