[VAC] Re: Balsa core flooring

[rlb <blammo@xxxxxxxxxxxxxx>]

"Dr. Gerald N. Johnson, electrical engineer" wrote:

> I think that product would be handy but its not structural, it depends
> on there being floor under or wall behind it. E.g. it won't span joists.
> The floor we've been talking about would span the joists with no other
> support.

I mentioned it for those thinking about retro-fitting (adding) to their trailer, over
the existing floor.

> 5/16" tube raises an interesting possibility useful in the RV. The large
> tubing is run all in series or sequence so the tubing diameter needs to
> be relatively large to control the pressure drop. But it means that the
> tubing closest to the heat source will always be warmer than the tubing
> near the other end of the run. In houses, the tubing run is arranged so
> that the beginning and end are next to each other and most of the run
> is  arranged with hot and cool parallel and adjacent so the average
> between them is always the same throughout the run. Going to a much
> smaller tubing can let on run a parallel phalanx of tubes from a common
> manifold at each end of the space to be heated. With out the meandering
> of the single tube system (but with more connections) draining should be
> a lot easier. I built an auxiliary radiator for a water cooled boat
> engine that once, used 3/4 copper pipe for the manifolds and 1/4" tubing
> for the parallel runs (swaged the ends down to make shoulder for support
> while soldering).

I was thinking along the same lines, just open the manifold at each end of the
trailer. and rock the trailer back and forth over the axles to drain it. I also
thought about another idea related to a radiator, as it were, these panels could also
be used to fabricate wall panels or even portable panels, ala your radiator idea, for
heating. The panels could even be installed high up on the wall, as long as the
convection action can get started, no fooling around with the structural floor, in
other word much lighter for retro-fitting.

Another idea just pop into my head, since there is generally little wall space near
the floor of an airstream, what about a wide baseboard setup, only nearer to waist
level. I wonder how hard it would be to build such a thing into or just beneath the
interior aluminum skin, 3 or 4 runs of the 5/16 tubing should do it, and the aluminum
skin on the inside could be the radiator. If four runs of tubing were used. and the
heat source were in the middle of the trailer somewhere, two runs could go out in each
direction and return in the other two runs of tubing. This has got some promise
somewhere in here, anyone want to go into business  :-)

Overall dimensions of such a system could be as low as 1/2" as long as the air can get
by the tubing, I would think that the water could be run at a higher temp also without
any discomfort problems, it also lends itself to being very customizable, in that the
"waistboard" (hey let's see if that word catches on) could be placed just about
anywhere on a wall. We could use an aluminum sheet for the radiator, might need some
corrugation to get the temp down where it could be brush up against.

The more I think about, the more uses I can think for it.

Sometimes I amaze myself.

Ok, now shoot that last one down. It sounds like too good an idea.

> > > Radiant heating is most effective when it can radiate to the occupants.
> > > That's how its efficient. It can't radiate from under the cabinets, and
> > > you sure don't need to be adding heat under the refrigerator...
> >
> > In a retro-fit (applying radiant floor over existing) I agree with you. I still
> > like the idea of some heat going into the cabinets, may be wasteful, but so be
> > it. If it make you any happier, you have convinced me not to put as much under
> > the cabinets as I would have before we traded posts   :-)
> >
> > > I don't know about a heat source. Needs a pump too. I suppose a surflo
> > > water pump will handle the temperature. There are versions that handle
> > > farm chemicals decently. Looking at the prices for electric tankless
> > > water heaters, I'm inclined to use a 2 or 6 gallon water heater tank for
> > > that application.
>
> Overnight I looked in the Shoup catalog and see that their surflo
> chemical demand pump is rated to operate to 170°F. 1.5 gpm for about
> $105. There probably would need to be some revision to disable the
> pressure demand switch or to make sure the pressure in the loop didn't
> rise enough to shut it off.

The pumps I just bought for the house loops (110v) were $70. They are a bit heavy, but
they are made for this type of application.

> > I think that with the small amount of water I would try out the smaller version,
> > 2 gal., especially with the 5/16" tubing.
>
> Then one might use an Atwood LP/electric RV heater to allow either fuel
> source.

To tell you the truth, I'm not a big fan of Gas, any kind of gas. But i understand
that there are others that would want it. Do you have and spec's on the heater,
dimensions, weight(s)?

> > > 5100 btu (1500 watts) is nearly enough for my Caravel, but something
> > > larger would need more to be comfortable.
> >
> > I may be able to get away with less BTU's than other with my Excella, I have the
> > double insulated glass versions of the windows. I wouldn't think I would need
> > more than 10,000 BTU's for the 30' trailer.
>
> Yes, my Caravel windows are single pane. But every Airstream has
> aluminum structure between the outside and inside wall. Just seeing a
> spray in place foam applied on the tube. I presume a variation on
> Icynene. Might be something beneficial to the major Airstream retrofit.
> R 6.5 per inch. 40 cents per board foot installed for open foam, 80
> cents per board foot installed for closed cell foam. Versus 20 cents a
> board foot for fiberglass. They say. Last I checked in Iowa the
> difference between the open cell foam and fiberglass was more like 3:1.
> The foam can't be installed except by a qualified contractor.

I already have one located for my addition and even have a bid for the whole job
including the basement ceilings. This stuff would be great for the walls of an A/S. I
was even thinking about while writing the waistboard stuff above.

You're starting to scare me Gerald, you think too much like me.  :-)

> > > The 1500 watt element standard
> > > in a 2 or 6 gallon electric water heater could be replaced by something
> > > larger. There needs to be an expansion chamber on the heating loop to
> > > allow for the changes of water volume when hot.
> >
> > I found what looked like about a 1 quart version in a catalog at the
> > contractor's today
>
> Should be a standard part of a closed loop water heat system.
>
> > <snip>
> > I wonder if two or three air chambers might not work for the expansion just
> > throw a pressure pop off in line, and everything would be good to go. The whole
> > thing including the electric heating would only take up the space of a small
> > suitcase.
>
> You can predict the expansion volume required from the volume of the
> system and the air space available in the expansion chamber and the
> expansion of water from 33° F (maximum density) up to say 140°F (to
> allow for a bit of over heat).

I'm not up on the mathematics of this, but I would imagine that there is a formula to
plug into somewhere.

bobb