From: John De Armond
Subject: Re: RV Hot Water Systems (was CG Showers)
Message-ID: <39358A04.2252A436@bellsouth.net>
Date: Wed, 31 May 2000 17:54:13 EDT
Newsgroups: alt.rv,rec.outdoors.rv-travel

"D. Reaves" wrote:

> This was ONE water heater, not two heaters/systems on the '83 Airstream
> (A/S) Class A, 30' motorhome. Upon arrival at our destination, we had
> instant *very* hot water -- hotter than what the propane provided -- so
> that more cold water was used (despite the small six gallon tank) to
> allow the temp to be comfortable and not conducive to burns.
> 
> As you've figured out by now, the water was being heated continuously by
> the hot water in the engine's radiator. The hose from the radiator to
> the "car" heater had a T that gave access to another hose that ran to
> the water heater tank. That hose was connected to a copper coil inside
> the tank that circulated the hot radiator water, thereby heating the
> water in the tank. Another similar hose and T setup hose returned the
> cold water to the radiator.

That kind of heater is still available.  I saw one for sale at our
local RV store (Shipp's RV service, Chattanooga, TN) awhile back. 
No idea what brand.  Logical for a motorhome, a bit more complicated
for a trailer as you note.

> Although we did not have any problems, potential disaster could take
> place. DH (Dear Husband) suggests cut offs at all T's, not just at
> water heater/tank. The hoses to and from "car" heater was long and
> hidden in wall. If it broke or leaked... !!!! Damage to RV coach
> interior and ruined engine if no water in radiator!

If I was setting such a system up for a trailer, I'd do things a bit
backwards.  I'd put the heat exchanger in the vehicle and then have
a small pump circulate water heater water to and from the
exchanger.  That way, all a leak does is leak out the fresh water. 
If the tubing is run under the trailer, then there's little risk of
water damage.  

I'm very interested in how the liquid lines connected between the
trailer and the tow vehicle in your old Air Stream.

> Probably impractical or too expensive to "make your own," but it's
> something to think about since one can't find such a set in, for
> example, Camping World. Another idea inspired by picturing the anode rod
> in older water heaters: add AC power to heat water and save propane. See
> the under $100 "Hott Rod" in Camping World catalog. Make your own?

These can be made very cheaply, for less than $10.  I've made a
bunch of these for use on refrigeration system in my restaurant as
de-superheaters. Improves both the efficiency and the cooling
capacity. All that is involved is a couple of lengths of rigid
copper tubing and two reducing tees.

Let's say that we're using 1/2" tubing for the core and 3/4" tubing
for the jacket.  For a one foot (nominal) long exchanger, you'd need
a foot of 3/4" tubing, about 15 inches of 1/2" tubing and a couple
of 1/2 X 1/2 X 3/4 reducing sweat (solder) tees.  Everything is
available at Ace Hardware, Lowe's, Home Depot, etc.

This tee will have the side leg for 1/2" tubing, one straight leg
for 1/2" tubing and one straight leg for 3/4" tubing.  The 1/2"
straight leg has a little ridge in it to keep the tubing from
extending into the tee.  If this ridge is reamed out (with a pocket
knife or rat tailed file), then 1/2" tubing can be passed through
the tee to the 3/4" tubing.  this is the key.

After reaming the ridges, one simply pushes a tee onto each end of
the 3/4" tubing.  The 15 inch length of 1/2" tube is then pushed
from one tee through the 3/4" tubing and out the other tee. Center
this tubing so that an equal amount sticks out on each end.  Insert
short stubs of 1/2" tubing into the side legs. All joints are then
soldered (silver soldered if you really care :-)

Viola!!!  Instant heat exchanger.  Radiator hose can be simply
slipped over the copper tubing and secured with worm clamps or one
can solder on hose nipples.  

It literally takes longer to describe how to do it than to make the
thing.

> Not what I had in mind but great site for campers, John. Liked the
> $24.95 outside shower enclosure. Could be used for RVs for outside
> showers. Thanks for URL.

Yer welcome.  Here's another URL for outside showers
http://www.bivouacbuddy.com/index.html  I actually like the look of
this one better.  The one pictured on the home page has a built-in
reservoir but if you look on the order page, they offer it without
the reservoir.  This is on my to-buy list for extended dry camping.

John