Westy Hot Water Heat Exchange System

David Garth's Hot Water Invention
This is a picture of David Garth's heat transfer hot water invemtion.  I borrowed his design, and ran a copper coolant line from the rear heater into the water tank.  The set up heats the 13 gallons of hot water to 105 degrees in about 30 minutes of freeway driving.  I have insulated the tank and the water stays warm overnight and is pleasantly warm in the morning.  It is great for use while in transit, too.  Thanks for the great design idea, David!

Here is a description of the project and a parts list from an old e-mail to the Vanagon list:
I tapped into the heater hoses with tees under the rear
heater box.  I ran one line into a 24 volt ac selonoid valve, which fits
under the rear heater box.  from there, i ran 1/4" copper tubing into the
hidden utiltiy compartment and up into the water tank.  I heated a
1" piece of metal pipe to burn 1" holes in the top of the tank to run
the 1/4" line.  i used rubber gromets to seal the pipe and
holes....got larger ones to protect the palstic from heat.  i then coiled 15' of
1/4" copper tubing and inserted it into the tank.  it did not take up
much room at all.

i moved the water level gauge from the tank lid to the tank
where it is out of the way (it's  nicer there)  i used 90 degree flared
elbows at the top of the tank to connect the submeresed coil to the
feed and return lines running from the heater hoses.  i insulated the
lines where i thought appropriate to protect from burns and to protect

i hooked up a main power switch for the selonoid valve.
this, in turn, is hooked up to the water bed thermostat.  if the water temp
is below 100 degrees, the therrmostat allows power to flow to the
selonoid valve, which causes the valve to open, and the coolant to
flow.  when the temp reaches about 105 degrees, the thermostat cuts off
power to the valve, and the coolant flow stops so that it does not become
dangerously hot.

i ended up using compression fittings and flared fittings.   I used both because i could not find everything i needed in either type.  I also ended up making a reduction (or increase) in tubing size I did not need to but for the fact that i did not have enough of the right sized tubing.

A parts list follows:
~ two 1/2" brass tees with compression fittings to tap into
the heater hoses at rear heater;

~ two 1/2" to 3/8" reducers with compression fittings

~ one 3/8" flared to 1/2" pipe threaded fitting, which bolts
into the selonoid valve;

~ one 1/2" threaded pipe to 3/8" flared fitting, which bolts
on other side of selonoid;

~ one 3/8" flared to 1/4" flared reducer
~ one 3/8" to 1/4" flared reducer (for the return line)
~ 4 1/4" flare nuts
~ 2 3/8" fare nuts
~ 25' of 1/4" copper tubing
~ 18" of 3/8" copper tubing
~ 1' of 1/2" inch copper tubing

~ one  high temperature HOT WATER/STEAM selenoid
valve (1a582) and 24 volt AC selenoid from Grangier
(800-225-5994) for $98.

~ one waterbed thermostat (get a mechanical one...not
electronic like i did)
~ rubber gromets for sealing water tank where coolant lines
enter and exit
~ one lighted electrical switch
~ -in line fuse
~ sealed (not loose) pipe insulation
~ pipe joint goop

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