I put that hose insulation along the source hose of my heater, except for a
short section above the tank. Results are significant! Heater is finally
working like it should. Seems the long travel to the front was sapping its'
heat. 'Specially in very cold weather.
There are two kinds of tube insulation, which I got at Home Depot. This is
the cheapest so it doesn't have a self adhesive seam. After tying it with
temporary wires I injected it with Polyurethane foam which you can even see
in the rear of this picture:
http://www.Gnarlodious.com/Vanagon/Vanagon_Notes.html#heater
I didn't do the return hose, it seemed a little superfluous

Note to the adventurous: this is a dirty job! Wear goggles. After applying
foam wait until it is completely hard before driving or running hot water in
the hose. Vibration causes it to collapse and heat causes it to expand
beyond usefulness.

Hope that makes sense . . .

-- Rachel
http://www.Spectrumology.com
AIM Gnarlodious