On Fri, 17 Oct 2014 18:44:12 GMT, (Scott Lurndal)
wrote:

Jeff Liebermann writes:
On Fri, 17 Oct 2014 11:45:50 -0400, micky
wrote:
Also, if there were a soft plastic inside liner, I
would expect it to melt from the heat of gas flame at the bottom.

Have you never boiled water in a styrofoam cup over an open flame?

Yes. It requires a heat spreader between the cup and the flame. Apply
the flame directly and the hot spot will burn a hole in the styrofoam.

One can. The water keeps the temperature of the foam below its
melting point.

True. However, a gas water heater has to deal with stratification,
where the water is much hotter near the flame than near the tank
outlet. I couldn't determine how much of a temperature difference by
Googling. You're probably correct that it won't melt if it's decent
plastic, but I'm still suspicious. Unless secured to the steel tank,
it might soften, warp, bend, buckle, or otherwise provide an excuse
for water to get to the steel. From there, it's only the anode rod
that protects the steel tank from corrosion.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558