oops, I screwed up with the subject line.  This one is better....

> One thing I worry about with > propane heater tapped to westy tank, is
freezing of external gas > lines, just downstream of reg.

Two things:

European gas specs always talk about butane/propane and have some
temperature cutoff to deal with this. We just have propane here.

We have two stage regulators to deal with cold temps. That's what the
2nd stage is for--to prevent freezing, or regulate in freezing temps.

The propane we have is fine to way too cold to camp.

I've camped in temps down to the low 20s and used my heater--a Carver
P4, now replaced with a Propex.

Disclaimer: here, we, etc, refer to the US of A. I can't speak of
primitive northern areas....

Richard