This is not a BBQ question, but I couldn't think of a better place to
post. I have two recently-filled 20lbs LP tanks. I hooked one up to an
outdoor patio heater (new from Costco) and the regulator iced up and
after about 5 minuted the gas cut off. When I hooked up the 2nd tank,
everything worked fine. This is in northern CA and the temperature was
probably 60F and not humid.

Why would one tank make the regulator freeze ? There was frost on the
regular surface. Is there water in the tank or something? When I use
the "good" tank, the regulator is slightly cool but that's all. Both
tanks were filled by the same LP dealer at the same time.

Any ideas?