Thanks Jim. Any further testing is going to have to wait as a urgent family matter has come about overnight and we are getting ready to leave in about 2 hours. By time we get back, probably sometime next week, our cold spell here will be over...

I have a stove that use those slim butane canisters, and even in ambient temperature in the high 20's, after some use the canister would get cool enough to unable to supply a strong flame,

HJ--no joke--

a comment if you are dealing with kids and gas cylinders...we used to use the GAZ cylinders for our "Bunsen burners" in chem lab, with the type shown in CANOEDOGS's photo, once punctured, no way to shut off the gas except with the burner valve... a fellow teacher walked into my class one day with a punctured cylinder spewing gas (one of his angels had popped the top off)... I grabbed it and headed for the window, but a PE class was passing underneath, threw it in the vent hood, had the students look away, and hoped the vent switch and motor were explosion proof as noted and flipped the switch... we affectionately referred to them thereafter as hand grenades...switched to a source (Lentz?) with a self contained Schrader valve (tire type valve) to shut off fuel if the burner is removed...