-> I haven't seen them, but there could be bimetal valves to do the
-> trick. But I would suspect the only economicly feasible way to go is
-> with electric switching.
Chris, I hate to remind you but guesses are sometimes misleading.  Gas
regulators have been handling this problem longer than you've been
ALIVE!
 ^..^
--- FidoPCB v1.5 beta-'j'
---------------