Strangely enough the little camping gaz torches don't flare, as long as let the nozzle heat up properly before turning them upside down, they also have a nice wide base so don't fall over easily. Ive also lost the small nozzle for the bottle torch, next size up is fine upto 28mm pipe but a bit ifffy underfloor. I was really just trying to say to the OP that you don't need that much heat to make a good solder join.