I need some advice for a friend who has obtained a vented propane Southern Burner heater for his greenhouse. He needs advice in connecting it. I use Southern Burners, but mine are natural gas. Can anyone advise...is it OK to just use the flex tubing used to connect stoves? Can you hook two small tanks together and open the second when the first one is low, or will the pressure in the two just equalize? Do you put the tank outside the greenhouse, or is it OK to be inside? Does anyone have any tips or a resource he could go to? He wants to be sure he does it right....thanks!