some questions after changing to propane

I finally got fed up with ethanol gasoline messing up my carb on a self propelled mower, so decided to try propane. I just removed the fuel tank and plugged the carb fuel line. Then added a small propane torch size bottle, drilled a hole in the air filter, and added a regulator and hose from a grill, using the brass part with the small hole poking toward the intake of the engine. It works good, but has to be started with starting fluid. I use the knob on the regulator to control the speed.



At first I lay the bottle down, but the regulator froze so had to mount it upright. Now after 20 minutes or so, the bottom half of the tank is frosted over.



So my questions are, why won't it start off the propane even with the engine hot and why does the propane tank freeze like this? Do I need to change the plug to a different heat or does that matter?



Thanks,

Alan