7 Over:
I started with a home-built bbq drum roaster and avoided the weather problems by roasting in my shed. Propane has problems expanding properly at less than 20 degrees F so I did not roast when it was that cold but other than that, it worked just fine...
I brought this over from another thread. Talked with my brother this morning re: using my RK in these Lake Cheddar bitter winters. I was trying to learn, as he is a mechanical engineer and designed valves for years - propane and scuba tanks. He said that flow is impacted by BTUs, ambient temp, and internal vapor pressure. Internal vapor pressure decreases as ambient temp decreases and it slows the flow of the gas. As well, vapor pressure is impacted by the amount of propane that is in the tank; that's why you will see folks trying to top it off -- higher volume helps with prop up vapor pressure.
He said with my 46,000 BTU grill with a 20 lb tank, I will begin to experience some flow issues around 30 degrees and struggle around 20 degrees. I think he was saying that smaller units actually have an easier time than larger units. Beats the dickens out of me as he was rambling about thermal units and heat transfer or something.
He said I should grab a 40 lb tank. He did some mental math and said with that size tank and relatively full capacity, I should be able to roast down into single digits. If you go that route, he said make sure that the tank sits vertically. Don't tip a tank or have it on its side.
I think I will have Peter over for a discussion and then, in front of him, I will suggest to the Czarina that I really need a 40 lb tank for the grill for better efficiency. That will cushion the scream.
For what it is worth; your mileage may vary. I am going to find out this winter if mine does.
B|Java