I don't think you are getting any responses because (at least to me) your question doesn't make sense. A fire pit is for fun, not to warm a perimeter. The hotter you make the fire, the warmer it will be. They are not however designed to "heat" a whole patio area. The air that gets heated quickly gets mixed with cooler air. Only when you are real close to a fire do you find yourself backing up because it is too cool.
Again, they are more for ambiance than to heat a large area when it is 20ð

Outdoor heaters like you see at restaurants with outdoor patios.

I know they don't heat a patio area, but a fire pit/table is meant to sit around. If you have only 30k-40k btu, they are more or less for ambience. If you have a real wood fire pit, if your close you easily could go at 20 degrees considered your dressed appropriately. I guess I was hoping some people have natural gas fire pits of say 150k btu and they say they are pretty comfortable within 5 ft or soo.