I just got
http://www.amazon.com/Bayou-Classic-SP10-High-Pressure-Outdoor/dp/B000291GBQ/ref=sr_1_3?ie=UTF8&s=home-garden&qid=1217100692&sr=8-3 I figured it was good because 185,000 btu and the AHS high output one is 210,000 btu.
Anyone that ordered this can you post the btu output of the burner.
If the 185k BTU output is BTUs per hour, just as a heads up, the math works out to, with perfect heat conversion, about 8.6 pounds of propane an hour. With thermal dynamics and inefficiency, I'd up that to around 9.5 pounds an hour potentially (depending on wind, fuel mixture, and other things). This is a disgustingly high fuel consumption rate, and I'd probably look into some kind of insulation collar to improve my efficiency.
This explains why people are blowing entire 20 pound cylinders on one brewday.
BTW, the fuel consumption rate is pretty simple.
2500 BTUs per cubic foot of propane.
A cubic foot of propane weighs .1162 pounds.
Divide your BTU/hour output by 2500 to get cubic feet per hour.
Multiply by .1162 pounds and you get pounds of propane per hour under "perfect" conditions.
Natural gas, by comparison, has about 1000 BTUs per cubic foot, which is why propane is so much more efficient.
Oh, and as a further example, we'll do the 210k burner's fuel consumption.
210,000 BTUs/hour Divided by 2500 BTUs per cubic foot = 84 cubic feet per hour.
84 cubic feet/hour times .1162 pounds of propane/cubic foot = 9.76 pounds of propane/hour.
Let's give that a reasonable 90% efficiency (so you loose 10% extra fuel due to physical impossibility to get a "perfect, lab environment" of fuel mixture, frictionless surfaces, ect ect) and you get 10.74 pounds of propane per hour.
Finally, with that kind of massive pull off of a propane tank, we're seriously looking at maybe as much as the last half of the tank freezing up, due to liquid propane flashing into gas being endothermic. As the tank empties, the temperature drops, your pressure drops, and you become more inefficient.
My solution would be to either step up to a large 60 pound propane cylinder (I use two on a manifold for my blacksmith forge, which uses maybe 2 pounds of propane an hour by comparison, and I've never frozen up since then) so that you have a far longer time before freezing your propane. The second solution is to either build or buy (you can buy for about 15 bucks) a 2-tank manifold, and hook up two twenty pound cylinders. This way, each tank is contributing half the fuel rate needed, and hopefully the tanks will stay warm far, far longer.
The more I look into this, the more I want to custom build brew burners and ceramic insulation collars. I could push this down to maybe 70,000 BTUs, and with some insulation, get you boiling, in all probability, faster than you ever would with the 200k burner.