Propane Burner Efficiency

A comment in a recent post in another thread
http://forum.northernbrewer.com/viewtopic.php?f=1&t=114359&start=15#p1001353
has inspired me to inquire from the community: how many brew sessions do you normally get from a tank of propane, what burner do you use, what size batches do you brew and how long do you typically boil for?

I use a Bayou Classic and normally get 3-4 five gallon batches and average ~75 minute boils. After reading some comments in the linked thread above, I’m considering upgrading to the Blichmann burner. I’m no math geek, but if the Blichmann allows you to stretch a tank of propane that much, it would pay for itself over time.

I use the SQ14 and get 3 10 gallon batches to a tank, sometimes i feel like i could push it to 4 but running out of propane sucks a lot. This is also using a keggle which is known for inefficient heat transfer.

I bought this burner about 2 years ago and kinda wish i would have gone for the blichman, but at the same time i like leaving my burner outside and just wouldnt be able to do that to all that nice pretty stainless.

I will probably upgrade my kettle before i replace the burner, although I am mostly happy with my setup as is.

EDIT forgot to add that i use a bucket heater on a timer to heat my strike water so that it is good to go as soon as i wake up and doesnt use any propane.

I have the Blichmann Floor Burner. I usually get 5-6 full boil 5 gallon extract batches to a 20lb Tank.
Often when you exchange a tank you only get 15-17lbs. I (almost) always have them filled to the full 20lb.
I also have 2 extra tanks and brew where I’m protected from the wind.

Now that I’ve started all grain, I’m certain I’ll be going through more heating strike and sparge water.

I will say, the Blichmann is faster than the Bayou getting things up to heat.

A friend has the Bayou and on a windy night, we couldn’t even get a boil. The Blichmann didn’t have a problem. (We’ve since manufactured a wind screen for the Bayou)

I can stretch it out to 8-10 6 gallon batches per 20 lbs tank (only if I heat my sparge water inside on our gas range). Once I get to a boil on the Blichmann, I can turn it down really low and still maintain a good boil.