Just tested my single tier setup last night. Was extremely surprised how long it too me to heat water. It took close to 2 hours to heat 10 gallons from 60 degrees.
I am using 10" banjo burners with low pressure propane and low pressure orifices and 20 gal blichmann boilermakers. To be honest, the flames look strong and powerful- mainly blue with a little yellow on the tips. I have the kettles 3" above the flame and have to dial the flame down to keep flames from going up the sides of the kettle.
Any ideas or advice would be extremely helpful. Seriously did not expect 2 hours to heat water!