Heating Time in Electric vs Gas-Fired Kettles

[DrPaulsen]

While getting ready to brew a 10 gallon batch of Helles yesterday morning, I decided to heat my MLT strike water in the BK, while my HLT was heating up separately. I couldn't fit both the 9 gallons of strike water and the 11 gallons of sparge water in my HLT, so this gave me an opportunity to do a side-by-side comparison of an electric kettle and a gas-fired kettle.

I recorded the temperature of each kettle every 5 minutes from their starting temp of 60F until it was time to stop heating (around 140F). Since the gas burner was heating 9 gallons of water and the electric element was heating 11 gallons, I scaled both sets of results to 10 gallons and plotted both sets of data in the attached file.

I know the heating element was running wide open at 4500 W (around 15k BTU/hr), but I'm not sure at what output the propane burner was running. If I had to guess, I'd say it was about 50%, which would be around 36k BTU/hr. Interestingly, both of these two kettles heated at almost the exact same rate. Aside from the fact that this means 50% of the energy from the gas burner is being wasted, it also points to a much more pragmatic conclusion -- heating electric kettles really doesn't take any extra time than with gas. This is something I'd always suspected, but never had an opportunity to directly measure.

Blichmann's website claims that if the burner is run wide-open, it should be able to heat 10 gallons of water from 60F to 160F in about 15 mins. (The link is below, but you'll need to click on the "burner data" tab to see the plot to which I'm referring.) I'll have to try this again sometime with the burner running wide open, but 50% did seem a comfortable level, relative to the temperature of the fittings hanging off the kettle (ball valves, thermometer, etc.).

http://www.blichmannengineering.com/bre ... dular.html