Externally-mounted element for boil kettle

Having just finished my first e-BIAB keggle, my mind has immediately started to wander: why couldn't the heating element be attached outside the kettle, on the bottom, like an electric skillet? I'm sure there are issues to be overcome (sourcing the right bendable element, figuring out how to attach it semi-permanently, maximizing heat transfer up into the kettle as opposed to down and away), but not having the element inside the kettle would certainly have some advantages. I'm imagining an element fixed to the outside bottom dome of a bottom-drain keggle.

I've done a bit of searching in the Electric Brewing and DIY forums and haven't found anything about this, so I thought I'd pose the question.

 

I've seen at least one kettle like this on here - I think it was near the start of the monster "Post your brew stand" thread in the DIY section.

You need the type of element used in electric ovens, and you'll lose a significant amount of heat relative to an immersed element (maybe 25%? at a guess), even with reflective metal below the element to redirect some of the heat up. You'll also have the potential for scorching on the bottom of the pot, the same as for propane burners.

 

Man, I looked quickly though the first 50-60 pages of that thread and nothing jumped out at me. Searching is kind of tough, too, with words like "element", "mount", "bottom", "keggle" and "kettle" being so common.

I assumed there would be some heat loss, but if the kettle was otherwise well insulated it might be okay. And maybe the scorching problem can be mitigated by spreading the heat evenly over the bottom of the kettle (i.e., using a longer element and lower heat).

Among the advantages that I can think of:

• No element to interfere with whirlpooling
• No element to clean (though this might be offset by increased effort required to clean the kettle itself)
• Less concern about scorching the bag while maintaining mash temperature (for BIAB brewers)
• No need to punch a hole in the side of the vessel for the element

Just pointless ramblings, I guess, but it would be very cool to come up with an easy way to "attach" heat to a keggle (or kettle).

 

Why not just use a heat stick? Of your benefits you listed above you could get most of those with a heat stick, you are not re-inventing the wheel, you don't have issues with heat loss as much. While it may be possible, I think it may be difficult. You are going to have issues with heat radiating down away from the kettle. This may also mess with the center drain that you mentioned. as the fittings and lines would be exposed to the heat. Probably can't use a wooden table but a metal one would work. Not sure what you will find for an adhesive that would be able to take the heat.

 

Good point about the heat stick addressing at least the first and last points. As a BIAB brewer I'd really like to get the element out of the kettle altogether to avoid any issues related to things (wort, bag, grains) coming in direct contact with it.

And besides, where's the fun in not reinventing the wheel?