Hi there - I am looking to move to induction brewing as I am moving to an apartment. I technically have 240v but would rather not deal with an adapter. I like to brew 10 gallon batches. Would there be any way to do this with an 1800w (120v) burner, with lots of insulation? If not would a 3500W (240v) work? Worst case scenario would be spending 2x the money on a bigger burner and another $100 on an adapter and 240v extension chord. Perhaps there is a meet in the middle and I could somehow do a 7-8 gallon brew on an 1800W and get a gallon or two on the stove top???
From research I did a while back, you'd be hard pressed to do 5 gallon batches with 120V, let alone 10 gallon batches. Though of course I defer to anyone here who has actually tried it.
Cool thing about electric stoves, or anything electric, is they all produce pretty much identical heat from the current. So 1500 watts is 1500 watts is 1500 watts. That equals 5,100 BTUs. There is no magic efficiency or technology. 1800 watts is 6,140 BTUs. But you will be hard pressed to get 1800 watts on a typical 120 volt household circuit. The line is rated for 80% power delivery and even then it is difficult to maintain. 14 gauge wire (again, typical) can not safely deliver 1600 watts. Nor will it have a 20 amp breaker on the other end. For reference, the largest burner on a typical LP or NG domestic stove is about 12,000 BTUs. That is just enough to get 5 gallons boiling. Less than half of that is not going to do much. With 10 gallons to boil, forget it. Insulation is not the answer I'm afraid. I sometimes pre-boil my sparge water on the stove to remove temporary hardness. 4 or 5 gallons on a 12,000 BTU burner will boil, but barely. Go to 240 if you can. Cheers.
There was a recent article in BYO on this topic that you might find helpful, although I'm not sure it addresses your particular situation. One thing I've started doing is splitting my boil across two burners on my stove (two separate kettles). I can actually get a decent boil in 5 gallons on one burner, but it's faster and easier using two burners. Anyway just something to think about.
Not to go off on a tangent (though that's what the internet is for), but you're correct that electric resistance heat is, indeed, 100% efficient. Curiously, an electric heat pump can achieve an apparent efficiency of 300% or more - for every 1500 watts registered on your meter, you're pumping 4500 watts worth of BTUs into your home. Back on topic, yes, 120VAC will be a problem for anything over a couple of gallons. It's doable, but the result is unlikely to be optimal. I once did a 5 gallon batch using two electric burners - 3,000 watts @240VAC each. Even that makes for a long brew day. My 15K BTU gas stove-top burner is just barely up to the task of 5 gallons. I'll occasionally use that for extract brews during the long winter months when the outdoor brewery is not practical.
I have two 2100 Watt induction burners and two 5.5 Gal kettles. With a bit of fermcap I can fill them to the brim and get a good enough boil. I think that pic it is just coming upto boil, doesn’t look impressive like the rolling boil you get with propane but it’s good enough for ~3 litres/ hour evaporation without the need for insulation. I’d bet an insulated 3500W burner could boil 10g+ but that much weight would be over the safe limit of the glass top.
