Setting up an electric brewery in the basement and just thought about how I’m going to do decoctions when desired. I brew 5-gallon batches and so I thought maybe a portable induction cooktop would fit the bill.
I’m looking at an 1800 W induction cooktop and a 12 Qt. stainless pot with a 6010-clad bottom suitable for induction cooking. I figure the 3-gallon pot not only would fit the cooktop real well, but also would hold enough to do a decoction for a 5-gallon batch assuming I’d never pull more than, say, 2.5 gallons of thick mash. And 1800 W should be sufficient to raise the temperature of the decoction to its rest temperature, then bring it up to a boil pretty quickly.
I’ve not done a decoction on my induction cooktop, but I can say that I boil ~7 - 7.5 gal collected sweet wort with 2 - 2.4kw. Based on this I believe your 1.8kw unit should handle 2.5 gal easily.
I can vouch for an induction cooktop working for decoction. I brewed on an 1800w cooktop for yrs & it can bring 3.5gal of wort to a rolling boil no problem. I only did one decoction mash to try it. Induction provided great control & brought it to boil fast w/o burning.
The only tip I have is if you are taking any temp readings w/ a metal thermometer in the decoction while the cooktop is on, it throws the temp reading (digital & analog thermometers, I tested both). 3 batches in a row when down the drain because I was multi-step BIAB mashing & taking temp readings that I discovered later were upwards of 10 degrees off because of the cooktop.