Yes u are right on . My going crazy on flak-spammer said . But I can do that with 2 168w or 2 400w peltier @ 50% power on them . 3kw is about 1094c(2000F) on a 2 inch piece metal . But runnig 8 45.6w peltier will cool it down more evenly on the block .
You havent listened to what I said about 45w TEC's have you !!! They won't work for your project.