I have two 1500w internal, no weld, elements. One is straight plugged in, and the other is on a SCR motor controller with the SCR on a MUCH larger heatsink. 2000w max must mean the damn thing is in chilled oil!! Even at 1500w, at mid-power, the heatsink on it cooks. I would look up even a higher power one, so you are well within the low-mid end of the rating scale.

My boiler is 25l.