All the time? That's very inefficient, especially when running your boiler outside heating season and without a vacuum flask.

The actual solution is to boil small quantities of water. I can boil one cup in 90 seconds or so, even with the 120v handicap.

Or boil a larger quantity and fill it into a thermos. Perfectly fine for instant coffee throughout the day. (And without the coffee stains in the thermos.)

Sure, but efficiency wasn't the goal here. Anyway I use hot water enough (~6-10 times daily) that I don't mind spending extra for it