In Russia they are actually taking advantage of the heat produced by miners, and they have built water cooled Bitfury-based miner (Sunrise series).
So those miners are not only mining btc, but also working as 'water boilers'.
Ja. As I've brought up before, I'd think miners supplying heat for thermal pool spa's would be a great way to go. Beats using only gas or electric as direct heat!
It would be a really nice project to grab some old Ant C1's, then upgrade them with some Hotmine (Bitfury 16nm) boards and hook them up to a bath tub via a heat exchanger.

Few of those and you could even build a spa resort for people interested in Bitcoin.
If anybody is interested, you are free to use this as a business idea.

And if a mistake occurs, the customer gets electrocuted lol?? Yes, it is unlikely to occur but lapses do occur. It will be ok to do in a home setting I guess but laws in a commercial setting would prevent water being too close to electricity I would think. I suspect it wont pass safety standards in my country though. Juz my 2 cents thoughts anyways, not tryin to be disagreeable