Please place your miners somewhere where the heat comes to good use.
Make a deal with a friend that doesn't have "free" heating!
There is no such thing as a free lunch, at some point you will have to pay for your "fjarrvarme" (steam that comes through a pipe from a factory or garbage burning / gas plant)
It's just too loud to have inside. Think of your health, too. Constant noise introduces unhealthy levels of stress.