Seriously Mike? People will use miners for heat? Man for a smart engineer you sure say some pretty stupid things.
I use the waste heat from mining as a product as well. Right up until now my mining has at least broken even with power costs AND produced bitcoins that I can spend (on more heat if I wanted). So because I get the heat (100% efficiency electric heating) and I get at least as much money back as I paid on heat, you could easily say that it's over 200% efficient.
Right. But Mike said people would keep doing what you're doing despite there being no profits in mining. Would you still mine purely for heat? Of course not. What a retarded thing to suggest.