Yup, the front half of my house has been considerably warmer these last couple days. Partly because temps outside are 10 degrees warmer, and partly due to the big number cruncher in the corner of the living room. I don't need the AC on, it's just warming the house to about 72 * F. Perfect.
I'm paying $0.12 per kw/hr. This thing is chewing up right around 700 watts, let's call it $0.10/hr. $2.40/day, about $72/month.
I need a return of at least 2 LTC to make that worthwhile.
Right now, I'm earning about 0.05 to 0.06 LTC per block solved by my pool, and my pool is "supposed" to solve a block about once every 5.5 hours. The last couple days have seen some atrociously long periods with no solved blocks... but there have been some short-solves a few days before that. It'll even out. I'll get about 0.25 LTC per day, as long as it does.
That should give me about 7.5 LTC per month. 2 to pay the bill, 5.5 to cover the hardware investment.
Of course, come summertime, I'll need to re-appraise. Mining is actually saving me from having my heat pump turn on to warm the house in winter. But in the summertime it will obviously cause increased AC use. Perhaps I'll only mine at night, when our electric rates are less expensive and the temps outside are lower.