I run a single S17 (~2400W) in my well-insulated garage at a time, which is enough to keep it nice and toasty in there all winter long.
Initially, I'm not looking to keep the garage "nice and toasty", I'd just like to keep it above freezing. If I can get any noticible temperature difference at all, then I'll consider spending more money and getting more equipment. If I can't even get a noticeable difference with $500 of equipment, then it probably isn't going to be worth it to spend more.
But it is also loud enough to hear on the street, so keep that in mind. People have posted various ways of modifying S9s to take them down to a tolerable noise level, but it usually involves running them at lower clock rates so they use even less power, maybe 700W max.
Noise isn't too big of a concern at this point. I suppose if my wife can hear it all the way in the house, or if the neighbors complain then I'll have to re-consider.
If you don't care about the noise, then 2 S9s running full speed for a combined 2400W or so would probably be good to keep your garage warm, but that's most likely going to cost you $1000 for two miners that could be 4 years old...
That's a bit more expensive than I was hoping. Perhaps I'll have to wait a few more years and then look into it again.
S9s might get cheaper if the BTC price tanks some more... another 50% drop or so and the break-even power cost for an S9 will be under 7c/kwh.
Yeah, also if newer/better equipment comes along then the older equipment might get cheaper. I'm in no hurry. I guess I'll just keep an eye on things and take this time to learn a bit more.
What is your power cost?
Doesn't really matter, since I'm not trying to make a profit.
Extreme examples:
If my power cost were $0.50/kWh
A 1500 watt space heater would cost me $504 to run continuously for 4 weeks.
Meanwhile, a 1500 watt PSU running a miner that earns 0.000003 BTC (300 satoshis) per day would generate the exact same heat and would use the same $504 of electricity BUT would offset it's cost of operation by generating about $4.12 worth of bitcoin over that same period of time. I save $4.12 every 4 weeks by buying and running mining equipment instead of buying and running an electric space heater.
If my power cost were $0.01/kWh
A 1500 watt space heater would cost me $10 to run continuously for 4 weeks.
Meanwhile, a 1500 watt PSU running a miner that earns 0.000003 BTC (300 satoshis) per day would again generate the exact same heat and would use the same $10 of electricity BUT would still offset it's cost of operation by generating about $4.12 worth of bitcoin over that same period of time. I still save $4.12 every 4 weeks by buying and running mining equipment instead of buying and running an electric space heater.
Since the goal and purpose of the equipment is to generate heat, the bitcoins generated are effectively free. Therefore, regardless of my power costs, I come out ahead by the amount of bitcoin that the heater (I mean miner) generates.