I have over 10 antminer S9 Bitcoin miners for sale. They are not the current most powerful miner but work well. 13.5TH/s, run on 120v or 220v.
I was using these to heat my home while mining for bitcoin. When incorporating the cost to heat my home over the winter, these are still profitable. If you have a spare dryer outlet or spare heat coil outlet, you can easily run 5-8 of these.
Could also do an immersion cooling setup and dump heat to the outside or to a DHW setup.
Contact with any questions, will make a deal for anyone looking to buy them all.