If living in an area that gets cold during the winter an Avalon A841 works great as a space heater. Throttled down to 9THs and fan limited to 40% it's nice and quiet while pulling about 750w.
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This is the best bet - Canaan Avalon A8 - rather than the S9.
Way more reliable, and uses original firmware, you don't have to work out how to hack in an after market firmware that can also charge you 2%
Getting an old, working, not overclocked and due to die soon, S9 is a crapshoot.
I run an A851 a couple of meters behind me (it's winter now) 24/7 as a heater - it's low pitch quiet enough 9TH/s