The more I think about this the more I think there could be a real business model here. Make a device that looks and acts like a space heater but is in fact a miner loaded with your private keys. Market it as a "smart heater" that requires a wifi connection to operate. Sell it as a loss leader, or maybe even give it away for free. It doesn't have to be state-of-the-art hardware, so it can be cheap to make. Hmm...