I would agree with philipma1957, get an S7 and downclock. This will still give you a decent hashrate and low enough power draw that you should be safe with anything that has fairly recent wiring (within the last 20 years). This would also be somewhat quiet, the power supply might be loud depending on what you use. Also depending on the size of the apartment heat might become an issue for you. You are essentially talking about running an 800watt heater all the time.
It also means that you'll use less money on heating this year if you live in a cooler place in the northern hemisphere- although miners don't provide the best heating, they do make a room nice and toasty in just a few minutes. You can always underclock a miner for less heat production if needed.
