Pretty loud space heater:)
Most all the asic's I have reviewed I had in my room during initial testing. Once I got a mining area it changed as I have 240 there and only 120 in my room. But I did use many as space heater's.
That being said it is so much nicer to have them all in one place in my mining area. Not juggling so many on each circuit being safe. And putting them in mining area I got rid of noise around house. So you definitely can use them as space heater's I have but once you get into some of the big miner's it's nice not to.
Also if you have someone over who is not familiar with bitcoin's it's nice not to have them see these asics all over. For example when I had fiber installed was not so fun moving miner's or hiding them for a few hour install. Also a electrician seeing my miner's was the cause of the most outrageous electrical quote I ever got, just as he saw these machines that seemed weird to him.