This question can be answered with a close reading of the text itself. Granted, John is describing these appliances with eyes that have no idea what they are; but, if you read closely and piece together the information based on appliances that you know, it is pretty easy to guess what they were. One appliance that he runs across he describes as this:
"There was a cooking-place but no wood, and though there was a machine to cook food, there was no place to put fire in it."
This, if you think about it, was probably an oven. Ovens cook food, but there is no "fire" as John and his people had to use, in order to cook. He also runs across electric lamps, and says that they looked like lamps but "had neither oil nor wick." He also runs across a bathtub, and describes how there was a knob that said "hot" and a knob that said "cold," but how there was no water there. He concludes that the gods must have "washed in air." The kitchen sink has the same concept, and baffles him a bit.
Through his journeys, John runs across many remnants of ancient civilization, appliances being just one of them. He runs across ruined subways, old boxed and canned foods, and the survivors of abandoned house pets. If you read closely and piece together the clues, you can figure out what these things are. I hope that helped; good luck.