Not sure how long. My husband put water in the incubator yesterday. I looked in there this morning, and one egg was crushed by the jiggler, and the top was off. It was cold last night.
There's no way of knowing if the embryos survived, but generally they can often survive periods of low temperatures and be fine afterwards. They may hatch later than usual. Agree with sourland that you should continue incubating as normal and candle in about two more days