How can I keep my cylinder warm in case of a power cut? Comments Off on How can I keep my cylinder warm in case of a power cut? 18 Jan 2016 Vote Up 0 Vote Down Answered Public Public Private Electric Water Cylinders Anonymous asked January 18, 2016 Hi, How can I keep my cylinder warm in case of a power cut? 1 answer Vote Up 0 Vote Down Public ⋅ January 19, 2016 On a new hot water cylinder the cylinder will stay hot for 24 hours. Everytime you use hot water in that period it introduces cold water in to the tank which cools it. #1 Please login or Register to Submit Answer