How long does a instantaneous hot water install take? Comments Off on How long does a instantaneous hot water install take? 18 Jan 2016 Vote Up 0 Vote Down Answered Public Public Private Gas Water Heating Anonymous asked January 18, 2016 Hi, How long does a instantaneous hot water install take? 1 answer Vote Up 0 Vote Down Public ⋅ January 20, 2016 It can take 4-6 hours for a typical install. #1 Please login or Register to Submit Answer