The house we're buying currently has an oil burner (no mains gas) linked to a hot water storage tank. I have only ever known gas combi boilers and don't like the idea of running out of hot water. The oil boiler requires replacing either way but was thinking about swapping it out for an oil combi. Do they operate the same as a gas combi? i.e. the water takes the same length of time to heat up? Any help appreciated, cheers.