The average time on an initial assessment is 1 hour or less, depending on the environment the geyser was installed in.   Geyser replacement can range from 2 to 6 hours for the replacement of the tank alone – depending on the size of the tank, the time it takes to drain and prepare the old geyser for removal and re-installation of the new.   The surrounding reconnection of pipes, fittings and services will vary depending on the position of the geyser, as well as the time it takes to fill the geyser up before it can be re-commissioned with electricity to enable the heating process.