Not at all you set your electric geyser to max temperature and make sure it switches off when drawing from the grid. Take hot water outlet from electric geyser and feed that through a temping valve set at 55 and then into cold water inlet of gas geyser that way with an intelligent gas geyser it only has to heat it by 5 degrees obviously once the water in electric geyser drops below 55 the gas geyser works a little harder however it will save a lot as chances are you will never be heating water from ice cold.