I have a gas tankless hot water heater. the pilot frequently shut off. The gas valve control is controlled by water flow. When there is hot water runs, the water creates a pressure discrepancy at two sides of valve so the gas is on. I do not like this kind design because it is not reliable. about every three years the value needs replaced. It has been replaced twice by me and a plumber. I would like to replace it with a new tankless gas hot water heater with electrical gas lighting. Any suggestion.