fourth year
An electronic relighter, which senses a pilot failure and relights it before the safety unit can trip off, can be retrofitted to a water heater without modifying any of the current safety devices. The reason not to do it is that the cost would be about the same as a new water heater. If you are concerned about using a match to light the pilot, many manufacturers make heaters with Piezo push button ignitors such as are on BBQ units. Any electronic device would require an electrical circuit to the water heater.
