Comfort S 13 Bosch Tankless Water Heater

[DouglasMiller]

When I turn water on there is no spark to ignite gas. If I tap fairly hard on small vented area where spark should be and where gas should ignite, spark starts and flame comes on??

 

[John Gayewski]

When I turn water on there is no spark to ignite gas. If I tap fairly hard on small vented area where spark should be and where gas should ignite, spark starts and flame comes on??

Sounds like a loose connection or one that's about to break.