Came out today to conduct a propane to nat. Gas conversion on the tankless water heater and we also changed out the other conventional water heater from a propane to a natural gas tank water heater. (40 gal. Tall) all went well we tested the tankless and was producing hot water but sometimes on the tankless if it senses an air pocket in the gas flow it can turn off and throw a code. In this case all would need to be done is to unplug and plug unit back in and push the power button.