Performed diagnostic residential gas water heater Checked gas pressure pre and post gas valve No error codes Tankless rescaling was performed on prior visit 11 yr old tank no records of service Per tech support reccomendation cleaned burners and housing insects and debri Cleaned fins on heat exchanger Reassembled all components Reset gas pressure to proper working pressure This cleaning is an attempt to fix fluctuation in hot water No warranty on any existing plumbing If problem persists recommend replacement of tankless unit Left option to replace unit