Clean the hot water delivery system. Flushed and descaled a Rheem tankless hot water heater. Model #Rtgh-95dvn, serial #Rhln0411j00477. Upon arrival I powered the system down and shut off the incoming and outgoing water. I connected the hose to from the cleaning system to the hot water heater. Filled the cleaning system with water and descaling solution. I let the system run the cleaning solution through the hot water heater for 30 minutes. After 30 minutes I removed the cleaning solution and allowed clean water to rinse the system. Once I ensured the system was clean I opened the incoming and outgoing water and powered the system back up. The system is operating properly at this time. Service was pre paid for.