Work Performed: Responded to a no hot water call for a Rheem tankless water heater installed in 2021 by another company. Results: Upon arrival, the unit was functioning normally. Each time hot water was turned on, the tankless unit fired up and delivered hot water as expected. Repeated the test five times — the unit consistently responded and produced hot water. Inspected the drain lines, air intake, and exhaust for blockages — all clear. Checked the water filter — no issues found. Flame sensors were not accessible for inspection, but the burner ignited and ran properly during testing. No error codes were present, and there is no way to recall past error codes on this model. At this time, the unit is operating normally, and no fault could be found during the visit.