Arrived on site to perform an annual tune-up on a Viessmann propane boiler and tankless water heater. The water heater is high voltage electric and we don’t service them. Performed annual tune up on a Viessmann propane boiler, cleaned the burner, heat exchanger, igniter, flame sensor, and condensate trap. Inspected the expansion tank, neutralizer, combustion, venting, and overall hydronic system operation. Replaced leaking relief valve and piped it to within 6 inches of the floor. Bubble-tested the gas line and checked carbon monoxide levels; no leaks were found. Verified proper operation, and the system is working correctly at this time.