Commercial plumbing repair. Check tub area for noise and hot water is not as hot when you first run the tub. Found 2 shower mixing valves crossing over, replace tub and shower cartridges. Noise in return line on the tankless heater when it is running. Drained to let air chambers refill with air. Check water softener found no water in brine tank clean screen and brine valve regenerate softener to let cycle through steps. Pull turbine on softener and cleaned water softener.