Pride Plumbing was called out for a Rinnai RL75i tankless water heater that would stop producing hot water within 5 to 10 minutes of use. We checked the unit's inlet screen, flow rate, and heat exchanger temperature and found nothing wrong. We then called Rinnai tech support, and through them we ran multiple diagnostics and found nothing wrong. They then recommended we check the fan and vent for debris which we did, but we did not find any. Finally, they recommended we check the gas pressure when the outside temperature was warm in the afternoon to see if the water volume drops, and if it does, to have the homeowner contact a gas company to come out and investigate it.