Unit shuts off when multiple fixtures are used; hot water stops unexpectedly under high demand

Safety first: None beyond normal; this is an operational limitation issue.

Steps to check:

• Reduce simultaneous use: Limit the number of hot water fixtures running at the same time and see if the problem disappears.
• Check gas supply: Ensure gas piping and meter are sized for the heater's maximum input and other appliances.
• Review sizing: Compare your heater's capacity (GPM at your inlet temperature) with actual household demand.

When to call a professional: A contractor may need to upsize the gas line or install additional capacity if the unit is undersized.