Is an aquastat required as part of a tankless domestic hot water system?

Is an aquastat required as part of a tankless domestic hot water system?

• A. False
• B. True
• C. Not applicable
• D. Depends on model

Answer: (B)

An aquastat is the temperature-control device that signals the heat source to start or stop based on the water temperature. Even though a tankless domestic hot water system heats water on demand and doesn’t store hot water, it still must regulate the heat source to deliver water at a safe, consistent temperature as flow changes. The unit (or its internal controls) uses sensing and switching to fire the burner when cold water enters and shut it off when the desired outlet temperature is reached. That temperature-control function is why an aquastat (or an equivalent control) is considered required for a tankless DHW system.

An aquastat is the temperature-control device that signals the heat source to start or stop based on the water temperature. Even though a tankless domestic hot water system heats water on demand and doesn’t store hot water, it still must regulate the heat source to deliver water at a safe, consistent temperature as flow changes. The unit (or its internal controls) uses sensing and switching to fire the burner when cold water enters and shut it off when the desired outlet temperature is reached. That temperature-control function is why an aquastat (or an equivalent control) is considered required for a tankless DHW system.