
Steam Valve Fail Position – NC or NO? Let’s Clear the Confusion!
In HVAC steam applications, choosing the right fail-safe position of a control valve isn’t just about specs—it’s about safety, performance, and purpose.
So, what’s the ideal fail position for a steam control valve?
Fail-Closed (Normally Closed) is the industry standard.
It ensures steam stops flowing when power or control signal fails—avoiding overheating, conserving energy, and protecting equipment.
Used widely in:
AHUs
Heat exchangers
Radiators
Humidifiers
Fail-Open (Normally Open)? Use only for critical systems that require continuous steam flow, like:
Freeze protection
Hospital sterilizers
Critical process zones
The decision isn’t random—it’s driven by application needs and safety logic.
Engineering Tip: Always match your valve fail position with the risk and recovery logic of the system!