Open vs. Closed Condensate Recovery
Condensate recovery systems can be divided in two categories: open recovery systems and closed recovery systems. The following article offers details on how to select one or the other.
Difference between Open and Closed Condensate Recovery
Open condensate recovery refers to a system where the condensate becomes exposed to the atmosphere at some point during the recovery process, which results in condensate with a maximum temperature of 100 ºC. These systems typically use positive pressure or a mechanical pump to circulate condensate. The benefit of this type of system is that its construction is fairly inexpensive, so it is relatively easy to implement.
In closed condensate recovery systems, condensate does not come in direct contact with the surrounding atmosphere. Condensate circulates with the help of motorized pumps. In such systems, condensate remains pressurized during the entire recovery process. High temperature condensate of over 100 ºC can therefore be recovered, which means that a much greater amount of heat can be retrieved than in an open system.
Which is more suitable: open recovery or closed recovery?
Two factors are usually used to determine the suitability of an open or closed condensate recovery system:
- Condensate recovery ratio
- Condensate pressure
Optimal Conditions for Open and Closed Condensate Recovery
Click the buttons on the right side of the graph to highlight optimal conditions for each type of condensate recovery*.
*’Positive pressure condensate recovery’ is a subcategory of open condensate recovery.
Summary Table
| Open Recovery | Closed Recovery | |
| Recovery Temperature | 100 ºC [212ºF] maximum | 180 ºC [356ºF] and above* |
| System Configuration | Simple | Complicated |
| Initial Costs | Low | High |
| Running Costs | Depends on the system | Depends on the system |
| Piping Corrosion | Significant (condensate comes into contact with air) | Slight (no contact with air) |
| Vapor Clouds | Large amounts (if condensate temp. is high) | Minimal amount |
| Recovery Applications | Feed water tank Hot water heating source Water for cleaning |
Mainly for direct feed to boiler |
*Limited by max operating temperature of pump and peripheral equipment
