What You Are Selecting
A heat pipe exchanger is a bundle of sealed tubes with a working fluid. It transfers sensible heat passively - no motor, no airstream mixing. Effectiveness is lower (50-65 percent) but reliability is very high.
Key Selection Parameters
- Tube bundle size - more tubes and surface area raise capacity
- Working fluid - chosen for the operating temperature range
- Orientation - evaporator end must sit in the hot stream, condenser in the cold
- Fin spacing - tighter fins improve transfer but foul faster
Sizing Approach
Estimate the sensible load to recover, then size the bundle so the temperature lift stays within the fluid's effective range. Heat pipes are often used where a failed moving part would be costly.
Best-Fit Applications
- Remote or harsh environments
- Industrial extracts where reliability beats peak efficiency
- Any space where zero cross-contamination is mandatory
Verify
Confirm the rated effectiveness at your airflow and the fluid's temperature limits; heat pipes do not recover moisture.
Before You Start
A successful Heat Pipe Heat Exchanger Selection Guide project begins with measurement. Record the supply and exhaust airflow rates, the temperatures on each side, and the hours the system runs per year. Note any contaminants in the exhaust and the available space for the core and ductwork. These figures decide both the type of exchanger and whether the payback makes sense.
Step-by-Step
First, choose the exchanger type from the air cleanliness and recovery target. Second, size the core using the measured airflow and the log-mean temperature difference, leaving margin for fouling. Third, lay out the duct path so the exhaust is filtered before the core and the supply side has drainage if it may condense. Fourth, add a bypass for free cooling and wire the fans to a simple control. Finally, commission the unit and record baseline temperatures.
Verification
After startup, compare the pre- and post-installation supply temperatures at the same outdoor condition. A steady recovery of 50 percent or more confirms correct sizing. Re-check each season and clean the exhaust side when the recovered temperature begins to fall, because fouling quietly erodes performance over time.
Frequently Asked Questions
Do I need a bypass? In most climates yes, so the system can free-cool when outdoor air is mild. How is sizing done? From measured airflow and the log-mean temperature difference, not from estimates.