Table des matières
- Factor Air-to-Air Air-to-Water Streams Two air ducts Air + water/glycol loop Distance Short (cores co-located) Long (piping carries heat) Cross-contamination None (plate/pipe) None (closed loop) Reuse options Pre-heat supply air Air, water heating, process Complexity Low Higher (pump, expansion tank) Cost Lower Higher
- Exhaust and the heat sink are on different floors or buildings. You want to heat domestic water or a process, not just air. Multiple exhaust points feed one loop.
- Supply and exhaust are side by side. You only need pre-conditioned make-up air. Budget and simplicity are priorities.
- Can I combine both? Yes. Air-to-air handles the main recovery; an air-to-water loop serves remote or water loads. Which is more efficient? Air-to-air is usually a few points higher because there is no pump and fewer transfer steps.
Heat recovery comes in two broad forms. Air-to-air exchangers move heat directly between two air streams. Air-to-water devices (like run-around coils or exhaust water heaters) transfer heat into a fluid loop that can serve distant or mixed loads.
| Factor | Air-to-Air | Air-to-Water |
|---|---|---|
| Streams | Two air ducts | Air + water/glycol loop |
| Distance | Short (cores co-located) | Long (piping carries heat) |
| Cross-contamination | None (plate/pipe) | None (closed loop) |
| Reuse options | Pre-heat supply air | Air, water heating, process |
| Complexity | Low | Higher (pump, expansion tank) |
| Cost | Lower | Higher |
- Exhaust and the heat sink are on different floors or buildings.
- You want to heat domestic water or a process, not just air.
- Multiple exhaust points feed one loop.
- Supply and exhaust are side by side.
- You only need pre-conditioned make-up air.
- Budget and simplicity are priorities.
Can I combine both?
Yes. Air-to-air handles the main recovery; an air-to-water loop serves remote or water loads.
Which is more efficient?
Air-to-air is usually a few points higher because there is no pump and fewer transfer steps.