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- This design is ideal when the supply and exhaust ducts are far apart or on different floors. Because the coils are separate and connected only by piping, installation flexibility is much higher than with plate or wheel exchangers.
- Exhaust air coil (finned tube) Supply air coil (finned tube) Circulation pump Expansion tank and glycol-water mixture Controls and temperature sensors
- Pros: No risk of cross-contamination Works over long distances Easy to retrofit into existing ductwork Can recover heat from multiple exhaust points Cons: Lower efficiency than counter-flow plate or rotary wheels (typically 40–60 %) Requires pump power and maintenance Glycol solution must be checked periodically
- Kitchen and laboratory exhaust Multi-zone commercial buildings Industrial processes with remote exhaust stacks Swimming pools and locker rooms
- What glycol concentration is typical? A 30–50 % propylene glycol solution is common, depending on freeze protection requirements. Can run-around coils recover humidity? No. They are sensible-only systems and do not transfer moisture.
A bobina de recorrido heat recovery system uses two finned coils connected by a closed glycol loop. A pump circulates the fluid between the exhaust coil, where it picks up heat, and the supply coil, where it releases heat into the incoming air.
This design is ideal when the supply and exhaust ducts are far apart or on different floors. Because the coils are separate and connected only by piping, installation flexibility is much higher than with plate or wheel exchangers.
- Exhaust air coil (finned tube)
- Supply air coil (finned tube)
- Circulation pump
- Expansion tank and glycol-water mixture
- Controls and temperature sensors
Pros:
- No risk of cross-contamination
- Works over long distances
- Easy to retrofit into existing ductwork
- Can recover heat from multiple exhaust points
Cons:
- Lower efficiency than counter-flow plate or rotary wheels (typically 40–60 %)
- Requires pump power and maintenance
- Glycol solution must be checked periodically
- Kitchen and laboratory exhaust
- Multi-zone commercial buildings
- Industrial processes with remote exhaust stacks
- Swimming pools and locker rooms
What glycol concentration is typical?
A 30–50 % propylene glycol solution is common, depending on freeze protection requirements.
Can run-around coils recover humidity?
No. They are sensible-only systems and do not transfer moisture.