Table of Contents
- The dew point is the temperature at which air, cooled at constant pressure and humidity, becomes saturated and water begins to condense. If a recovery core surface drops below the exhaust dew point, condensate forms on it - normal in cooling duty, a design input for drainage.
- Below 0 degC the same limit is the frost point: moisture deposits as ice instead of liquid. In cold-climate ventilation the exhaust airstream can sit below freezing while the supply is also cold, so the core can ice up and block airflow.
- Recovery only works while the core is open. Once frost bridges the channels, effectiveness collapses and fan power spikes. That is why climate-based selection matters: northern sites need defrost or frost-tolerant cores, not just a high nominal effectiveness.
- Protection strategies - purge sectors, preheat, bypass - are covered separately under frost protection in heat recovery systems.
- Is frost point always below dew point? For the same moisture content, yes - frost forms at a lower temperature than condensation because ice has lower vapour pressure than liquid water. Do plates frost as badly as wheels? Plates can frost too, but a motorised bypass is simpler to apply than wheel regeneration. Need help specifying the right air-to-air heat recovery for your project? Contact the QIYU engineering team - WhatsApp +86 157 5335 5505, or email kuns913@gmail.com. Frequently Asked Questions Why is dew point the critical temperature for a recuperator? When the colder exhaust falls below the incoming air's dew point, moisture condenses on the core; below 0 degrees C it can frost and block the passages, so dew and frost point set the defrost or bypass strategy. How do you protect a core in freezing climates? Use frost-suppression methods such as preheating the supply air, recirculation or bypass of part of the exhaust, or wheel frost-control purging so the leaving-exhaust temperature stays above freezing.
The dew point is the temperature at which air, cooled at constant pressure and humidity, becomes saturated and water begins to condense. If a recovery core surface drops below the exhaust dew point, condensate forms on it - normal in cooling duty, a design input for drainage.
Below 0 degC the same limit is the frost point: moisture deposits as ice instead of liquid. In cold-climate ventilation the exhaust airstream can sit below freezing while the supply is also cold, so the core can ice up and block airflow.
Recovery only works while the core is open. Once frost bridges the channels, effectiveness collapses and fan power spikes. That is why climate-based selection matters: northern sites need defrost or frost-tolerant cores, not just a high nominal effectiveness.
Protection strategies - purge sectors, preheat, bypass - are covered separately under frost protection in heat recovery systems.
Is frost point always below dew point? For the same moisture content, yes - frost forms at a lower temperature than condensation because ice has lower vapour pressure than liquid water.
Do plates frost as badly as wheels? Plates can frost too, but a motorised bypass is simpler to apply than wheel regeneration.
Need help specifying the right air-to-air heat recovery for your project? Contact the QIYU engineering team - WhatsApp +86 157 5335 5505, or email kuns913@gmail.com.
Frequently Asked Questions
Why is dew point the critical temperature for a recuperator?
When the colder exhaust falls below the incoming air's dew point, moisture condenses on the core; below 0 degrees C it can frost and block the passages, so dew and frost point set the defrost or bypass strategy.
How do you protect a core in freezing climates?
Use frost-suppression methods such as preheating the supply air, recirculation or bypass of part of the exhaust, or wheel frost-control purging so the leaving-exhaust temperature stays above freezing.