目次
- Frost needs two things: sub-freezing supply temperature and moisture in the exhaust. A typical case: exhaust at 20 °C and 40% RH, outdoor air at −10 °C. As the exhaust cools toward the supply outlet it can reach −5 °C, well below freezing, and the condensed moisture ices onto the plates. Effectiveness above ~70% in deep cold raises frost risk. High indoor humidity (pools, labs, kitchens) makes it worse. Frost shows first at the cold corner of the plate pack.
- Method How it works Trade-off Preheat supply inlet Warm outdoor air before the core Most reliable; uses energy Exhaust bypass / recirculation Waste part of recovery to keep plates warm Simple; lowers seasonal effectiveness Periodic defrost (wheels) Reverse rotation or purge to melt ice Not for plates; brief loss of recovery Heat-pipe assist Heat pipe pre-warms supply near the cold corner Passive; adds cost and depth For a plate exchanger, preheat at the supply inlet is the standard fix because plates have no moving parts to reverse. A rotary wheel can instead use a purge and periodic defrost cycle.
- Size the core for the design winter temperature, then add 10–15% face area so the bypass or preheat strategy has room to work without starving airflow. Our sizing guide walks through the calculation, and the kitchen recovery example shows the same logic on a warm-side load. Designing a cold-climate exchanger? EN159 supplies plate, rotary, heat-pipe and counterflow air-to-air exchangers with frost-protection options sized to your winter design conditions. Send outdoor and exhaust temperatures, humidity and airflow. Request a quote
- Air-to-Air Heat Exchangers · Heat Recovery Units · Plate Heat Exchanger Guide
In cold-climate ventilation, an exhaust-to-supply air-to-air plate exchanger can frost on the exhaust side when the supply outlet drops below the dew point of the humid exhaust. Frost narrows the channels, raises pressure drop and eventually blocks the core. Knowing when it forms — and which protection strategy to use — keeps the unit efficient through winter.
Frost needs two things: sub-freezing supply temperature and moisture in the exhaust. A typical case: exhaust at 20 °C and 40% RH, outdoor air at −10 °C. As the exhaust cools toward the supply outlet it can reach −5 °C, well below freezing, and the condensed moisture ices onto the plates.
- Effectiveness above ~70% in deep cold raises frost risk.
- High indoor humidity (pools, labs, kitchens) makes it worse.
- Frost shows first at the cold corner of the plate pack.
| Method | How it works | Trade-off |
|---|---|---|
| Preheat supply inlet | Warm outdoor air before the core | Most reliable; uses energy |
| Exhaust bypass / recirculation | Waste part of recovery to keep plates warm | Simple; lowers seasonal effectiveness |
| Periodic defrost (wheels) | Reverse rotation or purge to melt ice | Not for plates; brief loss of recovery |
| Heat-pipe assist | Heat pipe pre-warms supply near the cold corner | Passive; adds cost and depth |
For a plate exchanger, preheat at the supply inlet is the standard fix because plates have no moving parts to reverse. A rotary wheel can instead use a purge and periodic defrost cycle.
Size the core for the design winter temperature, then add 10–15% face area so the bypass or preheat strategy has room to work without starving airflow. Our sizing guide walks through the calculation, and the kitchen recovery example shows the same logic on a warm-side load.
Designing a cold-climate exchanger?
EN159 supplies plate, rotary, heat-pipe and counterflow air-to-air exchangers with frost-protection options sized to your winter design conditions. Send outdoor and exhaust temperatures, humidity and airflow.
Air-to-Air Heat Exchangers ·
Heat Recovery Units ·
Plate Heat Exchanger Guide
