Die dew point<\/strong> 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.<\/p>\n Below 0 degC the same limit is the frost point<\/strong>: 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.<\/p>\n 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<\/a> matters: northern sites need defrost or frost-tolerant cores, not just a high nominal effectiveness.<\/p>\n Protection strategies – purge sectors, preheat, bypass – are covered separately under frost protection in heat recovery systems<\/a>.<\/p>\n Is frost point always below dew point?<\/strong> For the same moisture content, yes – frost forms at a lower temperature than condensation because ice has lower vapour pressure than liquid water.<\/p>\n Do plates frost as badly as wheels?<\/strong> Plates can frost too, but a motorised bypass is simpler to apply than wheel regeneration.<\/p>\nFrost point: where ice appears<\/h2>\n
Why this bounds the design<\/h2>\n
Related reading<\/h2>\n
Frequently asked questions<\/h2>\n