The principle behind heat recovery ventilation is to continuously supply fresh air & extract stale air, so that the air in the house is changed around ten times per day. Air is supplied to living areas (bedrooms living room) and extracted from service or wet rooms (bathrooms, kitchen, utility).
At the heart of the ProAir Heat Recovery Ventilation system is the counter-flow plate exchanger.
This cleverly designed array of plastic plates with a warm and cold flow over every second plate, has the highest surface-area contact between the two flows of any of its type. The plates are designed so that the air flows in tiny triangular ducts where every warm triangle is surrounded by three cold triangles and vice versa. It gets its high efficiency, not just from this, but also due to the fact that the air flows uniformly and smoothly through the channels in a laminar flow pattern.