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how does heat recovery ventilation work?

Heat recovery ventilation appliances offer the optimum solution for systematic, energy-saving ventilation of new homes and renovation projects.

A ventilation appliance is usually mounted in your plant room, utlity or loft area, connected via ductwork to ceiling terminals. One fan extracts stale warm air through these terminals from your wet rooms (kitchens, bathrooms etc) and takes it to the ventilation appliance to be exhausted outside.

exhaust air flow of heat recovery ventilation

Meanwhile, another fan draws fresh filtered air from outside and supplies it through ceiling terminals in the habitable rooms of your home (bedrooms, dining rooms, studies, living rooms).

fresh supply air flow in heat recovery ventilation

During this process, a heat exchanger within the appliance transfers up to 95% of the heat from the outgoing stale air to the incoming fresh air, meaning whilst you get a whole house air-change every two hours, you save about a third on your heating bills.

heat recovery ventilation air flows

In warmer months, the heat recovery process can be automatically bypassed to ensure that cooler fresh air still enters the home, but without recovering the heat, thus reducing humidity level and perceived temperatures by about two degrees.

what is a heat exchanger?

A heat exchanger consists of several metal plates. Both airflows (fresh air and stale air) pass over these plates, but on different sides. As the airflows are hermetically separated, they do not mix. The heat is transferred through the plates from the stale warm air, to the cool fresh air side.

The heat exchangers in the units we specifiy are constructed out of seawater-resistant aluminium for maximum heat exchange and durability.

cross flow and counter current heat exchangers

Some heat recovery ventilation systems use a CROSS-FLOW heat exchanger, which can only achieve heat recovery efficiencies of up to 75%. As you can see, some heat from the stale air is always wasted.

However, all our appliances use COUNTER-CURRENT heat exchangers, which can reach efficiencies of up to 95%. As you can see, almost all heat is extracted from the stale air, ensuring you the very best in heat recovery efficiency.