• The plate recuperator consists of cross-shaped plates, between which isolated supply and exhaust air flows are flowing across and in parallel and their temperature equalises.
• The advantage of the plate heat exchanger recuperator is very high efficiency of separation of exhaust and supply air – up to 99.9%.
• Thus, it can be used to recover heat even from the warm air flowing out of the kitchen exhaust channel without worrying that unwanted smells will spread in other areas of housing.
• This type of recuperator does not recover the humidity in the room.
• In cases where the outdoor air is very dry, humidity levels in the room will also decrease.
• The disadvantage of a plate recuperator is the possible formation of condensate in the heat exchanger itself.
• This may occur during the winter period, when the outdoor air temperature drops below -2°C.

There are two solutions that are used to prevent condensate formation:

1. to reduce the air supply intensity and to increase the air exhaust intensity, thereby reducing the efficiency of the recuperator and reducing the supply air temperature.
2. to install an electric heater in the outdoor air supply channel and to heat outdoor air above -2°C, but this will result in additional electricity consumption.

• An aluminium plate rotor containing air flow channels is installed on bearings in the ventilation unit with a rotary heat exchanger. The exhaust air heats up the rotor and this heat is used to heat the supply air.
• In this type of equipment, supply and exhaust air are slightly mixed – 2% to 5%.
• Thus, there is a minimal possibility of transmitting odours from exhaust air to supply air.
• The rotary heat exchanger partially recovers humidity from exhaust air, which is important during the winter period when the relative humidity of the outdoor air is low.
• There is no possibility of condensate formation in the rotary heat exchanger, which eliminates the risk that the equipment may freeze.
• It should be noted that at very low outdoor temperatures the effectiveness of this type of recuperator will reduce.

• An enthalpy heat exchanger has been created to combine the good properties of a plate heat exchanger and a rotary heat exchanger.
• The enthalpy heat exchanger basically is a plastic plate heat exchanger.
• Its plates are made of a special nanomembrane, the main property of which is the recovery of humidity.
• The membrane structure is designed so that only compounds that are the size of water vapour molecules can move from one side of the membrane to the other.
• The enthalpy heat exchanger has a high energy recovery efficiency.
• Due to the nature of the recovery of humidity, the risk of freezing of the heat exchanger reduces significantly.
• Such a recuperator allows the air humidity level in the rooms to be maintained at the same time and guarantees that the supply and exhaust air flows are separated from each other.