Why are you using fahu recovery wheel?

FAHU is used to conserve energy by interchanging the enthalpy of the air coming from corresponding higher or lower temperature regions of the building.

The basic idea of using FAHU (Fresh Air Handling Unit) recovery wheel is to utilize & recover the maximum amount of cooling that is expelled through the exhaust air. This addresses less wastage of cooling energy & reduces the input electrical power to a significant number; that could have been consumed in cooling/heating the fresh air being induced at ambient condition.

FAHU(Fresh Air Handling Units): As the name suggests, these units are associated with fresh air.

According to the facilities, the amount of fresh air required is determined, In hospitals(Operation Theater) the amount of fresh air required is maximum. In hot weather areas the surrounding air temperature is too high something in the range of 40-48 degree Celsius, So it requires more effort to condition the hot air. 

Recovery wheel in FAHU utilizes the cold return air coming from the conditioned space to cool or lower down the temperature of incoming fresh air. Recovery wheel transfer heat from fresh air to return air in order to lower down the temperature of fresh air. This process increases the efficiency of the system.

this is  like heat exchanger , it cooled the fresh air by the exhaust cool air from fahu

FAHU Recovery wheel using to cool fresh air  from out side high temperature to lower temperature using cold rejected exhaust air from inside building to outside  so can utilize the cold air and finally reach to power conservation . 

by an other way can say its uses to reduce FAHU (DELTA  T) THEN cooling capacity of FAHU.

The exhaust air drawn by the FAHU from toilets and kitchens enters the heat recovery component of FAHU and then discharged to atmosphere.

This creates a negative pressure in toilets and kitchens, thus the FAHU sucks cool air from conditioned space.

The cool exhaust air's heat energy before being discharged to atmosphere is saved by the heat recovery component of FAHU. The devices are of various types that are heat recovery wheel, heat recovery plate, and heat pipe. The function of this recovery devices is to absorb heat energy from exiting exhaust air (low temp)and transfer it to the incoming fresh air (high temp)of FAHU.

Thus saves some energy.

The rating parameters of all the components of FAHU shall be calculated by cooling load design

FAHU is Called Heat recovery unit its specially used for the place which need 100% fresh air and its functioning as heat transfer unit that extract cooling load from exhaust air and supply to inlet air. heat recover wheel is used for exchanging heat from inlet air to exhaust air . 2/3 of return air will not mixed with fresh air

We are using fahu recovery wheel to cool and dehumidify the fresh air in order to reduce the required cooling capacity and improve the indoor air quality..

Recovery wheel is used to conserve energy. Since exhaust air from toilets are near 24-25 Deg for example and fresh air is 38-40 Deg.

due to recovery wheel the air temperature of fresh fall down to 32 and exhaust air to 31 so FAHU has to do less cooling to fresh air at lower temperature.

Please note that fresh air is not mixed with exhaust air in FAHU.