What is an Energy Recovery Wheel?
One of the best ways to make a DOAS unit function more efficiently is to add an Energy Recovery Wheel (ERW). In many cases local codes make it necessary for HVAC units to meet minimum standards for efficiency. An ERW also called an Enthalpy wheel works as part of a DOAS unit to remove moisture and deliver room neutral air to the heating and air conditioning unit. By using an ERW the U.S. Department of Energy determined that energy savings of 15% are achievable.
Why you need an ERW
Commercial buildings are full of indoor pollutants and volatile organic compounds. These pollutants including CO2 accumulate everyday with office variants such as people, furniture, carpeting and office machinery. It is imperative that this polluted indoor air is replaced regularly with clean fresh air. If the poor indoor air is allowed to remain it ultimately leads to negative health effects to the building’s occupants. Although standard HVAC units cool and heat the air and provide minimal ventilation, they do not provide the amount of fresh air recommended by ASHRAE 62.1-2016.
How an ERW works
Energy Recovery Wheels work year-round cooling down the warm Summer air and heating up the Winter air. In either case the ducted sensible and latent heat comes from the outside where it goes through the ERW. Conversely the leaving or exhaust air also goes through the ERW where the absorbed moisture is expelled from the building. As the wheel turns it removes moisture from the air and changes the air to a room neutral temperature. The wheel will spin slower during the Spring and Fall season where temperatures are not as extreme. This in turn helps the cooling or heating unit perform better and leads to increased energy savings.
Conclusion
With the ERW rotating, recovered heat is moved from two streams of air transferring energy from fresh air and exhaust air. Proper ventilation removes contaminants from inside air and reduces energy costs. A United CoolAir DOAS unit including an Energy Recovery Wheel is a wise choice when replacing an existing unit.