what are hvac dx systems
What It Is. A direct expansion air conditioning (DX) system uses a refrigerant vapour expansion/compression (RVEC) cycle to directly cool the supply air to an occupied space. DX systems (both packaged and split) directly cools the air supplied to the building because the evaporator is in direct contact with the supply air, Expansion refers to the treatment of the refrigerant (a valve reduces its pressure and temperature) prior to it entering the evaporator.