A recirculating unit, like the Valent VR, conditions a mix of outdoor and return air and handles both ventilation and space heating/cooling in one package. It's the right fit when a single unit needs to do both jobs, especially in spaces that require more outdoor air than a traditional packaged rooftop unit can handle.
A DOAS unit, like the Valent VX, conditions 100% outdoor air to meet code-required ventilation and control humidity, while separate terminal equipment such as VAV, VRF, water-source heat pumps, fan coils, PTACs, etc. maintain space temperature. The Valent VX is the right fit when indoor air quality and humidity control are the priority, such as labs, healthcare, schools, and any building where other zone equipment handles space temperature but not ventilation.