When designing 100% OSA systems you have to account for airborne contaminants, extreme ambient temperatures, extreme relative humidity, proper building pressurization, corrosive air, coil freezing, part load performance, and sophisticated control sequences.
Conventional packaged rooftop units have trouble dealing with the extras that come with 100% OSA. Don't be fooled into thinking that the everyday sedan is a high performance race car. Their rapid mass volume production will leave you with flimsy construction, limited options, and control issues due to application inexperience.
Go with the experts who know 100% OSA. Use Valent Air rooftop packages who are driven soley by 100% OSA market demands. They provide superior construction, product flexibility, and factory testing because they know that you want the job done right the first time around. Now that is a breath of fresh air.