We have experienced a problem with one of our York AHU (roof top unit) units sitting on the top of one of our office buildings. We experiences some sand like debries (corrosion product) coming to our office rooms from AHU units. It is relatively new unit.
We have no idea what is this. We performed all kinds of tests and we confirmed that it is not sand, but some corrosion debries.
We are planning to install a filter on the duct in between the condesor unit and AHU for the time being. Does any one have any idea about what is this? How to solve this problem? What kind of filter we have to go for? Where can we get those filters?