If the unit has a real, standard PVC connections (I can buy unions, if need be), does it matter that the mfg says "only for AG". or is that simply a means to say "if you're rich enough to own an IG, you pay 2x the price"?
Given that the units are installed immediately before the return goes underground. I don't see pressure being an issue.
Real concern, or just a way of improving profit margin?