I have a conflict between NFPA and mechanical code that I need to resolve. Mechanical code (606 I think) requires duct smoke detector be installed upstream of any duct filter, and Mechanical Plan Reviewer is requiring compliance. But we have a client wanting to use a return grille with an integral filter, and that leaves no space for a sampling tube. NFPA 18.104.22.168.3 says manufacturer published installation should be followed. I have installation instructions (from System Sensor) that say detector should be installed downstream of filter since filters collect paper, dust, lint, etc., all of which are flammable. How does one resolve a conflict between NFPA and other codes?