Trane SFHL60 Programming Question

[emlev4512]

I've got 4 brand new boxcars, 2 of which have MWU capabilities (natural gas/ low heat 2 stage). Installers/foreman informed me that when MWU is enabled, SF VFD is commanded to 100%. Unit is controlled via BAS, but I've got pneumatics in the building, so my duct static shoots through the roof and trips the unit. Contractor is trying to sell us on re-vamping VAV's so that they can all be controlled via P/E switches....the only reference in the IOM to running the VFD at 100% is during the start up procedure. My question: why would the unit need to run the supply fan 100% regardless of how many stages of heat are being called for? I understand that a lack of airflow is detrimental to heat exchangers, but if a MGV is in place why couldn't I also modulate airflow?

[beenthere]

Moved to AOP Commercial forum.