So my HVAC plans have left a few lingering questions. Hopefully I can get some opinions on some of these:
1) I plan on an inline centrifugal fan (180-200 CFM with variable speed control) drawing from the 2 return ducts (dampers to select high/low register). The supply ducts have the option of drawing from the air handler or from an adjacent room via 2 powered dampers. In situations where the air handler is kicking out heat for the house but the room needs cooling then the supply will come from the adjacent room rather than the 90 degree heat from the furnace.
Should my exhaust fan dump directly into the main HVAC return or rather into an adjacent room? If a 200 CFM fan is blowing into the main HVAC return which already has lower pressure because main fan is ON then does it effectively become more than 200 CFM overall (logarithmic math maybe)?
2) At about 17', will my PJ be too far from an AT CIH screen (120-130") to provide enough brightness (will be zooming)? I know it depends on PJ but just wondering if I'm getting into a higher class of PJ just to satisfy mounting in rear soffit. If that's the case, I may consider mounting PJ from ceiling and adjusting return ducts for venting.
3) Can I leave the return opening next to the PJ wide open or do I need a register. Is the register just for aesthetics reasons? Any suggestions on diffusers for a supply run that is rectangular and 51"sq?
4) At 200 CFM the room would be getting about 6 exchanges per hour. Sound about right for a well insulated, windowless, basement, equipmentless, six peopleless...type of room-ish
This would also give me just over 250 FPM at the diffusers.