I need help to answer a duct sizing, barometric damper question for a combined passive make-up air and exhaust type ACH system? (I've talked to the two HVAC shops in town and neither can help).
The data I need is what size of hard duct (and shape?) to feed continuous 50-60cfm bath fan (ACH) and provide make-up air for 250-300cfm rangehood, dryer, bath fan on full speed (110cfm)? I've got a number of ways I can duct this system. They range from 10' with 90 degree turn at intake/outlet(low/high), to 37' with 4-90 elbows (inlet/outlet plus two). I may temper the incoming air with a loop off of the radiant floor boiler.
Would you mention some barometric damper outfits with high quality/function products?
Some other data:
Propane cook top as only open combustion (elec. oven, boiler -radiant slab- with outside air intake and DHW loop).
Two people, two bedrooms
7500 HDD, east foot of Rockies, dry year round, no AC necessary.
Tight house (guessed at .25 ACH), 1725 sq.ft., 35% SSF (passive solar).
Only potential for intake is on predominently leeward side.