Hi

I was planning to build my own kitchen extractor rangehood.

I was originally looking at a schweigen UM11709SP undermount 90mm rangehood with 1600 m3 / h rooftop motor, cost $1700.

But I don't like that it has mesh filters instead of baffle filters (Baffle filters are quieter and easier to clean and seem better), also I'm not keen on a roof mounted motor solution because my roof is dual layer (Metal roof and then descrametic tiles) so would be a difficult install.

I'm investigating the possibility of getting a fabricated dumb rangehood, DIY ducting (either 200 or 250mm), an inline mixed flow fan (mounted to joists in the attic) and exiting the ducting via the a couple of vents on the eaves of the house next to the laundry.  I will probably speed control the fan via either and arduino, or wire it up to the rangehood directly (depends on which rangehood I use).

I assume the static pressure of the system would be approx 200 Pa if I use a couple of elbow joins to silence the fan noise and a baffle vent.

I was wondering if anyone has any experience in in-line fans, these are the fans I have been looking at:
btw - hydro-ponic places sell the same fans as the commercial ventilation suppliers a lot cheaper.

The vantech commercial fan shop recommended the Blauberg 200 mm, however I think the guy seemed a bit unhelpful and I think it wasn't really interested in giving me suggestions or advice.

Blauberg Turbo 200 mm fan - $335
Specs

Speed @ 200 Pa = 350 cm3/h (min) 575 cm3/h (max)
Sound pressure (3m) = 45 db -> 52 db
LWa to inlet = 75 db

Twin Turbo 200 in parallel (if not powerful enough)
- Speed @ 200 Pa = 750 cm3/h (min) to 1300 cm3/h (max)
Sounds pressure (3m) = 51 to 57 db

Can Fan Iso max 200 mm fan - $550
retail link / manufacturer link / Specs
Speed @ 200 Pa = 650 cm3/h
LWa to inlet = 59 to 62 dB
I am slightly worried the silencer may get full of grease?

Vortice 2speed Lino200 200 mm fan

Speed @ 200 Pa = 250 cm3/h to 680 cm3/h
Sound pressure (3m) = 46.2 to 52.5 dB

Or something like this - ikon ik16 - $500
Noise - 42 dB to 67 dB (but at what distance)
Speed - up to 1400 m3/h (but at what pressure, the other models seem to put out about 1000m3/h at 0 pressure)
I think this one is made in Turkey  and designed in denmark - so probably not as good quality and the specs seem a bit dubious for the price.