Best grille for extractor?

[reg091]

Don't know where to post this so will try here!

I have been looking into extraction rates for fitting a powerful through the wall extractor fan for a utility room.

Having looked at airflow rates and identified a "industrial" fan as the way to go it occured to me that the external grille might have an impact on the extraction rate.

Is one kind of grille better than another? I would think that the ones with gravity flaps will allow better airflow than (say) the fixed grid with a flyscreen behind it. But maybe I am just overthinking it!

 

[Burnerman]

Having had enough of the cheap plastic outlets, I now go for the stainless steel range of louvre terminals from Toolstation.....perhaps slightly noisier than the plastic types, at least they don’t stick open.
John

 

[foxhole]

Found flybscreen models act like a vacuum filter and block quickly with fluff and dust etc.Especially with high speed fan.

 

[reg091]

Thanks guys. Toolstation looks the way to go. My only issue is that the fan outlet is big (250mm) so that limits my choice it seems.

 

[foxhole]

https://m.ebay.co.uk/itm/Metal-Grav...b91effee9ab9&_mwBanner=1&_rdt=1&ul_noapp=true

 

[reg091]

Thanks foxhole. They are out of stock of the 250mm, I have mailed them for availability and will keep looking.