Make up air for high CFMrangehood(補充說明)

Make up air 對於風量高於400 CFM 的抽油煙機在2009IRC(2009國際民居規範）中規定如下：

M1503.4 Makeup air required. Exhaust hood systems capa- ble of exhausting in excess of 400 cubic feet per minute (0.19 m3/s) shall be provided with makeup air at a rate approximately equal to the exhaust air rate. Such makeup air systems shall be equipped with a means of closure and shall be automatically controlled to start and operate simultaneously with the exhaust system. 

這裏沒有要求不如空氣必須預先加熱或製冷。

這裏需要理解的問題是，大抽風量造成的室內空氣負壓可能有什麽危害。通常並不是擔心缺氧，而是擔心負壓導致空氣從煙囪倒流。極端的例子是，曾經有報道表明，大風量抽油煙機可能造成煙囪倒灌，甚至於，讓壁爐中的火焰衝出壁爐，朝向室內，有嚴重的火災危險。