Cooker hood super long ducting vs recirculation

[Patrick_]

Hi,

I'm renovating my kitchen. A new cooker hood will be installed, which supports both extraction and recirculation.

The issue is, the kitchen is located a bit far from the external wall. If I were to run a duct pipe, the route will be: 1.5m (up to the ceiling) + 90 degree turn + 6.5m (horizontal, to the external wall). That's quite long.

The cooker hood has a maximum extraction rate at 650m3 / hr. However, the long ducting pipe will obviously affect extraction performance. I wonder, should I still run the ducting, or just use recirculation.

All suggestions are welcome! Thank you.

 

[JohnD]

a recirculating hood is nothing but an ornament.

get an extractor

or a fan on the wall if you want.

or put the cooker in a sensible place.

 

[^woody^]

If you are minded to use recirculation, just save your money and don't bother fitting a cooker hood.

 

[Patrick_]

ok... thank you for the advice. I will run the ducting pipe.
Considering the length of the pipe, should I add a remote motor somewhere, perhaps after the 90 degree turn, to boost the air flow a bit..?

 

[^woody^]

Long ducting should not be an issue for an extractor, especially as the extractors tend to have centrifugal fans which are quite efficient with duct runs

Use as wide a duct as possible and avoid bends (or sharp bends) if you can, but its not a major thing as many times it's unavoidable, but the performance is still good enough. Depending on what material you use, there can be come reverberation noise in long runs, but if the duct is secured that tends to deal with that.

You don't need any boost motor device

 

[Harry Bloomfield]

Also use if possible, a smooth bore duct, rather than a flexible one. A suitable size of rainwater fall pipe works well and is cheap.

 

[Swwils]

If you can have an inline motor this will help if you cannot put in a larger diameter duct.

The larger diameter duct is key to reducing the static pressure that will effect the performance of the extractor over this distance.