Ducting length for a cooker hood extractor fan?

[HappyHippyDad]

Good evening all.

This job applies to a new, or rather replacement kitchen. Walls have been taken down, extensions added etc etc. It's a big job. The new kitchen is in the same area as the last one but has been made bigger.

The cooker hood fan has been installed with a carbon filter (as it was before, i.e existing). The customer has now changed there mind and wishes to have it vented out of the house.

This would involve a run of approx 6m and 2 x 90degree bends. Rigid ducting.

I'm a bit uncertain how to determine if this is acceptable. If it was just the customer asking then I may be inclined to just do it, as I'm sure it would still meet the 30L/s minimum requirement, even with such a horrible ducting run. I dont have the MI to hand but the cooker hood will do approx 100L/s vented directly out of the wall.

Part F even says you don't need extraction if the existing didn't have it, as long as its in no worse condition (3.31). Meaning the long ducting run will still be better than existing.

It's a little confusing. Any ideas/suggestions?

I have asked the builder to clearly ask the building inspector what he would be happy with.

PS.. I don't think the customer would be happy with a separate fan elsewhere, venting to the outside (even though that would be much easier).

Thanks.

 

[binky]

I suspect it will work fine, especially if using a smooth walled pipe. The airflow part of F is really aimed at new builds
, which are far more airtight than existing buildings. My own house was built in 1886, airflow is not an issue as there's ruddy draughts everywhere

 

[Murdoch]

It’ll be fine as long as you use rigid round ducting.

Part F applies to new builds AND extensions

 

[Richard-the-Ninth]

..........just saying Click me

 

[Chewbacca]

..........just saying Click me

Interesting, that's been kept surprisingly quiet.

 

[Murdoch]

Thankfully the retired are the lucky ones.

What is alarming is that many “builders” don’t understand the current version of part F

 

[kerching]

Part F is an effing joke NICEIC want £400 fora 2 day course……who would have thought they would be promoting an Only Fans revenue stream. BC won’t sign off a job unless it has the Part F sign off, flow rates, design, pressures etc