Flexible duct for kitchen ducting

Yellow_Fern

Hi,

Is flexible ducting for running in wall considered kosher? Seems poor for preventing cavity wall voids but I wonder is it allowed. Thanks

Doolittle51

Allowed by who?

Rigid ducting is much better if you want to achieve a proper seal around the wall opening.

Yellow_Fern

https://www.boards.ie/discussion/comment/122333864#Comment_122333864

By the building regulations. Thanks. This flexible stuff seems to tear so easily and it is brand new. I will try to replace with rigid.

Doolittle51

You can buy short lengths of the rigid stuff in screwfix, along with any couplers, bends etc that might be needed.

The ope isn't very neat, but you should be able to get a round piece of rigid duct installed. Fill any large gaps with expanding foam, as deep as you can manage. Make good inside with plaster, outside with sand and cement and fit a new external grill.

Tefral

https://www.boards.ie/discussion/2058358142/flexible-duct-for-kitchen-ducting

This actually isnt installed as per section 1.2.4.4 of Part F of the TGD.

To be honest this is piss poor. I have never in my life actually seen that installation in all the jobs ive been on.

as per Diagram 5, a pipe is to extend from the front of the back of the cavity sealed in one piece.

Yellow_Fern

https://www.boards.ie/discussion/comment/122334914#Comment_122334914

That is very good to know. I dont know the regs but I can tell it is poor from an airtightness point of view because nothing sealing off the massive cavity wall void draught

Tefral

https://www.boards.ie/discussion/comment/122336800#Comment_122336800

Yeah no problem.

TJ in Munster HRV might get you some duct. Normally its a 4inch core bit which will make getting a 110mm wavin pipe offcut difficult to get through. I used 100mm duct and airtight foam (the blue stuff) to seal up and then put my vents on.

Kincora2017

Hi-jacking this thread a little bit, but just wondering if it’s acceptable to run an extractor fan duct through an existing chimney flu?

Yellow_Fern

https://www.boards.ie/discussion/comment/122345512#Comment_122345512

Did you find an answer? Would be interesting to know. you'd want to know the pressure drop. Ideally use rigid duct

Kincora2017

https://www.boards.ie/discussion/comment/122446609#Comment_122446609

I didn’t, but didnt really pursue it as we rejigged the layout. I’d be interested to know as well though