Kitchen ductwork

[bsr]

Hello

I will be fitting a kitchen with an extractor hood that has a 2.5m run to the nearest external wall. The hood (Neff D5655X0GB) has a 150mm diameter outlet but I only have 130mm between the top of the units and the ceiling! What do you suggest to maximise air flow?

Option 1: Reduce to 125mm circular and core through the wall as usual (not recommended by Neff)

Option 2a: Use an angled adaptor to 220x90mm, run that along the top of the cabinets and use a double airbrick adaptor through the wall

Option 2b: Use an angled adaptor to 220x90mm, run that along the top of the cabinets, adaptor to 125mm round to go through the wall

I prefer option 2a (rectangular) but how do you then go through the wall neatly? I don't know if my internal height will line up with an external brick so I risk breaking up several bricks and it looking crap.

Also, do you core for extractor and waste before or after fitting units? For the sink it makes sense to me to dry fit the unit and sink first and then core when I have everything in place. What about the extractor? I have a full-height larder unit with non-adjustable legs so everything will have to align to it.

Thanks


bsr

 

[Dereekoo]

Option 2a) Offer up outlet duct to internal wall, locate centre, drill through to outer wall. Decide which bricks need to be removed/cut/replaced/made good and if things do not line up exactly use giant air cowl from toolstation Product code: 50375 to finish external surface

 

[^woody^]

That rectangle duct has a greater cross sectional area so would be preferable.

It would be better to have a cowl or shutter to prevent back draughts and wind noise rather than just an air brick. Something that does not reduce the duct area too much.

 

[bsr]

Thanks both. That Toolstation product is useful.

When would you do this? Before the units arrive? And the same for the core for the sink drain? Part of me thinks it's better to offer up the units first to check levels.

 

[Dereekoo]

My preference would be when units have been offered up /are in position as far as possible, just to make sure you "get it right 1st time"

 

[^woody^]

It depends how accurate your marking out is. If you can trust your measurements, then drilling before installing units is easier.

 

[bsr]

This is what I did in the end, as recommended by the kitchen seller. Convert to 220x90 flat along the top of the units, then convert back to 150mm round in the cavity.

The rectangle to round adaptor was offset so the round part went below the top of the unit. This meant I could core through the wall. The disadvantage is that the adaptor had to be partially in the cavity and wouldn't fit into a 152mm hole so I had to try and find somewhere with a larger core bit (hard to find). In the end, one place rented me a 175mm.

 

[bsr]

Not my proudest DIY moment mind. Looks *** and I don't want the fascia rotting. Can you suggest how I should tidy this up?
Possibly a piece of alu plate to cover the bodge, and fill it with foam?

 

[^woody^]

This is the best I can come up with.

 

[Leofric]

Never seen that before , cutting through a fascia to install an extract duct Afraid I wouldn't know what to suggest to ' tidy ' that up.

 

[kingandy2nd]

...and fill it with foam?

Judging by the last effort I don't think you should ever be allowed to use expanding foam again

Could you get another piece of fascia the same size as the bit you've removed, and then cut the pipe shape out of the bottom of it with a jigsaw and then install with some fascia clips so it at least looks like you didn't just cut a whole massive bit out of the fascia?

Could you also remove that end plate and put something a little less unsightly...maybe something to make it look like a boiler flue instead?

 

[Ian H]

What about another angled square to round on the outside to point it down?

Would the fascia cover it?

 

[^woody^]

You need to fit a hood cowl, and then make good the fascia around it. Probably run that vented trim up and around the top of the "recess" to make it look like it was supposed to be.

 

[bsr]

Cheers, I know I need to fit the cowl. I was wondering whether to replace the fascia or to put some sort of cover plate over. Sounds like I need to cut out and replace the fascia. I'll jigsaw a hole as Andy says.

Hopefully I can still get whatever wierd colour that is...