150mm hole - close to the edge

[Diggory]

It’s a combination of things - even with a modest 600mm wide extractor (that I’ve returned); internal floor height, low eaves, 650mm above hob, turning 90deg with elbow, joining elbow (male) to spigot (male) with shortest section ducting………
It all adds up and puts me two courses down from top of wall.

 

[noseall]

It’s a combination of things - even with a modest 600mm wide extractor (that I’ve returned); internal floor height, low eaves, 650mm above hob, turning 90deg with elbow, joining elbow (male) to spigot (male) with shortest section ducting………
It all adds up and puts me two courses down from top of wall.

There aren't any joist or beam bearings, directly above the proposed duct are there?

 

[Murdochcat]

750mm if a gas hob

 

[Diggory]

Induction hob.
And no rafters / structural woodwork directly o’head.
So I could poke an (insulated?) chimney up/out through roof.

 

[noseall]

Induction hob.
And no rafters / structural woodwork directly o’head.
So I could poke an (insulated?) chimney up/out through roof.

We often duct through the roof (100mm). Not sure of the availability of 150mm ducting and waterproofing though?

 

[Ivor Windybottom]

Go out of the roof, it's much less destructive and works much better as the outlet is higher and you won't end up with all that warm damp air sitting under your soffit and possibly getting into the loft, especially if it's a vented soffit.

You should have a condensate trap as close as possible to the top of the ceiling. No need to insulate beyond that. I managed to sneak the drain pipe from my condensate trap through the top of the fascia and into the gutter. Totally invisible from below, and no drips.

100mm is adequate with a decent extractor and rigid ducting. I fitted 150mm on our last house, it was massive overkill.

You will need to ensure there's an inlet vent somewhere, I didn't and found it pulled air down the living room chimney at the other end of the house.

 

[Diggory]

…………..‘especially if it's a vented soffit’
Ummmmmmm - that’s an interesting point; it is vented / dry vented ridge.
There is no loft space - It’s a vaulted ceiling.
Just depth of rafters and (even more) Celotex.

Why did you find your 150mm an overkill ?

Thanks replies D

 

[foxhole]

You should not be any where near the top of the wall for kitchen extract. Mine is 4 rows down ( I inherited it that height) but could be 2 rows lower and still fine.

 

[Diggory]

You should not be any where near the top of the wall for kitchen extract. Mine is 4 rows down ( I inherited it that height) but could be 2 rows lower and still fine.

Thx reply - my original post explains why. I’d need to ignore manufacturers min height of 650mm to go lower.
—————————
Having read various and helpful replies - I think I have only two options

1.)Find an extractor with rear / horizontal exit so I don’t waste 200mm turning it with an elbow.

2.)Go out through roof

hedging my bets - I’m looking for 1.) and have a chimney on order.

Thx D

 

[Ivor Windybottom]

…………..‘especially if it's a vented soffit’

Why did you find your 150mm an overkill ?

It almost pulled a vacuum in the house, would make the place freezing and pull air down the chimney. It's a commercial grade really.

Total overkill for a home, 100mm is sufficient, as long at it's not the useless bendy ducting it's fine.

 

[noseall]

It almost pulled a vacuum in the house, would make the place freezing and pull air down the chimney. It's a commercial grade really.

Total overkill for a home, 100mm is sufficient, as long at it's not the useless bendy ducting it's fine.

A lot of cooker extractors are 125mm and above.

 

[Ivor Windybottom]

I think ours has an adaptor that converts down to 100mm. Can't remember now. Area is the square of the radius, so 50% more diameter is actually 125% more capacity, i.e. more than double.

It won't be harmful, but could be ugly. Just wanted to point out that 100mm is probably adequate unless you're running a chip shop or curry house.