Cooker Hood Help!

[ScubaCollie]

Hi All, we purchased a house 2 years ago and have gone to replace the existing cooker hood and having issues with meeting the Building Regulations and Manufacturers recommendations.

Link to the hood we've purchased at bottom of post.

Problem.
We have a gas hob and therefore the minimum hood height must be 650mm from top of hob.

We then need 780mm minimum from bottom of hood/fan to top of hole in wall (as per manufacturers instructions) but we only have 710mm available.....and we can't block off and drill another hole any higher due to a structural joist in the way.

What would you guys do?

It's unfortunately not an option to return the hood....

Link to hood below.

https://ao.com/product/dwk87em60b-b...K3mUn3l-_1nZ_MmndT1409ZT0BUIRSOxoCmMsQAvD_BwE

 

[conny]

Not an expert in these things but 60mm = 2-3/8" in old money. I really can't see this difference being absolutely critical to it's safe functioning or there would be be highlighted warnings in clear view before purchasing. I would make sure it is the 650mm from the gas hob and then just take it as high as possible at the top.

 

[Mr diy a lot.]

Crack on - this is a non problem. Your measurements you are having to work with are meeting the spirit of the regs/guidance. You are talking about a ‘mere’ 7cm away from meeting the recommended installation situation. Either split the difference so your hood sits at 615mm above hob and you run you hood to hole at 755mm or keep the hood at 650mm and just take 7cm of your hood hole position. Both are fine. It’s your own house - a retro fit cooker good install does not require building regs sign off - so no one is going to be hanging you out to dry over a few cms!

 

[JohnD]

I see the white plastic spigot coming out of the casing in the rear view. Will you be putting an elbow on this to go through the wall duct?

Something like

post some photos please. There may be a shorter fitting you can use.

Otherwise, could you drill a new hole higher up? I prefer to see an extractor that is high enough that you can't bang your head on it.

 

[tell80]

FWIW:
Gas needs 750mm above the hob.
Elec. needs 650mm above the plate.

 

[JohnD]

FWIW:
Gas needs 750mm above the hob.
Elec. needs 650mm above the plate.

Or more.

 

[ScubaCollie]

Hi Guys it states 650 in the Manufacturers Instructions please see below?

 

[ScubaCollie]

I see the white plastic spigot coming out of the casing in the rear view. Will you be putting an elbow on this to go through the wall duct?

Something like

View attachment 266161

post some photos please. There may be a shorter fitting you can use.

Otherwise, could you drill a new hole higher up? I prefer to see an extractor that is high enough that you can't bang your head on it.

Hi mate. Please see below photo, but yes I will be fitting an elbow, going to try and get a 110mm soil pipe elbow fitting.

The other problem I have is the existing ducting through the wall was that white flexi stuff that you often see on tumble dryers and it had caught on the wall when they installed it and was all torn within the cavity and it's a timber framed construction!

The problem I have is the hole through the wall is only 120mm Max Dia (manufacturer requires 150 recommended/120 minimum) and it's not possible to get a 120 duct therefore, therefore I purchased some upvc pipe, cut it in half, folded it over to see if I can get it through, but because the hole has a huge timber joist right on the side of the hole, you can only get a max 115mm through it.

Ive therefore purchased some 110mm soil pipe and have cut that and put through the wall as you can see in the below photo, the other side goes into the garage and vents above the extended ceiling!! This is because that wall was originally an external wall, but they then built an extension over that wall for the garage and the ceiling for the garage is below the fan outlet!

Also the wall plate hole is too big for the 110mm soil pipe I purchased, I therefore got some Fire Retardent sealant and fixed it in and sealed it all around with that.

We were wondering why we could smell cooking upstairs in our bedroom,

 

[JohnD]

Hi Guys it states 650 in the Manufacturers Instructions please see below?

that is the minimum figure.

It actually says ≥650mm

where the symbol ≥ means "more than or equal"

 

[JohnD]

I have seen some "flat" connectors that are not the same as an elbow

this one does not do quite what you want but it might be possible to assemble something. The rectangular duct also needs less height in the wall.



various other fittings

on mine (shown in earlier photo) I reduced the height of the elbow by using a different kind of reducer, and minimising the riser

there are a few cooker hoods that have an exhaust port in the back, but modern ones mostly exhaust through the top

or you can run the duct along the wall to a more convenient place.