Ducting for Neff venting hob

Rodders53

Most of these will be fitted as recirculation devices - especially on Island installs.  So room airtight is not an issue.

But in any case Building Regs require trickle ventilators in such rooms' windows and doors, I believe? https://www.planningportal.co.uk/info/200135/approved_documents/68/part_f_-_ventilation

coffeehound

It would require an awful lot of trickle vents to give unrestricted flow for a powerful fan.  The area of 150 mm ⌀ ducting is about 177 sq cm, so you'd ideally want at least that gap open to the outside air

sittingonthefence

I was just wondering if you managed to get the non-branded ducting to work? I have this exact same problem at the moment for the same hob! Many thanks

Ballymoney

sittingonthefence said:

I was just wondering if you managed to get the non-branded ducting to work? I have this exact same problem at the moment for the same hob! Many thanks

Yes, it worked a treat. I bought the branded piece that connects to the hob (part Z861SB2 i think?) just to get a secure connection and then used basic 220 x 90 ducting from TLC Direct to take it to the external wall. Our builder just used duct tape to connect it to the Neff part. Saved a considerable amount of money and i've had no issues so far.

Doozergirl

coffeehound said:

Ballymoney said:

The ducting goes to an external wall and out of the property via an external wall grille.

Thing is, there needs to be a path for air to easily enter the building in order for the fan to remove a large volume at the hob.  In a modern draught-proofed home, the fan will struggle to work if there is no way for outdoor air to enter the kitchen, such as an open window

That's interesting.  I'll have to check if there's any difference on ours when the door is open!

coffeehound

Doozergirl said:
That's interesting.  I'll have to check if there's any difference on ours when the door is open!

I wondered what the situation is with MHRV -- does your system have an extract duct in the kitchen?  I guess you definitely don't want cooking grease getting into the system!

Doozergirl

coffeehound said:

Doozergirl said:
That's interesting.  I'll have to check if there's any difference on ours when the door is open!

I wondered what the situation is with MHRV -- does your system have an extract duct in the kitchen?  I guess you definitely don't want cooking grease getting into the system!

Yes it does.  Not directly over the hob but not far away.  

The downdraft extractor just recirculates to get rid of the grease.  I'm religious about using it for that reason, which reminds me that I need to buy a new filter! 

ComicGeek

coffeehound said:

Ballymoney said:

The ducting goes to an external wall and out of the property via an external wall grille.

Thing is, there needs to be a path for air to easily enter the building in order for the fan to remove a large volume at the hob.  In a modern draught-proofed home, the fan will struggle to work if there is no way for outdoor air to enter the kitchen, such as an open window

Not really, unless you have an ultra air tight house, have the smallest kitchen known to man, have internal doors closed without any undercuts, no trickle vents etc. There's plenty of indoor air than can be moved around and partially replaced before the house starts to depressurise. Most kitchen hobs will struggle to extract more than 30 litres/second - a 10mm undercut below a single closed internal door will provide about 20 l/s of this, an open internal door considerably more. The rest via natural infiltration, trickle vents etc. Ultra air tight houses will have MVHR systems to balance supply and extract rates, with recirculation hoods so that they don't have positive/negative pressure issues - even then, they will have pressure differences between rooms which are managed perfectly well with a 10mm undercut to internal doors.

I did look at some lab clean rooms recently where the supply rates meant that the doors were very difficult to open once closed, as it was highly positively pressurised and the doors opened into the room. But have never had that for any large commercial kitchen, let alone a residential kitchen.

sittingonthefence

Ballymoney said:

sittingonthefence said:

I was just wondering if you managed to get the non-branded ducting to work? I have this exact same problem at the moment for the same hob! Many thanks

Yes, it worked a treat. I bought the branded piece that connects to the hob (part Z861SB2 i think?) just to get a secure connection and then used basic 220 x 90 ducting from TLC Direct to take it to the external wall. Our builder just used duct tape to connect it to the Neff part. Saved a considerable amount of money and i've had no issues so far.

Amazing.  Thanks so much for the reply.

Sandtree

Ballymoney said:

sittingonthefence said:

I was just wondering if you managed to get the non-branded ducting to work? I have this exact same problem at the moment for the same hob! Many thanks

Yes, it worked a treat. I bought the branded piece that connects to the hob (part Z861SB2 i think?) just to get a secure connection and then used basic 220 x 90 ducting from TLC Direct to take it to the external wall. Our builder just used duct tape to connect it to the Neff part. Saved a considerable amount of money and i've had no issues so far.

How are you finding the hob itself @Ballymoney

I've recently lost my discount on Neff/Bosch/Siemens and about to lose my discount on Miele but with the discount I can pick up their version for about the same price that the Neff model is normally listed at. Lots of people however are recommending Bora as a quieter/better option and a few recommend Novy which I'd never heard of before but its the rising style of extraction rather than flush with the hob when running.

Been procrastinating for a while but dont want to end up getting one of the options at full price that I could get discounted now.