Retrofitting extracting cooker hood

scottishblondie

Our house is currently lacking an extracting cooker hood, something which I miss greatly as the cooking smells tend to permeate the entire open plan living area. The ceiling is false, as the previous owners had all the ceilings dropped with insulation added above, so although it would be a messy job I imagine there is space to fit ducting. We would investigate this before going ahead with anything.

It would require a run of about 6m of ducting including a 90° bend. There is no way around this, as the cooker is on an internal wall and the only external wall opposite has a large flat roofed bay window - we have to go along first to come in line with an area of wall we could fit a vent in. I'm worried that this length of run will impact the performance of the hood and make the whole endeavour pointless, as one website said no more than 5m of duct and reduce that by 1.2m for each bend.

Can anyone offer advice on this? Also, what kind of trade would we need to fit the ducting? Usually my Dad would do it, but I have a lot of other jobs for him so I may need to consider a professional for this one!

Zuzel

First things first; 6 metres is quite a run for extraction with a diy-shed-type extractor.
There are box profiles for venting which almost undoubtedly would do the job easily, but you'd need a pretty powerful extractor to cope effectively with such a long run; the "el-cheapo" stack-'em-high-sell-em-cheap offerings won't cut it.
So look at the extraction rate of suitable fans as a starting point.
As for what trades - there's no problem DIY if you have a reasonable knowledge-base & it'll save quite a few quid too.
I'm wondering if the 90 bend would be above the extractor after entering the void ........ or will that make two?

bertiewhite

I recently fitted a cooker hood in our kitchen and went for a ductless one with carbon filters instead as there was no practical way to fit ducting.

jk0

I wonder if you could reduce the duct length by putting the ducting higher, between upstairs joists? Then would you be able to get the outlet above the bay roof?



Investigate which way the first floor joists run. This will have to be a job you do yourself though, as a tradesman will either bodge it or not want to do it at all.

neilmcl

As mentioned, you don't necessarily have to extract externally, most decent cooker hoods will allow for ductless extraction in conjunction with a carbon filter to remove odours.

Zuzel

Yes, a "decent" recirculating hood could do the job - but to do it effectively means spending good money on quality makes the likes of NEF or similar.

scottishblondie

Thank you for the suggestions.

There is no space between the top of the windows and the roof of the bay to fit a vent, so unfortunately the only option is to route it to the wall beside the bay.

I had completely forgotten the bend that would be required above the extractor itself, so I guess that makes 2 bends. The main run of the ducting would be in an L shape.

I'm not adverse to buying a high quality extractor I'd rather spend the money and be happy with the result. The one the previous owners fitted is definitely a cheap model, and it has no charcoal filter. I might consider upgrading to a better model that can be fitted as extracting or recirculating as an alternative to the ducting right now. Then if it performs inadequately in recirculating mode, consider fitting ducting then.