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Connect cooker hood to existing extractor fan?

Postby ADMD » Fri Jun 11, 2021 12:04 pm

I've got a small kitchen with an extractor fan that switches on with one of the lights. I'd like to install a cooker hood, and want to know if I can connect the vent to the vent behind the extractor fan. Ideally I'd keep the existing fan (if it could be repositioned) such that both of the fans (wall and hood) extracted when required, and passed the air out of the same outlet. Alternatively, it would be OK just for the wall-mounted fan to be ditched, and replaced with the cooker hood.

Do either of these options seem plausible, and what should I be aware of if doing this myself?

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Simply Build It

Postby ericmark » Sat Jun 12, 2021 4:00 am

As to if allowed to DIY depends on where you live, England yes, Wales no or at least not unless willing to pay more to council than a scheme member electrician would cost. Although I suspect very few follow the rules, unless rented.

As to two extractors into same duct, the problem is ensuring no back flow.

Kitchens can be a problem due to build up of grease or fat, and this can stop flaps closing, also there is the question with any extractor where will the air be replaced from?

Big problem is the open flue, don't want to draw in combustion gases into the house, we tend to block air vent bricks, either by accident with cavity wall insulation or intentional. We also try to stop drafts.

You can get heat recovery units where the air out goes through same hole as air in, the heat exchanger is built in to the pipe through the wall, but OK bathroom, but kitchen not so sure about grease build up?

Google 100mm In-line Extractor Fan Vent Back Draught Shutter With One Spring And Two Flaps and you will see non return valves, so can be done, but first work out how air gets into kitchen/house, do not want to draw in fumes from a gas fire etc.
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Postby ADMD » Tue Jun 15, 2021 1:35 pm

That's very helpful - thanks. (And to answer your first question, I'm in Edinburgh!)

Think I'll get a professional to come and take a look at it...

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