Kitchen Ventilation - Outside or recirculate

[Paul_Thomas]

As part of our new extension we are installing an island extractor fan in the enlarged kitchen.

Do we have to extract to outside to meet Building Regulations ventilation requirements or is a recirculating unit ok?

 

[securespark]

Which one will be most effective?

Why not install the most effective solution?

Why are you trying to cut corners?

 

[ELZ4742]

what if the recirculating unit is better but not to regs?

 

[Paul_Thomas]

Not trying to cut corners, however Builder has removed some of the outside bricks in preperation to removing wall and said it looks as if the joists run a 90 degrees to what I expected. Therefore wouldn't be able to run ducting in roof space to outside wall.

I am just examinining options ready.

 

[Belle427]

filters can be expensive too if its a hood

 

[dingbat]

Do we have to extract to outside to meet Building Regulations ventilation requirements or is a recirculating unit ok?

There is no specific requirement to vent to outside directly from your cooker hood. Part F simply has this to say, "There shall be adequate means of ventilation provided for people in the building." If you could achieve adequate ventilation by opening the kitchen window the regulations would be satisfied

But don't take my word for it:

http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADF_2006.pdf

 

[JohnD]

A recirculator does not ventilate. It does not take steam awy. It has little effect on cooking smells. It will trap some of the fat particles.

Since it does not create any suction it will not combat the tendency of cooking smells and steam to diffuse throughout the house.

At the very least fit a powerful extractor fan.

 

[dingbat]

I meant to add that I would always recommend a decent extract fan for a kitchen, whatever the regulation requirements.

 

[Paul_Thomas]

I've cut a small hole in the ceiling where it will have to be removed to install a RSJ. Joists run wrong way for me. They run towards the nearest outside wall which sounds ideal apart from the fact that I have a conservatory on that wall!

Easiest (But not really best) solution is to run pipe to this outside wall, then 90 degrees down and run along the corner of the ceiling for 400mm then out through the wall. Not ideal having two 90 degree angles but it will stop any condensation running towards the extractor. Total run is approx 2 - 2.5m. I would then box this pipe in.

The Extractor will be a 900mm Baumatic ISL5SS which has an extract rate of up to 500m/3 hr, way more than the 108m/3 hr required by Building Control.

 

[jj4091]

I've cut a small hole in the ceiling where it will have to be removed to install a RSJ. Joists run wrong way for me. They run towards the nearest outside wall which sounds ideal apart from the fact that I have a conservatory on that wall!

Easiest (But not really best) solution is to run pipe to this outside wall, then 90 degrees down and run along the corner of the ceiling for 400mm then out through the wall. Not ideal having two 90 degree angles but it will stop any condensation running towards the extractor. Total run is approx 2 - 2.5m. I would then box this pipe in.

The Extractor will be a 900mm Baumatic ISL5SS which has an extract rate of up to 500m/3 hr, way more than the 108m/3 hr required by Building Control.

if you use white plastic ducting it will do a nice neat job with no need to box -in

 

[bernardgreen]

Have you considered a dummy "oak beam" across the ceiling. Hollow this conceals the ducting and cabling to and from the hood.

 

[dingbat]

How very 1970s!

 

[stem]

Considering all of the pro's & cons may help you, not just how easy or not it is to install.

Recirculating is easier to install as there is no need to make a hole in your wall and/or run ductwork. However, you will have to be disciplined to change a filter regularly depending on how often and what you cook. The air laden with cooking smells passes through the filter, which usually made from activated charcoal and the smells are removed (in theory, as the filters are not 100% efficient) the filters are easy to replace, but not usually cheap and their efficiency tails off as they are used. I've known people switch on the hood and cooking smells enter the room before the cooking actually starts! It also means you will not be removing the air from the room, so you will not be loosing your heated air. Good in winter, bad in summer. This is usually the DIY method of installation because its easier.

Outside venting gets rid of the air and heat to outside giving far better ventilation and you will not need the activated charcoal filter. This is usually seen as the "professional" method of installation unless it's impractical to run ducting. Long lengths of ductwork (especially the rectangular crossectional type designed to lie flat on the top of cupboards) will also reduce the effectiveness of the fan.

Both types of hood need a grease filter of some sort to stop grease clogging up the fan. Some need to be replaced others are washable.

I personally would go for outside venting if at all possible.

Hope this helps