Convert Extractor Hood to be external

jonny2510

I'm looking to convert the extractor hood in our kitchen to pump the air it extracts outside, rather than just recirculating it round the kitchen.

The hood was already fitted when we bought the house, and there is no sign of a make or model (or any other parts).

I took the chimney part off this morning to take a look, and I believe I should be able to convert it to pump the air outside (we're having condensation problems!) rather than just recircuating it.

Is there a standard kit to allow this to be vented through the wall (which is an external one)?

Can anyone offer any advice?

Pictures are below:

- The hood

- The extactor switched off

- The extractor switched on

Mikeyorks

Presume there's an aluminium chimney sits on top of that?

Mine goes up the aluminium chimney and through the ceiling in rigid plastic pipe (easier to seal around rigid pipe with flexible filler) and into the loft (bungalow) - where it joins to flexible pipe across the loft and out the fascia.

If you have a room above - then you've really got to make the outlet behind the aluminium chimney (question above). As you can't take a plastic pipe [(rigid or flexible) out of the side of the chimney (to get it across the top of cupboards etc - to somewhere where it's easier to creat the outlet to outside)] - without it looking silly

All the bits you need here :-

http://www.screwfix.com/app/sfd/cat/cat.jsp;jsessionid=2TIBTUHDVILD2CSTHZPCFFA?cId=100139

- or on the TLC links I've posted on your bathroom extractor thread. You just put appropriate size flexible / rigid circular pipe over the spigot on top of your hood - seal it with duct / aluminium tape - then work out whether to get to the outside (there's a converter) using flexible or rigid pipe - flexible being easier.

If your builder friend has a core drill - use that to make the hole through. But drill a pilot through then do the work from the outside - as much less mess. Consider hiring a core drill for an hour if he hasn't got one? If the spigot on top of the hood isn't 4" (or 100mm) then it should be 5". You'll need the right size to go over the spigot (must go outside - not inside, or you'll foul the baffles that open) - then get a converter to reduce to 4" - as that's neater / easier to manage as it goes outside. Kitchen extractors are 'low pressure' - and 4" is more than adequate to vent the flow of air.

When all is in place - have a look at the inside of the hood and remove any carbon filters and throw them away. They're for 'recirculating' - and only retain unnecessary smells / impede the air flow when you've got it set up for 'extraction'.

It's the right way to go - as 'recirculating' kitchen extractors are pretty useless. They chuck grease all over the wall (even if you think your cooking is 'greasless' - incredible where it comes from) / do nothing for smells and steam. Worth the effort to get it outside!

jonny2510

Mikeyorks wrote:

Presume there's an aluminium chimney sits on top of that?

Yes, sorry, forgot to mention that.

Mine goes up the aluminium chimney and through the ceiling in rigid plastic pipe (easier to seal around rigid pipe with flexible filler) and into the loft (bungalow) - where it joins to flexible pipe across the loft and out the fascia.

If you have a room above - then you've really got to make the outlet behind the aluminium chimney (question above). As you can't take a plastic pipe [(rigid or flexible) out of the side of the chimney (to get it across the top of cupboards etc - to somewhere where it's easier to creat the outlet to outside)] - without it looking silly

The white gap (between the tiling) you can see in the pictures where the chimney goes is actually an external wall. Would this be ok to send the pipe to (i.e. directly up and straight into a right angle through the wall)?

All the bits you need here :-

http://www.screwfix.com/app/sfd/cat/cat.jsp;jsessionid=2TIBTUHDVILD2CSTHZPCFFA?cId=100139

- or on the TLC links I've posted on your bathroom extractor thread. You just put appropriate size flexible / rigid circular pipe over the spigot on top of your hood - seal it with duct / aluminium tape - then work out whether to get to the outside (there's a converter) using flexible or rigid pipe - flexible being easier.

If your builder friend has a core drill - use that to make the hole through. But drill a pilot through then do the work from the outside - as much less mess. Consider hiring a core drill for an hour if he hasn't got one? If the spigot on top of the hood isn't 4" (or 100mm) then it should be 5". You'll need the right size to go over the spigot (must go outside - not inside, or you'll foul the baffles that open) - then get a converter to reduce to 4" - as that's neater / easier to manage as it goes outside. Kitchen extractors are 'low pressure' - and 4" is more than adequate to vent the flow of air.

Just measured it, and it's actually 6" Diameter. Would this be suitable?
http://www.tlc-direct.co.uk/Products/BGDK6.html

with one of these to attach to the spigot (my new word for the day), and then some tape to finish it off?
http://www.tlc-direct.co.uk/Products/FD6CLIP.html

or would I be better using one of these (with the 5" kit), to increase the pressure slightly?
http://www.tlc-direct.co.uk/Products/FD65118.html

Additionally, you mention aluminium / duct tape. As I have neither, and will probably be placing an order from that site, is either one better than the other for this particular application?

When all is in place - have a look at the inside of the hood and remove any carbon filters and throw them away. They're for 'recirculating' - and only retain unnecessary smells / impede the air flow when you've got it set up for 'extraction'.

It's the right way to go - as 'recirculating' kitchen extractors are pretty useless. They chuck grease all over the wall (even if you think your cooking is 'greasless' - incredible where it comes from) / do nothing for smells and steam. Worth the effort to get it outside!

There are no carbon filters in place, but as you mentioned, the chimney bit is covered in grease.

Finally, is it as easy a job as drilling a 5/6" hole through the wall (with a core drill), feeding the tube (attached to the grill) through (from the outside) and attaching to the spigot?

Is it the type of thing an amateur (i.e. me) with a hired core drill could do to cut down the labour costs of the builder (and leave him to sort out the extractor fan)?

What would I seal it with from the outside?

Thanks for your detailed replies to both of my posts. They're trully appreciated. It's great to be able to get such detailed independant advice on these things (of which I have no idea about). It's something I really should have sorted long ago.

The reason I'm fitting them is that we live in a solid brick house, and damp (which we believe is caused by condensation) is a problem.

Am basically trying to prevent as much moisture as possible from getting into the house, (we've already converted to using a condensor dryer as oppose to drying clothes on the radiator)

Mikeyorks

jonny2510 wrote:

The white gap (between the tiling) you can see in the pictures where the chimney goes is actually an external wall. Would this be ok to send the pipe to (i.e. directly up and straight into a right angle through the wall)?

Yes - from what I can see it looks OK. If you've got a chimney in a downstairs kitchen - your options on external venting are limited, I'm afraid

Just measured it, and it's actually 6" Diameter. Would this be suitable? (1)
http://www.tlc-direct.co.uk/Products/BGDK6.html

with one of these to attach to the spigot (my new word for the day), and then some tape to finish it off? (2)
http://www.tlc-direct.co.uk/Products/FD6CLIP.html

or would I be better using one of these (with the 5" kit), to increase the pressure slightly? (3)
http://www.tlc-direct.co.uk/Products/FD65118.html

Hmm .... certainly didn't expect it to be 6". I think (3) - the 6" to 5" reducer will cause you a problem? As I suspect the shoulder, where it reduces, will foul the baffles! So - either use 6" throughout, or put a 6" piece of rigid pipe over the spigot for the first few inches - then put the reducer in place on top of that.

But personally - I'd now go for the 6" throughout. Start it off with one of these :
http://www.tlc-direct.co.uk/Products/FD61350.html
.... directly over the spigot. The (1) wall grille appears to have a section of flexible aluminium pipe attached ('expands to 13"?') - which should stretch back through the hole and couple over the rigid pipe. Then tape the flexible pipe to the rigid / tape the rigid to the hood top around the spigot - and that should be it? But you need to buy the length of rigid pipe that overfits the distance from the spigot to where you cut the hole - then cut the rigid pipe to length with a tenon saw or similar.

Additionally, you mention aluminium / duct tape. As I have neither, and will probably be placing an order from that site, is either one better than the other for this particular application?

Not really - but I tend to use the aluminium if I'm using that type of flexible pipe. And you'll find it potentially useful for the bathroom extractor?

Finally, is it as easy a job as drilling a 5/6" hole through the wall (with a core drill), feeding the tube (attached to the grill) through (from the outside) and attaching to the spigot?

Is it the type of thing an amateur (i.e. me) with a hired core drill could do to cut down the labour costs of the builder (and leave him to sort out the extractor fan)?

Without offence - it's easy if you're a competent amateur! Personally I'd get all the stuff - hire a drill if he hasn't got one - but let him put the hole in? You need a pilot from the inside and getting 6" holes in the wrong place isn't easy to disguise?

What would I seal it with from the outside?

Nothing - if you've got a neat hole. It's actually a bit tricky doing the final bit as you've got to offer the grille into the wall - get the flexible pipe through - and then put a couple of screws into the wall to hold the grille (the flaps open but still make for difficult access?) - whilst keeping everything in place. A 3 handed job - but means you can't seal round the pipe, but you don't need to. But I would put a bit of flexible filler (or the tape) - from the pipe to the wall, on the inside. Stops woodlice etc from the outside / cavity?

The reason I'm fitting them is that we live in a solid brick house, and damp (which we believe is caused by condensation) is a problem.

Am basically trying to prevent as much moisture as possible from getting into the house, (we've already converted to using a condensor dryer as oppose to drying clothes on the radiator)

Know the problem well. Up to 2 years ago I spent the previous 18 years in a 400 year old solid wall farmhouse. Rampant damp caused by condensation when we moved in and despaired of shifting it. But bathroom / kitchen extractors / care with steam and ventilation / and sympathetic decorating (silk vinyl paint is not for solid walls - something not known to the previous owners) - fixed the lot.

Trust it helps you.

jonny2510

wow!

Thanks again for the advice, and quick reply.

Will post back when I get the work done (could be a week or so yet), and will post any other queries in the meantime.

Thanks again, it truly has been helpful

Emmysmum_2

Good luck.....and there should have been a carbon filter in there the way it was installed originally!!!!!

Mikeyorks

jonny2510 wrote:

Thanks again, it truly has been helpful

You're welcome. Sounds like you're doing all the jobs I started on 18 months ago and have now, fortunately completed. But getting smells / steam out of the house is an underrated achievement - and well worth the effort in the long run. Although I wasn't too convinced at the last house - cutting through 2 feet of solid stone wall,for the bathroom vent, whilst perched on the roof - in the snow. But the frostbite has cleared.;)

Been travelling daily to my parent's for weeks to help out with problems - hence rare appearances on here and for next few weeks. But will try to stay abreast.

golddustmedia

Every possible variation of extractor fan ducting (including round to square and low profile adaptors) is available from Toolstation, I used them to route my kitchen hood to a wall outlet using the low rectangular ducts on the top of the kitchen cupboards!

http://www.toolstation.com/shop/Electrical/Ducting/d190/sd3083