Convert Recirculating Chimney Hood - to an external extractor

[dishman]

Can anyone think of a way to turn a chimney style extractor, that is designed to extract from directly above or behind. To one which extracts from the side.

It is very similar to this image, so you should get the jist.

There is no side access to the metal chimney conduit/ducting.

It is currently a re-circulating unit (which I dislike). The outside wall is to the side and it already has a extraction hole drilled in. I am trying to work out a neat way to redirect the extraction out the side, but look neat and professional.

At the moment I can only think of cutting a circular hole in the side of the chimney conduit, attaching a circular bracket and then attaching either metal flexible hose. Maybe covering up with metal conduit (which seems hard to find) will make it look neater than visible ducting. The only downside is there will be conduit bridging the gap between the chimney ducting and the top of the cupboard.

Any other solutions or kit to do this that I am not aware of?

Many thanks in advance.

 

[nebjamin]

I had the same issue when we moved into our place. I used rigid pipe (less noisy than flexible metal tube) to run from the extractor outlet to the wall. I cut a hole in the side of the chimney to run the pipe. Obviously I then had a stinking great pipe across the top of the wall so I had a plasterer box it in flush to the top of the chimney. Once it was painted white it wasn't as obvious as my wife was worried it would be.

To make it less obvious you could carry the boxing in on the other side of the chimney. Just for symmetry like.

 

[dishman]

Looks like I am pretty much on the right track then.

I may go with an open "industrial look". Some of the spiral metal ducting looks decent enough to leave in plain sight.

Unless anyone else has any ideas. I am surprised there are no right angle metal ducting pieces for those who do not have an exterior wall above or behind.

 

[nebjamin]

One thing to note is that there is probably a spigot on the motor inside the hood (lift off the chimney) where you should connect the pipe. I wouldn't recommend just connecting to the top of the chimney as you'll get a lot of air leakage out the back and sides. I think this explains why there isn't rectangular ducting (because it's not meant to be done this way)

You'll probably find that if you lift off the chimney there is a location to connect a 4" or 5" pipe to get a proper seal. If there isn't there is usually a part you can purchase from the manufacturer. Something like this: http://static.premiersite.co.uk/15919/img/15919_5181428.jpg

 

[dishman]

Yes, i did not really mention, the chimney ducting is just a fascia, I am aware of that.
I meant I could not find any 90 fascia turns.

As you say there is the actual ducting inside with a 5"+ diameter hole above the motor to fit in a flexible ducting. I plan to put a 90 degree bend of mental spiral ducting into this. Then cut a hole in the chimney facia. I need to find some form of double sided bracket to support he ducting through the circular hole i cut. Then a run of circular spiral ducting out through the vent hole.

 

[dishman]

Spigot plate!

Ever had that thing, where you know what item you need to do/fix something but you do not know the name of the item you need or if it even exists.

Turns out, it does and it is called a spigot plate!

I plan to cut a hole on the metal ducting fascia, attach this internally so the round bit comes through the hole. That should allow the duct to fit on externally. I then connect the 90 degree turn to this on the inside using the correct connector m/f or f/m!

 

[Bubbles100]

I am currently having the same issue, my cooker hood is a recirculating one (only recently installed), having found out how useless it is, I now want to convert it to a ducting one instead. It was installed by an engineer, having paid so much already, I am hoping to convert it to a ducting hood by myself. I am not sure how to start, do I remove the top device where the air is currently being pushed out and just stick a flexible duct and lead it to the wall where the hole is?

This is the model of the hood http://www.bosch-home.co.uk/product...ods/wall-mounted-cooker-hoods/DWW077A50B.html

Any advice is appreciated.

Thanks in advance.

 

[dishman]

Hello,

I'm afraid it is normally a case of a diy bodge. Unless you can search for the item on the Bosch spares website in which a replacement chimney can be bought with a side exit for ducting. Bosch are a bigger company so there is a chance it is in their catalogue.

Maybe even call their spares line as it may not be easy to find (if it exists).

---

If a DIY job ends up being the only way. There are usually two screws at the top of the chimney where it meets the ceiling. Unscrew them, and the chimney should just pop out with a bit of jiggling. Maybe look for installation manual on the Bosch website as that will tell you how to put it in, then just reverse the steps.

There maybe some catches on the inside, so remove the grease filters and have a look under the hood.

After that, it is a case of cutting a circular hole in the chimney. Then getting some lengths of ducting to go up, 90 degree curved bend, through the hole you cut in the hood, then a length to the exterior wall.

Try to avoid flexi ducting as that just reduces flow a lot.

I'm planning to use the industrial looking 100mm diameter metal spiral ducting. No point trying to hide it for me. If you are boxing it in, plastic ducting would do fine too.