Extractor fan emptying into chimney stack

In our new kitchen plan we will have our cooker in the current unused chimney stack. I know we need a liner to stop build up of grease causing a fire hazard. However I finding it hard to find information online about which extractor will be suitable. All sites seem to selling fully integrated (into a cupboard), or with chimney hoods, but we don't need a hood as we are keeping the chimney breast as a feature. We want a powerful one as this will be a living area too.

Any advice on what we need or other points we may not have considered?

Many thanks Suzanne

Reply to
SC
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I'm thinking about the same thing.

How does a liner help prevent a build up of grease? Do you mean a liner for the whole flue or just for the opening where you will put the fan.

However I finding it hard to find information online about

I plan on using a hood

Reply to
Chris Harris

Yes the whole length. Apparently if there is a special liner off the brick walls you are less likely to get a chimney fire. The liner is non flammable and grease build-up in it is less like to cause a house fire. So our architect told us.

We would have to remove the chimney breast and put in a concrete head to support the fireplace above or remove it the full length of the house. We would then have to run a vent 16' to the nearest outside wall, so venting up the chimney makes a lot of sense. I would like to make a feature out of it like this kitchen from Arena:

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Reply to
SC

Your Architect is giving poor advice.

It is important to prevent the grease from reaching the fan and ducting in the first place.

Grease filters stop the fan getting clogged and thus premature wear, and prevent grease from getting to the flue in the first place. No liner is going to prevent built up grease catching fire.

Any set up you decide on, should have cleanable, grease pre-filters before the fan.

If non of the manufacturers have a specific model for your purpose, then a standard cooker extractor box could be adapted.

dg

Reply to
dg

I have to agree with DG, I don't see how a liner will prevent any build up of grease, not even a teflon coated one!. I plan on using a good quality filtered hood to prevent the grease getting into the chimney. I haven't chosen one yet so don't ask what one :-)

faced with just a hole where the old Rayburn flue entered about 2m above floor level so fitting a hood is not a problem for me.

It looks to me as if you could adapt one of those cooker hoods that fit into the wall units of an off the shelf fitted kitchen. Make sure that the fan and motor box will fit inside the chimney, make a custom filter box and shove the whole thing up inside.

Reply to
Chris Harris

I have a similar set up, with range in the chimney. The fireplace has been widened and heightened. However, the flue stops abrubtly with some floorboards in the room above.

I was planning just to block off the flue 30cm above the lintel with some multiboard. My partner is vegetarian, so there won't be much meat cooking going on.

Do you think I'll need an extractor as well? This would require about 3m of horizontal ducting above kitchen units and a centrifugal fan. Is it possible to get concealed centrifugal fans complete with grease filters? I can find normal centrifugals easily.

Christian.

Reply to
Christian McArdle

I would always put in an extractor in a modern house, or an old house that has been modernised. This is because there is not the level of airflow in that you would find in an old house becase of all the drafts, from windows, doors, gapped floorboards etc.. not to mention the forced draft caused by the chimney. Because of all this the smells (aromas if you like!) from cooking will hang around a lot longer - I think this is enough reason to install a cooker hood.

From a building maintenence point of view you don't really want all the moisture that is generated by cooking hanging around in your house either.

Even if you are not cooking meat you will still be using vegetable oils, I expect, and this is IMHO the main source of the muck that is collected by a cooker hood.

A hood also takes away some of the excess heat that is generated from cooking. In general this can make the kitchen too hot or make the AC work harder than it needs to; so another good reason to install a hood.

The only negatives that I can see are the extra electricity used for the light and fan, and the draught and cooling effects, minimal.

I'm no expert, these are just my opinions, but I hope that I have been some help.

Chris

Reply to
Chris Harris

Take that as read. It's a kitchen extractor I'm looking for.

No carbon filters or other filters remove all the grease and over time it may build up in the flue. Another important point is the steam produced by cooking. This reacts with the carbons from any old soot and produces an acid which may leach through the chimney breast and cause brownish stains. A liner would prevent this. This is well documented on the web.

Anyone know a site that has kitchen extractor boxes without design features such as a hood?

Reply to
Suz

This is the sort of thing I'm looking for. I'm certain you can get it as there was one in a friends house when she moved in.

I think you definitely need a extractor. In short, steam and smells. Will make for a much more pleasant environment. I don't think it would be a good idea to have the steam constantly in the chimney breast with nowhere to go, unless it is well sealed all round to keep damp out.

Can I ask why you blocked the flue off? You need to watch the chimeny breast above doesn't get damp. If you close up a chimney breast you are suppose to have a vent to let air circulate and prevent damp. Causes a horrible draught though.

Suz

Reply to
Suz

The problem is due to lack of space. The available space within the flue for mounting is a brick's depth, a fairly generous width and about a foot in height. I think a 100mm hole will also weaken the wall considerably, so something that can take a smaller bore than the standard 100mm would be good.

It wasn't me. The chimney from the kitchen rose through bedroom 3. This was removed by previous owners as the extension of the upstairs bathroom caused the chimney to jut out right next to where the door had been moved to. The chimney stack is now chopped off in the loft space. The chimney in the kitchen was untouched.

Since I moved in, we have opened out the hole to be big enough for a 90cm range cooker. (10cm wider and 80cm taller than it was). Looking up what remains of the flue, we can see the floorboards in bedroom 3 above. Obviously, we need to block this off more effectively to prevent smells rising.

The only stagnant air will be between the multiboard and the floorboards, which are very gappy. I can't see it being much different to a standard floor cavity, with plasterboard and little ventilation.

It'll be well sealed. The only thing is that I've never really used kitchen extractors simply because every single one I've encountered has been a "recirculating" type (read: completely f***ing useless).

Christian.

Reply to
Christian McArdle

You also don't particularly want all that grease in your a/c filters or in your a/c - either.

Reply to
Simon Gardner

I wish.

Christian.

Reply to
Christian McArdle

So true. Crappy one in our house put in by previous owner. You might as well flap a carbon filter in the air for all the good it does.

My mother has a properly vented one and it's great for removing steam, and therefore humidity on high pressure occasions like Xmas dinner. It's really powerful. If we get one like that, hubby says we'll have to tie bricks to No 2 daughter's ankles as she might get sucked out. Poor wee skinny-ma-link.

Reply to
Suz

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Reply to
dave

Does the chimney breast back onto an exterior wall (i.e., not in the moddle of the building)? If so, why not have the extractor blowing into a horizontal duct pipe which passes horizontally through the chimney breast, termonating in a ventillator grille on the exterior of the building?

Frank

Reply to
Frank Watson

No, it is slap bang in the middle of our party wall with the semi next door...

Reply to
Suz

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