Author Topic: Is it possible to put an extractor fan into a chimney? (Read 13478 times)

Jukes Mum · « **on:** March 08, 2016, 08:36:34 am »

We need to fit an extractor fan into the kitchen due to seam/damp issues.
The problem is the structure and layout of the room. The only place we can see that we could put one is above the cooker (which is logical) but this would need to be vented into the chimney. The chimney was used for the aga, which has now gone :-(.
Would it be possible to drop a liner down the chimney and vent the fan into the chimney?

MAK · « **Reply #1 on:** March 08, 2016, 08:50:19 am »

If you do not intend to light fires under the chimney then I don't see why you could not use it as a conduit. The only reservation I would have would be the length of any ducting and the temperature difference between that in the chimney and the warm moist air you are extracting. Condensation.
The unused chimney may have an air brick low down to ensure air flow and reduce possibility of damp.
It may be easier and cheaper to knock a hole in an external wall and fit a small extractor fan.

Louise Gaunt · « **Reply #2 on:** March 08, 2016, 10:59:09 am »

Is it possible to put some sort if fan into a window pane? We had two window mounted ventilation things in our kitchen in Guernsey. They were either open or closed, and wind drove the fans round giving air flow and ventilation.

Jukes Mum · « **Reply #3 on:** March 08, 2016, 12:08:24 pm »

Condensation was my thought. The chimney contains three flues. The flue we intend to use was for an aga which is no longer there, so no, there would not be a fire there. The next flue is for the living room. In autumn/winter/spring the woodburner would generally be lit in the living room while we are cooking so the flue should be warm (hence my thought that we should have a proper liner in the chimney, rather than just run a the flexible plastic extraction tube up there). However, in the summer, the flue will be cold, so would the steam make it all the way to the top, or would it condense in the ducting and just dribble back down again?
External wall is not really an option as they are too far away from the stream cooker, the walls are too thick and crumbly etc. I'd prefer not to have one in the window as it is such a cold room and we have suffered a window fan previously

bazzais · « **Reply #4 on:** March 09, 2016, 06:53:56 am »

It would be worth contacting an engineer as if you have other items in the house like burners or boilers you could be potentially altering the air flow through their venting systems to reverse or become less efficient.

Unfortunately you need to have 'draughts' as some call them - they are needed for safe operation of fires and extracting systems.

pgkevet · « **Reply #5 on:** March 09, 2016, 04:16:35 pm »

It depends much on the type of chimney. If it's a real brick type chimney and not structural to the house then shove a fan right through and out the wall and duct through the chimney rather than up..but don't forget you need a vent into any sealed chimney as well for the condensation reasons given. If it's just a steel flue type thingy then possibly removing it and elbowing out through the wall for a short run could work.

Jukes Mum · « **Reply #6 on:** March 10, 2016, 12:52:01 pm »

Its a brick chimney and structural.
The photo isn't good but the only one I could find. The kitchen is in the lower section of the roof (the single storey part of the house) and vents through the middle chimney pot.

pgkevet · « **Reply #7 on:** March 14, 2016, 09:12:52 pm »

I'd have thought you could shove a 6" duct straight through the middle of a 3 pot chimney to the outside.. although you will still need a plaster vent above that going into said chimney. But I'm not a structural engineer.