Kitchen Extractor Fan - connecting different diameter flexible pipes

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Prosper

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Hi folks,
I bought new kitchen cabinets and a new extractor fan from IKEA at the end of January and I used their contractor in Dublin to install everything. Recently, I noticed the smell of cooking in the bedroom above the kitchen. I removed the built-in wardrobe in the corner of the bedroom to get a clearer view of the old piping (please don’t say I was mad to remove the wardrobe – I know that – but in my defence I also wanted to see if there might just be enough space to fit a small shower in there – stupid I know!!). If you look at the attached photo’s you’ll have a clearer understanding of the issue. The routing of the piping from the old original extractor fan has not changed. The only difference is that the Wavin piping you see in the skip bridged the gap between the old extractor fan and the flexible piping coming through the floorboard of the bedroom and down through the ceiling board of the kitchen. As you can see the IKEA installer used duct tape to join the old flexible pipe (110mm diameter) to the new IKEA aluminium flexible piping (125mm diameter). I’m about to replace the old flexible piping with a length of new PVC flexible piping and duct tape it to the aluminium one on the assumption that the only reason the duct tape used by the IKEA installer didn’t hold was because it was trying to adhere to a very old, dirty and dusty flexible pipe. However, the small difference in diameter could be a problem but maybe there’s an adaptor out there that would join up the two flexible pipes.
Another option is to use a piece of the hard Wavin pipe to bridge the gap between the new PVC flexible pipe that I will attach to the vertical Wavin pipe that takes the extracted air up vertically and out through the roof (you can see this vertical Wavin pipe in the space between where the wardrobe used to be and the hotpress) and the aluminium IKEA piping attached to the extractor fan. This solution might work better with the use of an adaptor because I could very well secure each flexible pipe to the adaptor using a high adhesive sealer – more secure than duct tape. Here’s an adaptor I saw online https://www.i-sells.co.uk/125mm-to-100mm-reducer The only problem is that the gap between the top of the wall hung cabinets and the ceiling is only 117mm so not much room to work in.
Anyone any thoughts before I start?
 

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Prosper said:
the assumption that the only reason the duct tape used by the IKEA installer didn’t hold was because it was trying to adhere to a very old, dirty and dusty flexible pipe. However, the small difference in diameter could be a problem but maybe there’s an adaptor out there that would join up the two flexible pipes.
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Not all duct tape is created equally, there can be a vast difference in how well some of it adheres and lasts.

It's hard to tell, but it looks like the join between the larger and narrower ducts is just relying on the tape to bridge the difference. The airflow is likely pushing humid air against the inner surface of the tape, and that will cause it to deteriorate.

You can get https://www.amazon.co.uk/DUCTING-REDUCER-INCH-STRAIGHT-VENTILATION/dp/B004X4S7QI/ref=pd_sbs_60_2/258-8291876-9150029?_encoding=UTF8&pd_rd_i=B004X4S7QI&pd_rd_r=88d01169-6b5e-4eec-ad4b-fd879ddc2813&pd_rd_w=L4b4S&pd_rd_wg=Cfe4R&pf_rd_p=2773aa8e-42c5-4dbe-bda8-5cdf226aa078&pf_rd_r=H2E9EWTS9F4YCPMYWNWJ&psc=1&refRID=H2E9EWTS9F4YCPMYWNWJ (reducers) from 125-100mm, with that the 100mm end will fit inside the 110mm flexible duct, keeping the airflow moving in the right direction. Just tape that up with a good quality tape and you should be set!

Edit, you'll get https://www.amazon.co.uk/Reducer-Connector-Diameter-Ventilation-Universal/dp/B00N1ZTAMU/ref=asc_df_B00N1ZTAMU/?tag=googshopuk-21&linkCode=df0&hvadid=231908893094&hvpos=&hvnetw=g&hvrand=3977476250587670899&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007850&hvtargid=pla-422131935321&psc=1 (reducers) to 110mm as well, but I prefer the smoother reduction on the other one as it'll introduce less resistance to the airflow.
 
Leo said:
Not all duct tape is created equally, there can be a vast difference in how well some of it adheres and lasts.

It's hard to tell, but it looks like the join between the larger and narrower ducts is just relying on the tape to bridge the difference. The airflow is likely pushing humid air against the inner surface of the tape, and that will cause it to deteriorate.

You can get https://www.amazon.co.uk/DUCTING-REDUCER-INCH-STRAIGHT-VENTILATION/dp/B004X4S7QI/ref=pd_sbs_60_2/258-8291876-9150029?_encoding=UTF8&pd_rd_i=B004X4S7QI&pd_rd_r=88d01169-6b5e-4eec-ad4b-fd879ddc2813&pd_rd_w=L4b4S&pd_rd_wg=Cfe4R&pf_rd_p=2773aa8e-42c5-4dbe-bda8-5cdf226aa078&pf_rd_r=H2E9EWTS9F4YCPMYWNWJ&psc=1&refRID=H2E9EWTS9F4YCPMYWNWJ (reducers) from 125-100mm, with that the 100mm end will fit inside the 110mm flexible duct, keeping the airflow moving in the right direction. Just tape that up with a good quality tape and you should be set!

Edit, you'll get https://www.amazon.co.uk/Reducer-Connector-Diameter-Ventilation-Universal/dp/B00N1ZTAMU/ref=asc_df_B00N1ZTAMU/?tag=googshopuk-21&linkCode=df0&hvadid=231908893094&hvpos=&hvnetw=g&hvrand=3977476250587670899&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007850&hvtargid=pla-422131935321&psc=1 (reducers) to 110mm as well, but I prefer the smoother reduction on the other one as it'll introduce less resistance to the airflow.
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Thanks Leo. I'll fire ahead and get a 125-100mm reducer like the one in the link in my post and use good quality duct tape. Hopefully, the two horizontal runs before it gets to the vertical pipe isn't a problem.
Before I get a new wardrobe or whatever put back into the space I'm going to put Knauf Earthwool Acoustic roll in between the studs before I replace the plasterboard that was behind the wardrobe and also run it up along the vertical pipes. Apparently, the acoustic earthwool works better also as a thermal insulator when it comes to vertical application.
 
Did you report the lousy workmanship to IKEA? Ask them why their contractor didn't know of or didn't use the the interfacing unit and ask them for your money back.
 
mathepac said:
Did you report the lousy workmanship to IKEA? Ask them why their contractor didn't know of or didn't use the the interfacing unit and ask them for your money back.
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You bet I will. This wasn't the only issue. I won't go into it now but I will another time if anyone wants me to. Should've installed the units myself but I was doing other decorating stuff in the house and so paid them for install and additional works (moving/adding elec sockets, tiling) just to get it done faster.
 
Overall, how long is all this piping? I replaced my extractor fan last year and was annoyed that the previous installer had opted for the easier though less effective 5m route rather then the very effective 1m route, straight out through the wall. Your piping looks like it’s dozens of metres.

I had googled it at the time. The longer the piping and the narrow the diameter the less effective it is. I think 1m is the optimum length.
Is the extractor far from an external wall, so that you could put a hole in it and go straight outside?
 
Drakon said:
I had googled it at the time. The longer the piping and the narrow the diameter the less effective it is. I think 1m is the optimum length.
Is the extractor far from an external wall, so that you could put a hole in it and go straight outside?
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The horizontal run from the extractor to the hole in the ceiling board is 70cm and the run from there to the vertical Wavin pipe is 60cm. So a total horizontal run of 1.3 metres and from there it's a straight vertical run through the hard Wavin pipe up through the attic and out through the roof. The old extractor fan took exactly the same route and I had no problem with it for 32 years therefore I'm going to stick with that route rather than re-route it the 2.5 metres to the external wall. You're absolutely right that a greater diameter piping would be better as the new IKEA extractor fan is more powerful than the old one but I think if I get the join right between the 125mm IKEA ducting and the new 110mm PVC ducting I got in Woodies then I'll be happy enough with that. Before I do anything I'm going to wait until IKEA re-open and see what they say. When the extractor fan was delivered it came with 150mm flexible ducting. However the installer said this was the wrong diameter ducting and he used 125mm IKEA ducting. I checked the Underverk instructions and you can use 120/125/500mm ducting. So, if IKEA say to use the same diameter ducting all the way until it joins with the 100mm diameter vertical Wavin pipe then that's what I'll do.
 

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Prosper said:
The horizontal run from the extractor to the hole in the ceiling board is 70cm and the run from there to the vertical Wavin pipe is 60cm. So a total horizontal run of 1.3 metres and from there it's a straight vertical run through the hard Wavin pipe up through the attic and out through the roof. The old extractor fan took exactly the same route and I had no problem with it for 32 years therefore I'm going to stick with that route rather than re-route it the 2.5 metres to the external wall. You're absolutely right that a greater diameter piping would be better as the new IKEA extractor fan is more powerful than the old one but I think if I get the join right between the 125mm IKEA ducting and the new 110mm PVC ducting I got in Woodies then I'll be happy enough with that. Before I do anything I'm going to wait until IKEA re-open and see what they say. When the extractor fan was delivered it came with 150mm flexible ducting. However the installer said this was the wrong diameter ducting and he used 125mm IKEA ducting. I checked the Underverk instructions and you can use 120/125/500mm ducting. So, if IKEA say to use the same diameter ducting all the way until it joins with the 100mm diameter vertical Wavin pipe then that's what I'll do.
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Sorry that 500mm should read 150mm
 
Folks,
Below is the text of an email that I sent to IKEA today. I've deleted the name of their kitchen installation contractor. The acronym PIV = pre-installation visit. The reason I'm posting this is for any advice you have. I have a tendency to be too reasonable. They'll probably come back and say that their responsibility is just to install the extractor but not connect it to the old ducting. If that's the case, I certainly was never told this. Anyway here's the text of the email I sent. The photo's referred to are in my first post in this thread.

"I have a problem with the extractor fan installation. The join between the old 110mm diameter PVC flexible ducting and the IKEA Nyttig 125mm aluminium ducting was done using duct tape and it has separated. Having now read up on the issue I realize that using duct tape to join wider diameter flexible new ducting to old and dirty ducting is very problematic. The result is that I cannot use the extractor fan without the fumes and smell filling not only the kitchen itself but also the bedroom above the kitchen. This problem wouldn't have occurred if **** had used a proper method of joining the old PVC flexible ducting to the new IKEA 125mm flexible ducting. I've attached photo's so you can see the problem for yourself. Since the problem has occurred I have read up on the issue of venting extractor fumes to the outside. I now realize that it would have been better to get rid of the old PVC ducting altogether. This means connecting the IKEA ducting from the Underverk extractor all the way to the vertical Wavin pipe that takes the fumes up through the house and out through the roof. To facilitate this I've removed a built-in wardrobe in the bedroom above the kitchen in order to allow access to the start of this Wavin pipe. I'll not want duct tape used to connect the IKEA aluminium ducting to this pipe. This Wavin pipe is 110mm external diameter and so a "reducer" that on one side fits over this 110mm Wavin pipe and the other side the "reducer" will have to fit snugly into the 125mm IKEA ducting. Metal clips and proper sealant should be used for both of these joins.
My experience of getting this IKEA kitchen hasn't been a good one. **** must have had to join IKEA extractor fans with old extractor fan ducting many many times before. If there is a particular problem with this then I should have been informed when I ordered the Underverk fan and told that some preparatory works on the venting would have to be done. If not at ordering time then I certainly should have been told at the PIV of any possible problems. Maybe the reason I wasn't is because you're used to people trying to get works done for nothing. I'm not like that. For example as you can see from the copy/paste below, when **** quoted me for additional works I was honest and told him that his quote was missing the movement of two sockets and the result was that his quote for additional works went up by €150 from €630 to €780. Then when his electrician came we decided that one of these sockets didn't need to be moved. I didn't go back to **** looking for a partial refund. I could have demanded a €75 refund but I didn't. If at the PIV his colleague had advised me to change the ducting altogether then I would have gone with his advice and paid them to do so. But no mention was made of any possible problem. One of the reasons I paid IKEA for the installation was to avoid any problems and of course to be covered under warranty. Now that the kitchen has been installed the fixing of the problem is many many times more difficult than doing the job right in the first place. Apart from removing the wardrobe it looks like I'll have to cut and lift part of a floorboard in the bedroom and make a longer and wider hole in the ceiling board rather than take down the wall units in the kitchen in order to get working access to the ducting beneath the kitchen ceiling.
Would you arrange for Nyttig 125mm Tubing (p/n 600.899.85) to be delivered to me along with a 125mm diameter metal hose clip (or two just to be sure)."
 
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