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Post by DIYDafty on Nov 26, 2019 14:24:30 GMT
Hello all
I'm planning how to fit a cooker extractor that will vent to outside. It comes with a 150mm bit of ducting. I'd really rather not have to core drill a 150mm hole in the cavity wall. I was wondering if I used a reducer would I be breaking any regs? I looked at Part F but would take me the rest of the year to understand it but what I don't want is some bod from the council coming in moaning about it in years to come.
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Post by DIYDafty on Nov 26, 2019 14:31:53 GMT
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Post by DIYDafty on Nov 26, 2019 15:23:52 GMT
Hmm maybe I haven't. Seems there is a lot more ducting available at 100mm and that would mean a smaller hole too. Should I go down that small and do reducers 150 to 100 exist?
Sorry for all the posts !
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Post by tomplum on Nov 26, 2019 16:25:32 GMT
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Post by DIYDafty on Nov 26, 2019 16:45:51 GMT
Thanks Tom. That looks good but how do I get onto that 100mm pipe? The fan comes with a length of flexi 150mm .
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Post by rocketmanbkk on Nov 26, 2019 16:49:08 GMT
I’ve only ever seen one where you can core 127mm
150mm sounds big
Have you bought it?
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Post by battle1066 on Nov 26, 2019 17:27:26 GMT
The last one I done required the 150 mm hole and the instructions stated do not reduce down, so read what the fan info requests DD.
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Post by DIYDafty on Nov 26, 2019 17:54:54 GMT
I've bought the fan already and it has a 150mm outlet but pretty sure it doesn't say don't reduce down. BUT if some are saying that maybe I shouldn't drastically reduce down so maybe going to 120 and not 100 might be the way to go.
Presumably the core 127 would be good for 120 pipe.
Thanks all for input.
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Post by battle1066 on Nov 26, 2019 18:27:03 GMT
I've bought the fan already and it has a 150mm outlet but pretty sure it doesn't say don't reduce down. BUT if some are saying that maybe I shouldn't drastically reduce down so maybe going to 120 and not 100 might be the way to go. Presumably the core 127 would be good for 120 pipe. Thanks all for input. The fan unit I installed has an indicator for cleaning and I assumed reduction = back pressure and the change filter light would come on. The core size will be fine - For me the disadvantage of a neat hole is the external plastic grills are easily distorted and come summer they crack if installed stressed. |
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Post by jcplumb on Nov 26, 2019 18:30:52 GMT
From what I understand, when you reduce it down you're creating a section where the flow is interrupted and water vapour will condense and pool there, that will end up being ideal breeding grounds for nasties such as legionella.
To be fair though water is going to pool along the bottom of the pipe whether there's a restriction or not.
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Post by tomplum on Nov 26, 2019 18:31:43 GMT
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Post by DIYDafty on Nov 28, 2019 23:09:57 GMT
Right done some more on this. We live on a busy road and cutting a hole in the wall is surely like having the window open when it comes to noise - that would be a disaster. So at last minute (because I'm a dafty) I changed my plan a bit and have now decided to go through the ceiling and then out through the soffit. That means 100mm. I did some bench tests today connecting the hood to two reducers to get down to 100mm straight out of the hood. With 3M of 100mm ducting attached it doesn't make much more noise and my "scientific" tests show that it still blows like buggery at the end even with lots of bends. So that is what I'm gonna do. Cover up the narrow ducting with the supplied decorative flue plate. No core drilling and certainly no core drills to buy and job's a gooden' for this Dafty  |
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Post by tomplum on Nov 29, 2019 21:19:23 GMT
whatever works is good dafty,  |
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