Ducting for Island Cooker Hood

[sergeantash]

I'm refitting my kitchen and have just fitted a 2m rectangular 125mm duct to provide a new island cooker hood with an external extraction route - however having now looked at some hoods, many seem to require 150mm ducting?

For such a short run, does this matter and can I simply use a reducer from 150mm to 125mm? The only angle in the duct route is where it turns 90 degrees downwards from the ceiling for the hood itself.

 

[PrenticeBoyofDerry]

What do the hoods manufactures instructions state, in regards to duct requirements?

 

[sergeantash]

What do the hoods manufactures instructions state, in regards to duct requirements?

The expensive hoods all just state "150mm Duct", they don't really go into detail although I haven't been able to thoroughly check a manual yet.

 

[jj4091]

Opinion on this matter seems to be divided, personally I can see no problem with using reducers as simple physics dictates that the only difference there can be is that the air flow speed rate is increased.

 

[sergeantash]

Opinion on this matter seems to be divided, personally I can see no problem with using reducers as simple physics dictates that the only difference there can be is that the air flow speed rate is increased.

I totally agree - ok I'll press on Thanks for the help.

 

[sergeantash]

Thanks to those whom gave advice back in 2012 concerning this extractor, I have now found the time to fit the thing and have a few issues which you can hopefully help with:

http://www.diynot.com/forums/electrics/cda-island-extractor-not-sucking.369397/#2811546