Downward extractor ducting

[WWilts]

What do people do for downward extractor,

 

1) to duct the fumes to the exterior

2) to house the motor externally

Trying to picture what ducts need to be put in at foundation masonry stage

 

[PeterW]

If you mean a downdraft hob then they most likely recirculate. You need to know what hob you want to plan it into the kitchen - some of them the motor is huge. 

[WWilts]

Hoping to achieve externally mounted motor (less noisy), and discharge of extract to exterior. But not sure where to put ducts and what ducts (& whether underslab or not)

 

 

[PeterW]

Just now, WWilts said:

Hoping to achieve externally mounted motor (less noisy), and discharge of extract to exterior.

Motor isn’t the main source of noise - the air flow is. Is the kitchen on the ground floor ..? If so you will have issues with ducting as you don’t want to create a “U” that can collect condensation / fat etc.   

[WWilts]

Kitchen on ground floor.
Assuming that recirculation extractor will have limited extraction capability, how would one allow for stronger extraction as a backup?

Edited September 6, 2021 by WWilts

[WWilts]

"TD Silent" extractor fan on kitchen wall seems to be a reasonably good, quiet backup. Backup to a downward draft (recirculation) extractor on kitchen island. 

Anybody used a TD Silent extractor fan?

[Mr Punter]

Yes I have one for my hood over the cooker.  The fan is mounted in the space above the kitchen.  I removed the original fan motor from the canopy and connected a TD Silent 500 150 with 150mm rigid ducting, with flexi where it links to the fan.  I used a REB 1-N speed controller to operate it but it was rubbish and the fan would stall on low speed.  I swapped this out for a wall mount switch.  I think the new fans have 3 speeds.

 

I use the lights on the original canopy.  The fan is really quiet and brilliant at extracting.  You need big ducting.