Puzzling cooker hood problem

[Thejobsagoodun]

I have a Neff cooker hood that is correctly sized for the gas hob it sits above. It is a replacement for an older no-name unit that was getting a bit "tired".

The hood seems powerful and there is a good flow of air coming out from the external vent but here's the puzzling thing. Even at full speed the cooking fumes or steam spill out around the front and sides of the unit. This still happens if the mesh filters are removed to give an unimpeded pathway. When I checked the flow with a smoke taper the smoke plume seemed "lazy" compared to the previous unit's extraction performance. The duct is clear and clean.

Can anyone throw light on this odd problem? Thanks.

 

[Burnerman]

If there's a good flow of air coming from the vent, then obviously the fan is doing its job.....is there any obstruction within the cooker hood motor and grilles which could cause the fan to suck from another area? Presumably the recirculating filter has been removed!
The only other thing I can think of it that the unit is too high above the hob, but you say you aren't happy with the smoke test you did.
John

 

[Burnerman]

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[jj4091]

When you say the steam spills out the front & sides is this making you think there is a problem or is the steam condensing on things close by. The reason I ask is that it is normal for a vortex to form around the edges of the hood which makes steam swirl before it is re- sucked into the hood. You may find it does not happen as noticeably on a lower speed.

 

[bernardgreen]

Some extractors extract from the periphery of the hood while others extract from the centre of the hood.

Extracting from the periphery can be much more effective at trapping and extracting fumes and steam but tends to be noisy with higher air velocities involved.