Cooker hood extractor fan blowing not sucking

[tom23432]

We have a range master oven cooker hood that has an extractor fan venting outside.

I have confirmed there is no blockage in the ducting to the outside and I have made sure the ducting is fully secure to the top of the hood exit hole.

But for some reason the fan seems to be partially blowing air back around the hood, instead of fully extracting it up into the ducting.

Here is a video of what I am talking about: https://streamable.com/fyr38e

This is on max power.

If I put my hand there I can feel a lot of air blowing outwards, but the back three quarters of the fan area sucks up the air as expected.

This model has a recirculating option, but that is not the default and the only difference in setup is adding a recirculating output part on the top of the exit hole. I have been through the manual and there are no mentions of different settings on the fan for recuriculating or outside venting.

This is the hood we have https://www.appliancesdirect.co.uk/p/leihdc90bc/rangemaster-leihdc90bc-89.8cm-chimney-hood

Any suggestions welcome.

 

[Harry Bloomfield]

It looks as if what you are seeing/feeling is a certain amount of air vortex, as a result of the air being sucked out. The tissue definitely confirms the major airflow is extraction, and so nowt to worry about. I've seen a need to configure anything for recirculate, versus outside vent, other than adding the duct.

 

[tom23432]

It looks as if what you are seeing/feeling is a certain amount of air vortex, as a result of the air being sucked out. The tissue definitely confirms the major airflow is extraction, and so nowt to worry about. I've seen a need to configure anything for recirculate, versus outside vent, other than adding the duct.

Thanks.

I have taken a deeper look and removed the ducting from the top of the hood. See attached picture.

The install manual says use 150mm - 125mm diameter ducting. The connector part is 150mm width, in then tapers in and the inner ducting appears to be around 115mm. The actual entrance bit that where all that excess material is appears to only be around 85mm.

So from this my guess is that the ducting is insufficient and restricting it.

With the ducting completely disconnected from the top, if I run the fan at full speed I can feel it is sucking with a lot more power and there is almost no blowing back around the hood.

Looks like I need to get this sorted with some better ducting.