My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal fans
"suck" compared to blowing? I have a vague feeling that they suffer from
blade stall with even slightly reduced pressure, but I can't find any
useful info.

On 28/12/2019 21:28, wrote:
My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal fans
"suck" compared to blowing? I have a vague feeling that they suffer from
blade stall with even slightly reduced pressure, but I can't find any
useful info.

It will be fine

On Saturday, 28 December 2019 21:28:22 UTC, wrote:
My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal fans
"suck" compared to blowing? I have a vague feeling that they suffer from
blade stall with even slightly reduced pressure, but I can't find any
useful info.

Make sure the ductwork can be cleaned out.

On Saturday, 28 December 2019 21:28:22 UTC, wrote:
My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal fans
"suck" compared to blowing? I have a vague feeling that they suffer from
blade stall with even slightly reduced pressure, but I can't find any
useful info.

the difference is trivial

Wrote in message:
My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal fans
"suck" compared to blowing? I have a vague feeling that they suffer from
blade stall with even slightly reduced pressure, but I can't find any
useful info.


Do you actually need a filter on an extractor ducted to outside?
--
__
%Profound_observation%


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Graham. wrote:

Wrote in message:
My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal fans
"suck" compared to blowing? I have a vague feeling that they suffer from
blade stall with even slightly reduced pressure, but I can't find any
useful info.


Do you actually need a filter on an extractor ducted to outside?

I suppose it may depend on how you cook, but the danger without a filter
is that the duct, the fan and the outside wall below the outlet will get
covered in thick brown rancid fat.


--

Roger Hayter

"Roger Hayter" wrote in message
...
Graham. wrote:

Wrote in message:
My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box
on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal
fans
"suck" compared to blowing? I have a vague feeling that they suffer
from
blade stall with even slightly reduced pressure, but I can't find any
useful info.


Do you actually need a filter on an extractor ducted to outside?

I suppose it may depend on how you cook, but the danger without a filter
is that the duct, the fan and the outside wall below the outlet will get
covered in thick brown rancid fat.

No filter on mine. Yes, the inner shutter does get
pretty grubby and so does the outer grill but trivial
to take them off and put them in the dishwasher.

Nothing ever ends up on the wall below the outside grill.

On Tue, 31 Dec 2019 04:50:48 +1100, Ray, better known as cantankerous
trolling senile geezer Rodent Speed, wrote:

I suppose it may depend on how you cook, but the danger without a filter
is that the duct, the fan and the outside wall below the outlet will get
covered in thick brown rancid fat.

No

LOL

Nothing ever

LOL

--
Kerr-Mudd,John addressing senile Rot:
"Auto-contradictor Rod is back! (in the KF)"
MID:

On 30/12/2019 14:40, Graham. wrote:
Wrote in message:
My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal fans
"suck" compared to blowing? I have a vague feeling that they suffer from
blade stall with even slightly reduced pressure, but I can't find any
useful info.


Do you actually need a filter on an extractor ducted to outside?

It's designed to have aluminium mesh filters and would look bad without
them.
In my last house the filters looked and felt "manky" after a while so we
put them in the dishwasher every couple of months.

On 30/12/2019 14:40, Graham. wrote:
Wrote in message:
My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal fans
"suck" compared to blowing? I have a vague feeling that they suffer from
blade stall with even slightly reduced pressure, but I can't find any
useful info.


Do you actually need a filter on an extractor ducted to outside?

It's designed to have aluminium mesh filters and would look bad without
them.
In my last house the filters looked and felt "manky" after a while so we
put them in the dishwasher every couple of months.

Oh mine does have its aluminium mesh screen in place and that's easy
to clean. I thought a "filter" would be some kind of disposable
activated charcoal cartrige.

--
Graham.

%Profound_observation%

Graham. Wrote in message:
On 30/12/2019 14:40, Graham. wrote:
Wrote in message:
My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal fans
"suck" compared to blowing? I have a vague feeling that they suffer from
blade stall with even slightly reduced pressure, but I can't find any
useful info.


Do you actually need a filter on an extractor ducted to outside?

It's designed to have aluminium mesh filters and would look bad without
them.
In my last house the filters looked and felt "manky" after a while so we
put them in the dishwasher every couple of months.

Oh mine does have its aluminium mesh screen in place and that's easy
to clean. I thought a "filter" would be some kind of disposable
activated charcoal cartrige.


Nah usually they're only used on recirculating setups to attempt
to absorb "smells".
--
Jimk


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

On 31/12/2019 14:29, Graham. wrote:
On 30/12/2019 14:40, Graham. wrote:
Wrote in message:
My cooker sits in what was once a fireplace and there is insufficient
height for a conventional "chimney-style" extractor. I've picked-up an
ex-display extractor and dismantled it, with the aim of fixing the S/S
rectangular part (with filters) over the cooker and remote-mounting the
centrifugal fan unit. The question is whether to put the fan in a box on
the outside wall (so it's sucking the 800mm from the filter box) or to
make some sort of "power bulge" in the 5" ducting (nearer to the filter
box) and blowing the rest of the way.
Before I do some experiments, does anyone know how well centrifugal fans
"suck" compared to blowing? I have a vague feeling that they suffer from
blade stall with even slightly reduced pressure, but I can't find any
useful info.


Do you actually need a filter on an extractor ducted to outside?

It's designed to have aluminium mesh filters and would look bad without
them.
In my last house the filters looked and felt "manky" after a while so we
put them in the dishwasher every couple of months.

Oh mine does have its aluminium mesh screen in place and that's easy
to clean. I thought a "filter" would be some kind of disposable
activated charcoal cartrige.

Mine has a flap that can be moved during installation to give
recirculation or to exhaust through the wall. The filter consists of two
layers on top of each other - the first filters fat to stop the interior
(and the ducting, if any) from becoming coated and the second removes
odours. If exhausting through the wall, only the first layer is required.

SteveW