| Why a cooker hood
and why Elica
Choosing a Cooker Hood
Types of cooker hood available
Installation in the re-circulating mode
Installation in the ducted mode
Types of ducting
Cooker hood problems on
Elica are the world's No 1. They are the company that manufactures
for most of the recognised brand names. Elica, the brand exclusive
to D R Cooker Hoods, the Company that have pioneered the product
for over 25 years. A Company, that all our customers have come
to rely on for a wide range of stock and after sales service.
Steam created by the cooking process can cause unpleasant wet walls
and furniture. It makes the kitchen a less pleasant place to be
for both the cook and the family. In extreme cases mould can form
on decorations and kitchen units can be affected so much that doors
jam and carcasses bulge as they absorb water. Wallpaper may peel
away and the joints become obvious.
Strong smells created by the cooking can spread throughout the
house; onions in the boudoir may clash with the talcum powder!! Cooking
oils may be vaporised when frying and this oil can be deposited
in all areas around the cooker. The décor suffers and redecorating
is required sooner than should be necessary.
With so many new properties having a combined kitchen/dining room,
the need for a hood has never been greater.
When kitchen planners design a new kitchen, they don't ask their
customers "do you want a cooker hood?" they ask, "What
type of hood do you want?" They would not plan a kitchen
without a fridge and they no longer plan a kitchen without a hood.
A cooker hood will, if installed with ducting, extract from the
kitchen virtually all the steam and strong cooking odours. It
will also collect on the disposable or washable grease filters,
all the airborne grease created whilst cooking. Also of course,
when foul air is extracted, fresh air must come into the room to
replace it. This process is expressed by air changes per hour.
For all these good things to happen, then many conditions must
apply. The hoods must not be too noisy or people will not switch
them on. High noise levels can be tolerated for short periods
on high speed; low speed must be reasonably quiet, therefore no
more than 55Db maximum.
The hood must be ducted to the outside of the house using the correct
size ducting, which is determined by the ducting diameter of the
hood. There is now available such a good variety of ducting in
flexible and rigid form that cooker hoods in most installations
can be ducted out even if the wall upon which it is mounted is
not an outside wall.
The hood must be powerful enough to change the air in the kitchen
ideally 12 times per hour, but at least 8. To calculate the volume
of the room, multiply length x width x height. An average room
is approximately 25m3; therefore the extraction rate required for
the average room is 200 to 300m3h. The minimum required as specified
in the building regulations for new kitchens effective April 1990
Room Size and Required Airflow Calculator
When ducting is impractical or there is no apparent problem of
condensation in a kitchen that is already well ventilated, then
the hood may be installed in the re-circulating mode. In this
case the correct charcoal filter must be fitted and replaced periodically
at the intervals specified by the manufacturer.
Some models now have available washable charcoal filters that can be cleaned in the dishwasher. These are effective for 3 years or more if washed on a regular basis.
When a hood is fitted in the re-circulating mode, it will be less
effective than if it was ducted out, but it will still: -
Collect all the airborne grease at the source, therefore preserving
Weaken the cooking odours so that odours are largely confined to
the kitchen area.
Dissipate the steam so preventing localised damp patches in the
One of the key things to consider is style and look. But to ensure
your choice gives optimum performance it should be at least as
wide as your oven or hob. Will your choice be ducted to the outside
of the house? If so, the ducting needs to be the right size; a
cooker hood installed with the correct ducting will extract virtually
all the steam, cooking odours and airborne grease from the kitchen.
If however, it’s impractical to install ducting in your home,
then charcoal filters can be used to re-circulate fresher air around
the room. Whichever method chosen, Elica adopt only the latest
European standards when measuring the efficiency of their products.
That’s why Elica cooker hoods are recognised around the world
for their unsurpassed performance.
The Free-standing cooker hood, usually supplied with charcoal
filter included, are at very competitive prices and are available
in 60 and 90cm widths. These may be single or twin motor.
The Integrated cooker hood, most popular size 60cm. These models are only used in fitted
kitchens. They are always fitted between wall units and have a
door on the front, which matches the other kitchen furniture and
effectively hides the appliance except when viewed from below. Opening
and closing the door switches the fan on and off at the speeds
previously set and also activates the cooker hood lights to illuminate
the cooking surface. Very popular with the kitchen trade and price
is usually included in the basic cost of the kitchen.
Built In and Canopy Hoods are fitted into the base
plate of wooden or metal canopies. Available in both 60 and 80cm
widths, with single or twin motors. These models are only visible
when viewed from below as they are generally fitted into specially
made decorative canopies.
Ceiling Mounted Hoods are feature hoods that are installed onto a ceiling, (which has be reinforced to take the weight) in an Island situation or above a hob that has been installed on a run of bass units against to the wall
Ceiling Hoods are similar to Built In hoods, only they are much bigger and need to be more powerful as they are generally installed much further away from the hob and come with a remote control unit.
Chimney and Island Hoods are highly visible, high
tech models that are used as features within the kitchen. Usually
much more expensive than the other types of hoods. These hoods
mainly feature halogen or fluorescent lamps and very high performance
fan motor systems. Accessories such as spice racks, utensil rails
and back plates are available to enhance the appearance of these
Classic Canopy and Cove designed to enhance
range style cookers. Available in 7 colours and stainless steel.
Downdraft Hoods are installed into the worktop behind the hob.
Problems are very rare when no ducting is involved, but of course
there must be first a paper, fibre or aluminium grease filter,
and secondly a charcoal filter. There must be a clear gap between
these two filters, if not then grease will quickly contaminate
the charcoal filter, rendering it useless within a very few weeks.
Grease filters should be cleaned or replaced every 3 or 4 months,
and charcoal filters at around 18 months according to the amount
of hob cooking time.
Choosing and Installing the Correct Ducting
Because it is normally hidden, a ducting system is often not considered
an important part of the construction or refurbishment of a building.
However, the importance of the correct ducting is slowly becoming
recognised by the building industry.
It is not always the fault of the cooker hood when dreams of fresh
rooms and low noise fans are not achieved. It can often be that
the wrong size ducting or wrong configuration has been selected
by the installer or by the system designer.
Air movement is often made more complicated than it actually is.
Air moves just as water moves and it is sometimes useful to visualise
a problem by substituting air with water.
In ventilation installations the aim is normally to move the air
from its source to the outside of the house as efficiently and
quietly as possible. It is, therefore, common sense that to do
this effectively, the shorter the distance the air has to travel,
the quicker the aim is achieved. It is also common sense that if
an obstacle is put in the way, such as a bend, the process will
become more difficult as the air will lose its momentum and may
require more powerful assistance in order to achieve the aim.
Cooker hoods vary in power just as cars do and the results are
reflected in much the same way. A high performance/specification
car should be quieter, last longer and generally provide the driver
with more comfortable and satisfactory results. However, to ensure
this, the car needs a straight smooth road on which to travel effectively.
The road for the air to travel when using an extractor fan is the
ducting. Again, it is common sense that a more powerful fan would
need a more efficient duct - a Rolls Royce owner would not consider
driving their car in off-road conditions! It is worth remembering
that the manufacturer’s guarantees will be invalidated it
the correct size of ducting is not used to match the power of the
A few key installation guidelines can be applied to help ensure
that the ducting selection is correct and installed in a way that
optimises the extractor’s performance.
||Choose the shortest and most direct route to the outside
or the point where the air is to be released.
||Ensure that bends are kept to a minimum.
||Check the extraction capability and connection size of
the hood and choose an appropriate size duct. Refer to the
Model for performance ratings. DO NOT, UNDER ANY CERCUMSTANCES,
REDUCE THE DUCTING SIZE. If the hood outlet is 150mm (6”)
then the ducting must be of the same area.
||Air travels better through a round duct, as the air will
travel at a lower speed, resulting in
less turbulence, vibration, noise and energy loss. However,
the installation space
available may prevent this ideal.
||A rigid duct is more efficient than a flexible duct and
should be used whenever possible.
||If flexible hose is used, the hose should remain taut and
as straight as possible.
||Special consideration should also be given to the selection
of the wall terminal and the
use of back draft dampers, as these also increase air resistance.
Round Pipe Ducting
A round duct provides optimum airflow performance and should be
used if installation space allows. We have a selection of bends
and adapters to meet most installation requirements.
Rectangular Ducting (Flat Channel)
Rectangular or flat channel ducting is an excellent alternative
when space is restricted. Its low profile enables the ducting to
be easily concealed in the ceiling void or along the top of
wall units. We have a selection of bends and adapters to meet most
Flexible Hose Ducting
Flexible hose is available in round and rectangular form, to complement
the rigid systems. It provides a solution to overcome awkward situations
where a rigid system cannot be installed. Flexible hose is most
effective for slow moving air, such as with tumble dryers, but
can be used with higher volume appliances (with due care taken
to ensure that its use is limited and that the hose is kept as
taut and straight as possible). 8
As has already been explained, the performance of the fan is dependent
on the performance capability of the hood itself, the size of the
duct, the ducting configuration and the type of wall terminal installed.
Each ducting run can be planned in advance and its performance
levels evaluated so it can be ascertained if the desired installation
will meet the required level. Technical data is available for the
cooker hood installer or system designer in order to achieve the
optimum overall extraction rate.
Before calling a service engineer, check that the electrical supply
is plugged in and switched on, if ducted to the outside of the
house, check that; -
Ducting is of the correct diameter if round. Or an equivalent area
The ducting is not kinked or pinched anywhere along the whole length.
If there is a back draught shutter installed, at either end of
the run, it is properly located and opens and shuts when the fan
is switched on and off.
There is no rubble or even a draught stopper that has been fitted
while waiting for the cooker hood to be installed.