Cooker Hood Buying And Installation Advice

Cooker hoods are an often ignored appliance as it seems consumers buy these appliances based purely on style as they are always on display; in fact they actually often form a focal point in the kitchen along with the cooker or oven and hob combination. Many consumers seem to believe that, much like other appliances, that they are all the same as they do the same thing. This is wrong!

A cooker or extraction hood is designed normally to remove the cooking odours and airborne grease from the cooking process on the hobtop and if you expect the appliance to do that then do you honestly think that a hood costing little more than an Xpelair will actually perform that task? The short answer is that it will not. To obtain a proper cooker hood that will actually perform the task that it is actually there for is going to cost over £100, a lot more if you want quality and style as well as the performance that you may expect.

Cooker Hood Extraction Rates

Many manufacturers that make a decent hood will give the extraction rates in their literature, citing the value in CM2 or cubic meters, spared based on a set period, usually an hour and this allows you to determine the efficiency of the machine albeit under ideal conditions. Essentially the higher that figure is the better the extraction rate should be if the machine is installed correctly.

Cooker Hood Filters

Filters are one of the most important aspects of a cooker hood given that they are effectively filtering the contaminants out the air from the cooking process. Of course this becomes slightly less of a problem you may say if the hood is vented, as it should be, to the outside air, but even so you still have to stop the grease in the air from reaching the motor and fan assembly.

For starters consider the type of filters fitted to the hood you are looking at, are they fabric grease filters or are they a metallic matrix? With the paper or fabric filter you will have an ongoing cost to replace them and not replacing them will lead to degradation in the performance of the appliance over time, as well as being a health hazard providing a breeding ground for bacteria. By contrast the metallic grease filters, formed by a matrix of fine steel mesh that traps the grease from the extracted air and can be washed many, many times in your dishwasher with no loss of performance. So in effect the metallic filters are the better bet to save time and hassle over the life of the appliance as well as being a lot less hassle to maintain.

We are often asked for the cost of replacement carbon or charcoal filters which are supposed to remove odours from the cooking process. But carbon filters are not exactly efficient in the real world at this task and the only reason for having one fitted is if the hood is in "recirculation" mode which in itself is a bit misleading. Whilst in recirculation mode all the air from the cooking process is re-circulated into the room where the air originated! This is far from ideal. The whole idea of a hood is to remove the contaminated air from the room and, if the appliance is not vented to the outside as shown in the diagram, then the performance will be severely impaired to the point where the appliance becomes almost nothing more than decoration.

If you are looking for replacement filters you can visit this section of our online store which lists many of the most popular types and universal filters or, if you wish to track down a specific filter simply email us This e-mail address is being protected from spambots. You need JavaScript enabled to view it and we'll find it for you.

If the hood is vented to the outside air then remove the carbon filter, it is redundant and not needed, all it is doing is reducing air-flow in situ.

Without venting the appliance to the outside air the performance will not reflect the actual reason to purchase the device in the first place.

Cooker Hood Installation

So you now know that venting the machine to the outside air is paramount in the performance of the appliance but there’s more to the installation of a supposed "simple" device than that.

Yet gain I cannot reiterate the importance of reading the installation instructions thoroughly before installing any appliance and this is incredibly important with hoods. For example check out how far you can take the hose to vent the appliance and have it remain effective. There are many other factors to consider to, like is the vent hose the correct diameter, is the hood mounted at the correct height above the hood, if it's a gas hob this is vital to meet CORGI regulations, is the hood the correct width to extract the air properly as this c ould be vital if you cook to any degree. Also, very importantly, is the appliance accessible for service? If not you will run the risk of an engineer refusing to repair if required, should the appliance be tiled in, the mains supply is not accessible, there is a "flyover" preventing the appliance being taken down for service, these points are vital and have to be addressed before installation.

An example of proper cooker hood venting

An example of venting a hood along the top of the kitchen units properly.
Image kindly supplied by Elica


Most of all do not trust that the kitchen fitter to have the knowledge to install the appliance properly in accordance with the manufacturers instructions and if you want to ensure that the appliance performs the way it should then make sure that they do follow those instructions. No offence to kitchen fitters but we see poor appliance installations on a daily basis and it seems few install the appliances correctly.

Proper installation is vital, please pay attention to the instructions with the appliance and bear in mind that an incorrect installation is often a cost not borne by the manufacturer if you call an engineer should you perceive a problem. You may well be charged if there is no actual fault with the appliance and virtually all hood faults related to non-extraction are performance issues, not a fault.

Basic cooker hood installationAn ideal installation


One of the single biggest problems being encountered now with cooker hood installations today where they are vented to the outside air, is the incorrect size of vent used most commonly, or just general poor ventilation. These will both lead to the appliance seeming faulty but neither are an actual fault with the appliance, it is worth checking this as many manufacturers will not accept the cost of a call to tell you that the ventilation is incorrect.

From the Elica website:

Choosing and Installing the Correct Cooker Hood 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 hood.

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 CIRCUMSTANCES, 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.

Types Of Ducting 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 installation requirements.

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).

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.

Much of the above information is absolutely essential in allowing the appliance to operate as it should do and to actually expel the air from the cooking proccess.

Cooker Hood Lighting A typical modern cooker hood

There are lighting options and you have to choose this carefully dependent on the use of the appliance as many people use the lighting on the hood for extended periods of time which can put a strain on them, particularly conventional lamps where the space may not be ideal and heat builds up. Also on many lower cost appliances the holders are made from plastic and are not designed for extended use. The fad of the past few years has been for halogen based lighting on hoods which is a lot better in many ways, giving a clean and more natural light as well as being bright and concentrating the light on the cooking area offering a very nice focal point through lighting if that is the desired effect. Halogen lighting of course is also low-voltage lighting and runs using less energy as well as cooler than conventional lighting methods.

Also available are hoods with fluorescent lighting as well which of course offer extremely good efficiency and light output as well as running almost cold, so ideal for running for extremely long periods of time, but in most people's opinion not as nice looking as halogen lighting.

To the right you see the new "Ala" hood from Elica which uses fluorecsent lighting to great effect.

But the current trend is to break the mould a bit and do something different with hoods to make them more interesting and decorative that ever before, the use of stainless steel and glass is the current hot favourite as it is clean and decorative as well but new technologies in lighting are starting to appear. The next step should be a hood that uses LED lighting which is superb for the task as it is high tech, low-voltage, runs cold and has a very, very long lifetime and this may point the way to the future of hood lighting, only time will tell.

Direct Or Remote Cooker Hood?

There are essentially two types of motor setup for a cooker hood, a direct motor whereby I mean a motor and fan assembly mounted within the actual casing that you see and a remote setup, where the motor is mounted in a remote location and the case is really little more than a shell with grease filters.

Obviously the best one is the remote installation as the motor can be situated out of the way, in the attic for example, leading to far less noise in the kitchen and, as it would normally be fitted half way between the actual hood and the outside air, it is generally a more efficient method of drawing the contaminated air from the cooking area. This is often the method employed in a professional kitchen and the results of such an installation will easily demonstrate why that is. This is not to say that the direct hoods are poor relations as many domestic hoods are designed to be extremely efficient and good for the purpose, but the remote installation does have advantages that the direct machine cannot match, conversely, the direct hood is far easier to install and fits a wider range of installations so it really comes down to whether a remote hood is suitable and practical for your kitchen.

Cooker Hood Service Issues & Help Yourself

Most hoods consist of three basic components that will fail. A motor, a PCB and the lighting system.

Of course any of these spares we can supply for almost any brand of cooker hood in our online store

In general terms should one of these fail they will fail totally, I have yet to see a failure of one or any of these cause a performance related issue with a cooker hood in at least the past ten years and we receive at least six to twenty calls to hoods, a week! Of that I can almost guarantee that at least one or two will be with the complaint "not extracting well enough", this is a performance or installation issue and not a service issue, we cannot make the appliance perform any better than it does.

A simple test is to place a bank note, any denomination, on the filters when the hood is running at top speed, if it stays there then the hood is drawing air from the room. Beyond that there is very little a service engineer will be able to do to help you other than advice on the installation and, he'll probably be charging you for the call irrespective of whether the appliance is under warranty or not as this is not a manufacturing defect if the appliance is working.

If you feel the appliance is not drawing enough air from the room check that it is vented to the outside, you'd be amazed at the number of customers that do not know this or take account of it. If it is not then again, there's very little that an engineer can do, if anything at all. Change or clean the grease filters as that could be an issue and run any maintenance cycles as determined in the instruction leaflet.

You can purchase universal cooker hood filters from our store from this link

Other than that there is little self maintenance that can be done by the customer and, generally, a failure as stated, means that something just doesnt work and not that it doesn't work well enough.

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