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Hoods: how the filters clean the air

Work in the kitchen is often associated with a variety of, but not always pleasant smells. They’d fill your whole house if they weren’t opposed to an air cleaner, commonly referred to as a hood. One of the most important elements of this unit are the filters, and we will talk about them.

Extractor hoods

Every mode has its own filters

Modern cooker hoods generally have two modes of operation. The first is called a duct, in this case the appliance has an outlet in the ventilation shaft. Why are duct pipes connected to the hood and ventilation duct when installing.

The exhaust motor creates an air draft and the air filled with impurities, combustion products and smells is extracted from the room within minutes, preventing “leaks” into other rooms. This mode is more productive, and therefore efficient. Pressure drop leads to the fact that the kitchen gets fresh air.

For the way the air only flows through a hood, they’re called “ducted” hoods.

The second version of the hood is more labor-intensive, there is a loss of performance of the unit the air has more obstacles . It is called circulation or recirculation. This function draws air in from the kitchen volume, filters clean it and returns it to the room. The obvious disadvantage of such a system is the lack of fresh air supply – you have to breathe the “same”, although constantly cleaned volume.

However, such a hood is easier to install, you only need to place it on the project site.

For all their diversity, hoods consist of the same components:

– The most important one is the motor and appliances are available with two motors

– filtration systems

– fireplace or flat part

– ductwork

– control buttons, slider .

Better those that last a lifetime

A mandatory element of every air cleaner is a grease filter. Its task is to clean the streams of grease particles so that the internal parts of the hood motor blades, housing surfaces and piping are not covered with a layer of oil.

If filters hadn’t been invented, hood maintenance would have been a major challenge for homeowners. Suffice it to say that heated grease eventually turns into an olive-like substance that is surprisingly sticky, smelly and hard to clean.

So “Hail to the grease filters”! Without them the cooker hood motor would be damaged beyond repair. And when a hood is placed over a gas burner, a thick layer of grease inside the appliance can even catch fire.

Grease filters can be either disposable or reusable.

Disposable are filters made of synthetic materials: acrylic, fleece and sindepone.

They look like a light rug. Most commonly used in low-cost wall-hung hoods designed for under-cabinet installation, they’re also called “flat” hoods.

When dirty, the synthetic filters are discarded and replaced with new ones. Domestic housewives got used to wash them with powder or soap, but it is impossible to return the original properties to synthetics in this way, and such filters will not purify the air.

Reusable, or rather serving for the life of the hood, the filters are made of metal. They are used in most medium- and high-priced air purifiers.

Metal filters are of better quality, more reliable and safer. The metal filters do not need to be replaced washing them periodically is sufficient.

The metal changes – the essence remains

The filter is cassette-like and consists of a metal frame and a filter element. This is made up of several layers of perforated or wire mesh metal foil. There are symmetric and asymmetric perforations. The holes in the cells are necessary to maximize the free passage of air currents, their task is to change the direction of air jets. This traps and deposits grease particles on the filter surfaces.

Metal filters are most often made of aluminum foil or wire mesh, but can also be made of thin stainless steel sheet or galvanized steel. Elica extractor hoods are made of anodized aluminium that forms a very thin, passive layer that prevents oxidation.

The Spanish company SATA uses six-layer filters in its extractor hoods equipped with grease filters made of anodized aluminium that are not only more efficient in terms of protecting you from grease but also generate less noise. SATA uses 2 cassette filters which are easy to remove and have a proprietary latch with SATA logo.

ELIKOR hoods use filters made of five layers of anodized aluminium, which ensure 100% protection of the motor from grease particles without restricting the free flow of air at the same time.

The cooker hood usually has two or three filter cassettes instead of one large cassette. They are much easier to manipulate – to carry, remove and reinsert. They are more convenient to wash – they can be both in the sink and in the bowels of the dishwasher.

In addition, the presence of multiple cassettes, and hence planes, helps to find unusual design solutions, for example, in the case when the air intake zone has a curved shape.

Most extractor hoods are equipped with filters in the form of flat rectangles of various dimensions even more interesting and fancy designs use rectangular filters, such as Elica’s Om hood, which is hidden behind a temperatureresistant glass circle made of Isola Salina by Jetair.

The grease is picked up by the professionals

One of the market trends is the emergence of semi-professional hoods that use so-called “professional” grease filters made entirely of stainless steel.

These filters have several advantages over aluminum filters, including longer life, ease of maintenance because stainless steel is much easier to care for than aluminum and more effective air purification.

Elica uses filters that have asymmetrical arrangement of cells through which the air moves as a maze, so that most of the grease particles are trapped.

In addition, hoods using this professional filter have just one filter instead of the usual three aluminium ones in the 90 cm wide models and two in the 60 cm wide ones. This is made possible thanks to the optimized suction system of Elica.

Is there life without a filter?

The latest developments in the design of SATA’s premium suction hoods COR-L, Aeris Q4S, etc. are an important element of this design feature. , made a grease filter completely unnecessary.

With the Perimetric Draft, and thanks to its very high suction capacity, the aspirated air passes directly through the specially designed STQ 4 air handling unit, without having to clean any dirt in the grease filter while providing the motor with extra lubrication .

All of the grease will collect in the grease trap, which is easy to clean thanks to the Easy to Clean system. The absence of a grease filter in this design offers many advantages: the noise level can be reduced min. value of only 35 dB and save the consumer from replacing washing the filters.

If the air is circulating…

Hoods

The quality of the activated charcoal filter also has an impact on the performance of the hood as a whole. Usually in recirculation mode, its capacity is reduced by 20 percent, which is caused by the difficult movement of air inside.

In addition, the filter can be more or less dense. The air passes more and more slowly as it fills, so that cartridge replacement is not a caprice, but a necessary operation.

The charcoal filters tend to look different, even within the same manufacturer’s collection. This is due to the design of the housings on these models.

You can find filters in the form of a rectangular cassette, in a frame and with cells, or as a concave or flat round cartridge with a certain diameter it reminds you of a lid of some kind . The body is made of plastic, the charcoal is held in place by a grid.

The charcoal is taken in the form of small granules or powder.

The surface area of the granules affects the quality of the air cleaned. The higher it is, the more efficient the filter is. If the carbon is stacked too tightly or caked, this value also decreases.

It is interesting that 1 gram of fine powder of activated carbon has about 1000 square meters of surface.

Carbon filters are disposable. They are installed for a certain period of time, after which they are discarded. The “average” figures are 3 to 4 months. Everything is determined by the intensity of use of the device, one thing is half an hour daily, another is three to four hours.

Therefore, manufacturers give different recommendations as to how long this period should be: Elica every 2 months, Elikor, Jetair – 3 to 4 months, depending on culinary activity of the hostess, Falmec – 4 months, Fabriano – 4 to 6 months, Krona – 6 to 12 months, Gaggenau – twice a year, Bosch – once a year.

One simple method for prolonging the life of the activated charcoal filter is to leave the hood on for about 5 minutes after each use to remove the remnants of moisture from the filter, in this way the charcoal will retain its high adsorptive power for longer and will not cake.

There are long-lived charcoal filters!

Engineers thought it was wasteful to throw away almost a “new” filter every three or four months and invented those that can work longer.

Elica has developed filters that can be cleaned and regenerated Long Life Filter . The filter performs its function properly for three years.

True, you still have to wash it by hand or in a dishwasher every month. To wash the filters we use common detergents and choose the maximum temperature 65 C . Wash separately from the dishes so that they do not absorb any odors.

Then they’re sent to the oven… Dry at a temperature of 100°C for 10 minutes. This is where the “miracle” of activated charcoal regeneration occurs. After it cools down, the cassette is put back in place.

Facedown will be cleaner

Big appliances for the kitchen

Most kitchen hood owners have the pleasure of seeing the grease filters with their own eyes. After all, their task is to be the first to “take the hits”, so they are placed on the outside, on the bottom of the unit.

But there are some hoods e.g. Om Elica, Elikor Pomegranate, Franke FQD 907 XS, Kuppersbusch KD 9550, WSG and ARCUS4 Homeier in which the filters are hidden from our attention.

From an aesthetic standpoint, it’s understandable: It’s a lot easier to achieve the desired design effect without these lattice things. So the hood can be shaped like a pyramid or a flying saucer, a picture hanging down vertically or a wing.

You can access the filters in these appliances by opening or removing the doors or the decorative screen. After the necessary “service” has been performed, they are closed again.

The surface of such designs should be easy to clean from dirt and manufacturers always stipulate that. For example, using very smooth surfaces.

Although one of the basic conditions for such extravagances is accurate engineering so that air flows around obstacles, squeeze into narrow passages – slots – and are directed straight to the filter surface this is the so-called perimeter suction .

Wash the filter by yourself

One of the main tasks of a grease filter is to trap all contaminants before they attack the other surfaces of the unit and the air duct. In fact, this also means that it will be easier to remove them from the filter. In practice, care consists of a few simple procedures.

Step one. We remove the filters from the device – release the lock and pull out the cassette if the filter is closed by a decorative panel, you must first remove or open it .

Step two. We soak them in an aqueous solution of normal dishwashing detergent or put them in the dishwasher. In doing so, the holes should be vertical so that impurities can be easily washed away without clogging the cells. It is best to wash the filter “in the proud solitude”, without the company of dirty pots and plates. Manually rinse the filter with a sponge or brush and rinse under a strong stream of water.

Important. Despite the chemical resistance of filters, i.e. protection against corrosion, it is not recommended to use baking soda and caustic soda. They leave brown spots on the metal.

Step three. To dry the filters at room temperature in the case of dishwasher use it is not necessary .

Step Four. Putting the filters back in place. We insert the cassette into the box and press the lock.

Hoods

Don’t forget to run the timer

To avoid guessing the time or not the time, some devices are equipped with filter pollution indicators. The purpose of the display is to remind you in good time that a service is required.

There are two types of such “helpers”:

“Timers” or “time counters”. Their task is to measure the necessary time after which to start cleaning. Depending on the design, they can be limited to grease filters or can be built with both types of filters. This time is most often fixed, such as 2000 hours, and is determined by engineers based on average daily operation and air pollution saturation.

But in some models, this figure can be set by the user himself. After the set time has passed, the indicator light on the control panel lights up, so it’s time to start cleaning. Once the renewed filter is installed in place, a special button is pressed – a new countdown starts. This option is common to medium- and high-end hoods.

The symbols appearing or disappearing – these are indicators of saturation of only the grease filters, which, filled with grease particles, become visible or, conversely, merge with the main tone . They are used in cheaper models. If the indicators go off, it’s time for a “subbotnik”.

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John Techno

Greetings, everyone! I am John Techno, and my expedition in the realm of household appliances has been a thrilling adventure spanning over 30 years. What began as a curiosity about the mechanics of these everyday marvels transformed into a fulfilling career journey.

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Comments: 3
  1. Piper

    I found this article on hoods and their air-cleaning filters quite interesting. However, I am curious to know more about how these filters actually work. Are there different types of filters available for different types of air pollutants? How effective are they in removing harmful particles and pollutants? And are there any maintenance or replacement requirements for these filters?

    Reply
  2. Oakley

    This article provides a great overview of how hoods and filters clean the air. However, I’m curious to know if there are any specific types of filters used in hoods that are more effective at removing certain pollutants or particles? Are there any advancements or new technologies in air filtration systems for hoods?

    Reply
  3. Ethan Young

    Can you please explain how the filters in hoods effectively clean the air? I’m curious to understand the process and technology behind it.

    Reply
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