Siemens full range of siemens home appliances Choosing a hood Ducted or re-circulated operation?

How to choose a hood.

With open-plan living becoming more of the norm, a quiet and efficient extractor is necessary to deal with the strong cooking odours as well as the grease-laden air that can otherwise linger throughout the house. As far as style and design is concerned, with the Siemens range of cooker hoods, you’ll be spoilt for choice. But there are also two vital technical points to consider when choosing a hood. The first is whether you want the hood to be ducted or re-circulating, and the second is its power rating – and what you will require depends on your kitchen space. Here are some helpful pointers.

Choosing a hood: Ducted or re-circulated operation?

For optimum performance, your extractor hood should be ducted to the outside of the house, so that the extracted air is vented outside. But sometimes it is just not practical for the hood to be ducted to the outside, so most Siemens hoods can also operate in re-circulating mode (an additional carbon odour filter re-circulating kit is required to do this - please check individual product specifications for details of suitable accessories). In re-circulating mode, the extracted air is passed through the metal filter to remove grease, and then through a carbon filter to remove odours before being directed back into the kitchen. Although the extraction rate is slightly lower (when using this method) than ducted extraction and the odour filter will need to be replaced on a regular basis, recirculating the air offers an energy efficiency benefit, in that cool air is retained in the home in the summer, and does not vent out warm air during winter months.

Ducting your hood

For optimum performance, your extractor hood should be ducted to the outside of the house using ducting with as large a diameter as possible. The larger the ducting size, the greater the volume of air that can be extracted from the kitchen, and the quieter the hood will be. All Siemens hoods are now suitable for use with a 150mm diameter ducting, which increases efficiency and lowers noise levels even further, though 120mm ducting can still be used. Use of ducting with a lesser diameter should be avoided if possible. Ducting lengths should be as short and as direct as possible to ensure that the air is extracted to the outside as quickly as possible. Bends should be kept to a minimum and the ducting itself should be as smooth as possible to ensure smooth, unobstructed airflow.

Choosing a hood: the power to perform

Your chosen hood must be powerful enough to effectively remove moisture and cooking odours from your kitchen. As a rule of thumb, the hood should be able to change the air in the kitchen 10 times per hour. Here is a quick calculation you can make to check whether a hood is sufficiently powerful:

Firstly, calculate the volume of the kitchen

(H x W x D metres). Next, multiply that figure by 10. The resulting figure is the minimum extraction rate you require.

For example: Room: 4m x 4m x 2.5m = 40m3; 10 changes per hour = 10 x 40m3 = 400m3/h; so the hood must achieve a minimum of 400m3/h.

Minimizing noise

To keep noise to a minimum, we would suggest selecting a model that can comfortably meet the aforementioned requirements on an intermediate speed (e.g. level 2) rather than at the highest speed.

New wall mounting system

Once you’ve chosen which option you want to go for and you’re ready to install, we have made life even easier. Offset ‘cam’ rings mean that the fixings can be adjusted within a 6mm radius, making it simpler than ever to level the hood when fixing it.

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