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2018-11-06

Hood check valve - see why it's important

Non-return valve for the cooker hood – find out why it’s important


Non-return valve for the cooker hood prevents air from outside entering the kitchen. See how to install it correctly.

Why do we need a kitchen hood?


Kitchen hoods are now an essential piece of equipment in every modern kitchen where cleanliness and safety are a priority. Their main function is air purification from steam, harmful substances from cooking and frying, as well as removing unpleasant odours, grease particles, dust, and other allergens.

By removing moisture from the air, they protect furniture, other kitchen appliances, and walls from grease build-up. As a result, our home stays cleaner and requires less frequent renovations.

Kitchen hoods are also an additional light source. Often, this is energy-saving LED lighting, which consumes much less power than older halogen bulbs.

Another advantage of kitchen hoods is their decorative function – some models are truly stylish additions to our home.

Two ways to connect a kitchen hood


Kitchen hoods can operate in two modes: extraction and recirculation. Let’s briefly discuss the differences between these options.

Hood in extraction mode

Hoods in extraction mode operate in an open system. This means they are connected to a separate ventilation duct (chimney) via an appropriate pipe (round or rectangular). The water vapour and other air impurities are then vented outside (directly outside in a detached house or into a central ventilation duct in apartment blocks).

Extraction mode operates with a metal filter (usually aluminium), which should be cleaned regularly (about once a month). To maximise the hood’s efficiency, consider installing a plasma filter, which is permanent and offers enhanced effectiveness in removing and neutralising unwanted substances from the air.

Hood in recirculation mode

A hood in recirculation mode operates in a closed system, meaning the purified air is returned to the kitchen. This type of hood requires an additional carbon filter to neutralise unpleasant odours and absorb water vapour. The carbon filter should be replaced every 3–6 months to maintain efficiency, unless your hood is equipped with a Long Life carbon filter, which lasts for several years.

The non-return valve for the hood is used only in the first case, where the hood operates in extraction mode.

Types of non-return valves for cooker hoods


The role of a non-return valve in a hood is to prevent outside air from entering the kitchen. There are several types of non-return valves.

Non-return valve flap installed at the hood outlet – this is the most common solution, included with most hoods, and is also the most recommended.

 

non-return valve flap globalo

 

Non-return valve flap installed at the hood motor outlet


Collar with flap installed near the wall.

 

collar with flap

 

Round duct connector with collar


Recommended ducts are round pipes, as they offer minimal air resistance and are suitable for very long ventilation systems. The model shown above is part of the EASIPIPE system, made of non-flammable plastic that meets international building standards, resists corrosion, and is durable against changing weather conditions and UV exposure. It will not deform or discolour.

Connector with non-return valve flap – available as a round or rectangular connector.

 

non-return valve for hood

 

Round duct connector 10 cm


This connector enables the serial connection of round ducts while preventing air backflow via the non-return valve. The model shown above is made of non-flammable and corrosion-resistant PVC, with a diameter of 10 cm (fi 10 cm). The connector allows for connecting ducts with a diameter of 10 cm without the need for additional joints.

Another type of non-return valve connector for the hood is the flat duct connector.

 

 

flat duct connector

 

Flat duct connector with non-return valve


The 20.4x6 cm flat duct connector with a non-return valve is part of the SUPERTUBA system. It’s used in systems where medium or high air flow is required. Flat ducts are commonly used in ceiling or countertop hoods.

Purpose of the cooker hood’s non-return valve


The non-return valve is installed in homes to prevent outdoor air from re-entering, and in multi-storey buildings, to prevent odours and moisture from the central ventilation duct from entering the kitchen.

Imagine living in a multi-storey building where hoods lack non-return valves. This would allow unwanted odours from other apartments to enter our kitchen. Surely, everyone would want to avoid such a situation.

Similarly, without a non-return valve in a detached house, the exhausted, contaminated air would flow back into the kitchen, also bringing in outside air, which is often heavily polluted (exhaust fumes, smog). Additionally, in winter, cold air would enter the kitchen, causing it to cool down.
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