Kitchen funnels are used to extract hot air, saturated with moisture, vapor and odors, where the extracted amount needs to be replaced with fresh, if necessary pre-heated air. There are two types of funnels: the regular funnel and the eco-funnel. The difference lies in the fact that the eco-funnel in comparison to the usual one injects 70% of the outside non-heated air which is brought in by means of a special ventilator and canal so that it is inserted with high speed into the extraction filters inside the very funnel by means of an adjustable opening of the nozzle profile.
When it comes to kitchen ventilation, what we are dealing with is hot air, saturated with moisture, vapor, and odors, where the extracted amount needs to be replaced with fresh, if necessary, preheated air. Kitchen ventilation most often requires the extraction of a large amount of contaminated air, which also means a great number of air changes, which may cause a draft. Considering the fact that the pre-heating of the injected fresh air in the colder months of the year is still necessary, it in fact represents a great loss of heat energy, since the minimal temperature of the injected air must be 20˚ C.
Basically, there are two types of funnels:
- The regular (conventional) extraction funnel
- The economic extraction funnel (eco-funnel)
The main funnel parts:
- The body of the funnel (the housing) which can be made from stainless steel or Al sheet metal
- Filters for grease extraction made from multi-layered stretched Al sheet metal or flame retardant filters used to separate grease, made from stainless steel sheet metal, or combined filters used to separate the grease.
- Canal connectors for the extraction and injection of air at the top of the funnel.
- Regulation blinds used to adjust the air flow (ARA built into the canal connectors, delivered on demand).
- Elements used to hang the funnel:
chains and tensile hooks for fine leveling (they are delivered with the funnel).
The size of the funnel is determined according to the size of the kitchen appliance from which the polluted air will be extracted. If for example there is a stove with ovens below the funnel, then the dimensions of the funnel are determined according to a base which includes the stove and all of the ovens when open.
Regular (conventional) extraction funnel
This funnel is used to extract vapors, fumes and odors in hotels and restaurants and also industrial facilities. Generally speaking, in order to achieve the proper functioning of the extraction section of the funnel, it is necessary to extract relatively large amounts of air, especially because the dimensions of the funnel must be greater than the dimensions of the work surface from which the polluted air is being extracted. For this reason, when determining the amount of air and the encompassed extraction speed, we need to take into account the intensity of the cross-section flow of vapor, gasses or smoke above the work surface. The closer the funnel is to the work surface from which the vapor or smoke is being extracted, the more efficient it will be more. At the same time we need to bear in mind the free height necessary for the movement and work of the staff working below the funnel, especially in the case of kitchen funnels.
It is not enough to just extract the air polluted with vapor, smoke and odors, it is also necessary to forcefully inject fresh air as well (which in winter is warmed to 20˚ C) in order to prevent any cold air drafts coming through the windows or doors.
Economical extraction funnel (eco-funnel)
Just like the regular one, the economical funnel is used to extract gasses, vapor, smoke and odors in kitchens, hotels and restaurants and in industry facilities. The Eco-funnel, when compared to the regular one, works with approximately 70 % of the outside air, which is brought in by means of a special ventilator and canal so that it is inserted with high speed into the extraction filters inside the very funnel by means of an adjustable opening of the nozzle profile. The great speed of the cross-section cold air flow leads to the induction of a low air pressure zone directly below the funnel, which leads to the effective extraction of the vapors, smoke, grease particles and odors. The cold air flow also reduces the filter temperatures below the condensation temperature of grease (40˚C) which increases the elimination of grease and steam. As a result of this, there is less grease residue in the extraction system, it is easier to clean and maintain, there is a reduced risk of fire and better protection of the façade and roof of the building. Nevertheless, in order for this type of funnel to work properly, it is necessary to replace approximately 30 % of the extracted air in the kitchen with fresh air, in the winter preheated to 20˚C. A significant advantage of the eco-funnel when compared to the regular one is the significantly lower temperature of the extracted air (40 ÷ 50˚C).