Hello everyone,
We are currently building a new energy-efficient house and are considering whether to have a core drill hole installed for kitchen exhaust ventilation. Our chosen range hood can operate either as exhaust or recirculation. The project manager recommended using the hood in recirculation mode with activated carbon filters. However, the kitchen installer advises exhaust mode, as only this option supposedly eliminates odors and similar issues effectively.
We are now conflicted and thinking about having the core drill hole made but initially not using it, operating the hood in recirculation mode instead. The core drill hole would be fitted with an external grille cover and internally closed off with a cap. If needed later, we could connect the hood with a duct and have the setup ready for that.
From your point of view, is this a sensible approach, or am I missing something? What would you recommend? Should we have the core drill hole made or rather not?
Thanks in advance and best regards
We are currently building a new energy-efficient house and are considering whether to have a core drill hole installed for kitchen exhaust ventilation. Our chosen range hood can operate either as exhaust or recirculation. The project manager recommended using the hood in recirculation mode with activated carbon filters. However, the kitchen installer advises exhaust mode, as only this option supposedly eliminates odors and similar issues effectively.
We are now conflicted and thinking about having the core drill hole made but initially not using it, operating the hood in recirculation mode instead. The core drill hole would be fitted with an external grille cover and internally closed off with a cap. If needed later, we could connect the hood with a duct and have the setup ready for that.
From your point of view, is this a sensible approach, or am I missing something? What would you recommend? Should we have the core drill hole made or rather not?
Thanks in advance and best regards
B
Benutzer 30122 Mar 2026 07:28Since 2018, we have been using a "Berbel Wall Box BMK-F" with a diameter of 150 mm (6 inches) for our Berbel exhaust hood. It works perfectly. This wall box is also available for other manufacturers’ products.
Technical data:
For our new building with controlled mechanical ventilation, KfW40 standard, and a fireplace, it is very likely to have a Berbel recirculating hood or cooktop extractor with recirculation mode instead.
Technical data:
- Thermal insulation value of 0.95 W/m²K (equivalent to roughly triple-glazed insulating glass or 24 cm (9.5 inches) thick masonry with at least 6 cm (2.4 inches) of insulation)
- Blower door certification for use in low-energy buildings
- Suitable for installation on the wind-exposed side
For our new building with controlled mechanical ventilation, KfW40 standard, and a fireplace, it is very likely to have a Berbel recirculating hood or cooktop extractor with recirculation mode instead.
Is there a significant difference in terms of energy efficiency between a core drill hole of 130mm (5 inches) and 160mm (6.3 inches)? Or is the quality of the installed wall box more important? It might also be possible to reduce the exhaust duct from 150mm (6 inches) to 125mm (5 inches) and make a smaller core drill hole, but from what I have read, reducing the size is generally not recommended.
N
nordanney27 Mar 2026 13:04Haus2626 schrieb:
exhaust air combined with KfW40 should be possible without any problems. Yes and no. A ventilation concept must also be developed (mandatory). It must be ensured that the large amount of exhaust air can be adequately replaced. In winter, this means outside air at -10°C (14°F). This then leads to a different energy demand for the house and can cause the building to no longer meet the KfW 40 requirements.
Therefore, please put the term "without any problems" in big quotation marks.
We are currently planning to have the core drilling done for the exhaust vent. The top edge of our kitchen wall cabinets is at 219.8 cm (86.5 inches). The exhaust pipe is intended to run above the wall cabinets and connect to the wall box on the left side. The core drilling will have a diameter of 160 mm (6.3 inches). The drilling axis is planned to be positioned 20 cm (7.9 inches) below the ceiling underside. This means the drilling axis will be at 230 cm (90.6 inches), and the bottom edge of the drilling hole will be at 222 cm (87.4 inches), so it would be approximately 2 cm (0.8 inches) above the wall cabinets. Is this clearance sufficient to install a wall box (e.g. a Naber E-Jal flow) and connect the exhaust pipe?
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