Apartment ventilation — 5 common mistakes and how to avoid them

Apartment ventilation seems simple at first glance — two ducts, one in the kitchen, one in the bathroom. In reality, every year we see hundreds of apartments where small decisions have caused big problems: mold on the walls, bad odors from the neighbor's apartment, a perpetually foggy mirror. Let's look at the 5 most common mistakes.

Mistake 1 — Connecting the kitchen hood to the general ventilation duct

A classic renovation mistake: the old kitchen grate is removed, and an active (motorized) hood is connected in its place. Result: the hood pushes kitchen odors into the neighbor's apartment through the same duct, from top to bottom.

Solution: The kitchen hood must operate through a backdraft damper and ideally into a separate exhaust duct (if available) or with recirculation (charcoal filter). For large hoods (over 400 m³/h), active connection to the general duct is prohibited in apartment buildings.

Mistake 2 — Taping up the ventilation grate

"After washing, clothes stay wet for a long time" → someone suggests taping up the duct. This is a guarantee of mold — moisture gets trapped in the bathroom, condenses on the wall, and starts the mold cycle.

Solution: If the duct "pulls in reverse", the problem is in the apartment building's common duct (for example, the apartment above has blocked it). The solution is an active exhaust fan in the bathroom and micro-ventilation in the window or a fresh air vent in the wall for the room.

Mistake 3 — Completely sealed PVC windows without air intake

Old wooden windows let a little air through. New PVC windows are airtight. If no fresh air intake solution has been installed in the apartment, moisture will start to condense on the windows, and mold may form on the walls.

Solution: Install a wall vent (e.g., Aereco EHA²) on the exterior wall of the living room and bedroom, or window micro-ventilation. A heat recovery solution (single unit — Vallox 51 MV or similar) is more expensive but conserves energy.

Mistake 4 — Lack of ventilation for washing machine or dryer

A condensation dryer or washing machine releases moist air directly into the bathroom. If the exhaust cannot remove it, moisture accumulates inside the walls.

Solution: A humidity-sensor fan in the bathroom that turns on when the humidity level rises to 65%. Even better — an exhaust dryer with a separate duct system.

Mistake 5 — Incorrect installation of a central ventilation unit in the apartment

A compact heat recovery unit is purchased and installed, but the ducts are too narrow (Ø 75 is sometimes used instead of Ø 125). Result — noise, fans consume 3× more energy, and airflow volumes remain below standard.

Solution: Order a ventilation design project that calculates duct diameters and airflow volumes. Typical dimensions in apartments are Ø 125 (main ducts) and Ø 75 branches. A good choice is the Komfovent Domekt R 200, installed in the ceiling.

Bonus mistake — Lack of maintenance

All of the above loses its meaning if filters are not changed twice a year and the device is not cleaned once a year. With an annual maintenance package (starting from 79 €/year), you keep the device in top working condition and the warranty valid. See also ventilation cleaning recommendations.

How to assess the situation of your apartment?

1. Place a piece of paper against the bathroom duct — if it doesn't stick, the draw is weak.
2. Look at the windows in the morning — if there is water on the glass, the humidity is over 60%.
3. Check wall corners — dark spots are the beginning of mold.
4. In the kitchen: after cooking, the smell should disappear within 30 minutes.

Summary

Apartment ventilation does not have to be expensive or complicated, but it must be well thought out. Avoid typical mistakes, check air exchange, and if necessary, call a specialist.

Would you like a ventilation audit or a new system for your apartment? Explore apartment ventilation solutions or contact us for a free consultation.