FAQ
TL;DR: For a 457 m3 home, keep supply/exhaust even, use gear 2 daily, and balance flows—“You do not regulate the flow by twisting the valves.” [Elektroda, Jan_Werbinski, post #16819771]
Why it matters: This FAQ helps DIY owners of VUT 350 PE EC set speeds, balance airflow, and stop condensate leaks without guesswork.
Quick Facts
- Daily use: gear 2 in mild weather; gear 1 in cold; gear 3 boost ~15 minutes. [Elektroda, Arbiter, post #16812938]
- Balanced ventilation target example: ~100 m3/h at ~30% fan, verified with a simple foil test. [Elektroda, Jan_Werbinski, post #16819771]
- Equal fan percentages ≠ balanced flows due to differing resistances. Balance by testing, not by menu symmetry. [Elektroda, Jan_Werbinski, post #16820686]
- Sizing: a larger unit can offer better motors and lower energy use, even if not strictly required. [Elektroda, Jan_Werbinski, post #16827030]
- Condensate management: some units must be installed with a slight slope; poor leveling causes leaks. [Elektroda, Jan_Werbinski, post #16841204]
What speed settings work best for everyday use?
Use the manufacturer’s equal supply/exhaust defaults. Run gear 2 for typical days, gear 1 in colder weather, and gear 3 as a 15‑minute boost when needed. This keeps comfort stable and noise low while ensuring adequate air changes. [Elektroda, Arbiter, post #16812938]
Should I leave 40/70/99% as the three speeds?
Yes. Those presets are safe and effective if supply and exhaust are set evenly. Adjust by season and occupancy: gear 2 most days, gear 1 in cold spells, and gear 3 for short boosts in kitchens or bathrooms. [Elektroda, Arbiter, post #16812938]
Do I balance air by twisting anemostats (diffuser ‘mushrooms’)?
No. Ductwork is designed for similar resistances; bends compensate for length. “You do not regulate the flow by twisting the valves.” Balance the system through fan control and verification, not diffuser throttling. [Elektroda, Jan_Werbinski, post #16819771]
How do I balance supply and exhaust without instruments?
Start with about 30% fan for ~100 m3/h. Set supply and exhaust to achieve neutral pressure. Verify with the foil test: in a tight house, a foil sheet in a doorway should hang still in calm weather. [Elektroda, Jan_Werbinski, post #16819771]
Quick How‑To: balance my VUT 350 PE EC today?
- Set both fans near 30% to target ~100 m3/h.
- Adjust supply/exhaust until a doorway foil hangs freely on a calm day.
- Save as gear 1; use higher gears for boost only. [Elektroda, Jan_Werbinski, post #16819771]
Are equal fan percentages the same as balanced airflow?
No. Equal percentages ignore different resistances on intake, supply, extract, and exhaust paths. Balance is the result of testing and adjustment, not mirrored settings. [Elektroda, Jan_Werbinski, post #16820686]
Is my VUT 350 PE EC undersized for a 457 m3 house?
Not necessarily. One user chose a larger unit for better motors and lower energy use, but sizing depends on target flow and pressure. If your unit meets airflow quietly at normal gears, it’s acceptable. [Elektroda, Jan_Werbinski, post #16827030]
What temperatures should I set on intake/supply sensors?
None. “The temperature is not set. You can read it.” Outdoor air follows weather, extract follows room temperature, and supply/exhaust depend on exchanger efficiency and flow balance. [Elektroda, Jan_Werbinski, post #16837009]
Why is speed 3 so noisy, and how should I use it?
High gear increases fan RPM and duct noise. Use it as a timed boost (about 15 minutes) for events like cooking or bathroom use. Keep everyday operation on gear 2 for comfort and lower noise. [Elektroda, Arbiter, post #16812938]
Why is water dripping even though the drain is connected?
Likely leaks or poor insulation creating thermal bridges. Condensate can escape joints or form on cold surfaces. The poster’s assessment: “Leaking and leaking. Or poor insulation... I bet on the former.” Inspect joints and insulation. [Elektroda, Jan_Werbinski, post #16839999]
How do I fix condensate pooling under the unit?
Ensure the unit is slightly sloped toward the drain. The OP solved leaks by re‑leveling so water flowed to the drain holes. Some recuperators require an intentional slope, not a perfectly horizontal mount. [Elektroda, marlowe27, post #16841073]
Installer left it level—should it be tilted from factory spec?
Yes, some models are installed with a slope. A flat install can send water to the wrong edge and cause leaks. Re‑set the level to direct condensate to the drain, per unit design. [Elektroda, Jan_Werbinski, post #16841204]
Can I copy the OP’s time‑of‑day schedule as a starting point?
You can. Example: 20% (~70 m3/h) from 08:00–16:00, 40% (~140 m3/h) from 16:00–22:00, 90% boost 22:00–23:30, then 40% overnight. Tweak for occupancy and air quality. [Elektroda, marlowe27, post #16820445]
Will open diffusers pull more air to the closest rooms?
Air favors lower‑resistance paths, but systems aim for similar branch resistances. Bends often compensate for length. Control with fan balancing, not diffuser throttling. [Elektroda, Jan_Werbinski, post #16819771]
Is using an anemometer at diffusers useful for setup?
Yes, for relative checks, but balance the whole system first. Use the foil neutrality test and fan percentages to set baseline, then fine‑tune rooms as needed. [Elektroda, Jan_Werbinski, post #16819771]
