ᐅ Tips and Tricks for Controlled Residential Ventilation Systems

Hello everyone,

Some of you may have already read my other thread about our building project.
https://www.hausbau-forum.de/threads/Projekt-Eigenheim-viele-fragen-wenig-Erfahrung.27222/page-6

Now, I would like to gather tips and knowledge from you all.
We plan to install a mechanical ventilation system with heat recovery.
According to the Helios mechanical ventilation easyPlan tool, we are recommended either a
mechanical ventilation EC 500W ET or
mechanical ventilation EC 370W ET unit.

Exhaust air volume is 236 m³/h (139 cfm) and
supply air volume is 234 m³/h (138 cfm).

Air exchange rate is 0.28.
Nominal ventilation is 235.
Intensive ventilation is 306.

We have an area of 280 m² (with basement and utility spaces) and
a volume of 849.95 m³ (30,000 ft³).

Which suitable devices can you recommend and why?
Is the duct length really 15 m (50 ft)? That could be problematic with my current planning.
We plan to use 75 mm (3 inch) round ducts.

Do you have any questions?

Thanks in advance for your insights and expertise.