ᐅ Controlled Residential Ventilation System – Decision Guide

Hello everyone,

We have decided to build with GÜ, and construction is about to start soon. Now we need to choose a specific mechanical ventilation with heat recovery system.

The single-family house has three floors (basement, ground floor, upper floor), and the floor area of each level is about 80 sqm (860 sq ft). The mechanical ventilation system is planned only for the ground and upper floors, not for the basement.

We are currently choosing between two systems: the Zehnder Comfoair Q350 and the Wolf CWL-300. The Wolf system would be 1,700 euros cheaper overall (including ductwork, installation, etc.).

From what I understand, the Comfoair Q350 is the newer system, has lower noise levels, and a higher heat recovery efficiency. Additionally, it is dimensioned for 50 m3 (1,765 cu ft) more airflow than the CWL-300, which might mean it could run at a lower fan setting during normal operation, making it quieter and more economical.

Our considerations now are: Do the lower measured noise levels actually make a noticeable difference in everyday use (or only under laboratory conditions)? Regarding the system sizing: In theory, 300 m3 (10,595 cu ft) max capacity would be sufficient for us, but would 350 m3 (12,366 cu ft) be better in practice? Ultimately, the Comfoair Q350 is probably the better system, but we wonder if the additional 1,700 euro cost is worth it for our house.

Which mechanical ventilation with heat recovery system would you recommend as experts? As non-professionals, it’s quite difficult for us to make the right choice.

Thanks in advance!

Also consider the price filter and whether, for example, there are options for cooling extensions.

I would go with the Wolf. I’m generally in favor of choosing a slightly larger size rather than too small, especially for the reasons you mentioned. But I wouldn’t increase by 1700 just for the 50 cubic meters.

Is the basement completely sealed off from the rest of the house, or why isn’t it ventilated?

baumhaus815 schrieb:
Hello everyone,

we have decided to build with GÜ and the start of construction is imminent. Now we need to choose a specific mechanical ventilation with heat recovery system.

The single-family house has three floors (basement, ground floor, upper floor), and the floor area of each level is approximately 80 sqm (860 sq ft). The mechanical ventilation system is planned only for the ground and upper floors, not for the basement.

We are currently choosing between two mechanical ventilation systems: the Zehnder Comfoair Q350 and the Wolf CWL-300. The Wolf system would be about 1,700 euros less expensive in total (including ductwork, installation, etc.).

From what I understand, the Comfoair 350 is the newer system, has lower noise levels, and a higher heat recovery efficiency. Additionally, it is designed for 50 m³/h (35 cfm) higher capacity than the CWL-300, which might mean it can operate at a lower setting during normal use, making it quieter and more cost-effective.

Our considerations are as follows: Will the lower measured noise levels actually be noticeable in real life, or only under laboratory conditions? How about the system size: theoretically, a maximum capacity of 300 m³/h (176 cfm) would be sufficient, but for practical reasons, wouldn’t the 350 m³/h (206 cfm) model be better? Ultimately, the Comfoair Q350 is probably the better system, but we are wondering if the 1,700 euro price difference is really worth it for our house...

As experts, which mechanical ventilation system would you recommend? As non-professionals, it’s quite difficult for us to make the right decision.

Thanks in advance!

We also have a basement, ground floor, and upper floor with 85 sqm (915 sq ft) and the Zehnder Q350. However, I don’t have any experience to share yet. I can’t comment on the other system. Have you already had detailed calculations and planning done?

Why is the basement not included? Is it unheated?

Mycraft: Ok, but what about the noise levels of the Wolf system? According to measurements, the Comfoair produces 39 dB(A) at 273 m³/h (160 CFM) exhaust air flow, while the Wolf already reaches 59 dB(A) at only 235 m³/h (138 CFM). I’m not sure if this difference is noticeable in real life, but the measured values are clearly quite different.

The basement is mostly utility space (except for an occasionally used office/guest room). We have also considered including the basement, but that would require a larger system capacity. The finished room is heated, the rest is not.

What do you think, what additional costs would be reasonable if we include the basement (84 m² (904 sq ft) floor area, including one finished living space) in the ventilation design?

What exactly is the difference between the equipment packages? The devices themselves are all quite similar in price. Usually, it’s the accessories that are more expensive.
I think the fans and silencers are probably of different quality.

The Zehnder should also be sufficient for your basement. It works fine for us.
The only question is about the wiring, pipes, and labor hours. However, we didn’t have an offer without the basement.