ᐅ Controlled residential ventilation & heat pumps: Viessmann vs. Vaillant vs. Zehnder?

Hello everyone,

I want to revisit a topic that was mentioned a while ago in another thread but deserves a more detailed discussion, as it turns out to be more complicated than anticipated. Here’s our situation, and I would really appreciate hearing about your experiences. Starting with the background.

We are currently building a prefabricated house (timber construction) with a prefab home manufacturer. The plot is located in a small village, in a very old part of town. It seems like almost everyone heats with wood there. On our property, there is a wood smoke smell throughout the entire winter (we noticed this last year already, and it’s happening again this year), as if there is a campfire burning nearby non-stop.

Now, we are seriously concerned that with a mechanical ventilation system with heat recovery (MVHR), the indoor air could end up smelling the same as the outdoor air, which we definitely want to avoid. To counter this, we thought about installing a mechanical ventilation system with an activated carbon filter included. That’s why we have tentatively selected the Zehnder ComfoAir Q350 TR in the enthalpy version, since both of us already occasionally suffer from dry eyes. This system also comes from the factory with attachments for activated carbon filters.

Unfortunately, things turned out differently than expected. The house supplier is hesitant in initial discussions and is postponing the topic until the customization meeting in December. The reason given: they only work with Viessmann or Vaillant because the heat pumps come from those manufacturers. More precisely, it would be either the Viessmann Vitovent 300W or the Vaillant recoVair VAR360 ventilation system. Neither of these original systems offers a solution with an activated carbon filter.

Now to my main question. What’s your opinion on this? Our concern is not unfounded, and an F7 pollen filter doesn’t seem to be an adequate solution for this situation, does it? They immediately said that an F7 filter would be sufficient, but we don’t believe that.

Is it possible to install a Zehnder mechanical ventilation system alongside a heat pump from Viessmann or Vaillant, or not?

I don’t want to assume the worst-case scenario, but do you have any ideas on how to solve this problem if the house provider doesn’t allow any other mechanical ventilation system?

I would be very grateful for any ideas, experiences, or tips!

Best regards

There are replacement filters with activated carbon available for the recovair. I cannot tell you how well they work in practice.

Nixwill2 schrieb:

You can install a Zehnder controlled ventilation system alongside a heat pump from Viessmann or Vaillant, right?

Yes, absolutely.

Nixwill2 schrieb:

Our concern isn't unfounded, and an F7 pollen filter isn't a solution for this, is it?

No, an F7 filter does not block odors.

I would simply look for suitable replacement filters with activated carbon.

Tolentino schrieb:

There are replacement filters with activated carbon available for the Recovair. However, I can’t say how well they actually perform in practice.

That’s exactly what we want to avoid. I’ve already found activated carbon filters online for both Viessmann and Vaillant. However, I’m very cautious about these because I have no idea where they come from or how contaminated they might be. Furthermore, you can’t always rely on their availability, and they might eventually become unobtainable.
That’s why we wanted to go with a manufacturer who can supply the whole system using original accessories, and I think Zehnder is trustworthy in this respect, especially regarding ongoing availability...

@Mycraft
This response also fits your statement.

Where do you think Zehnder gets their filters from? They are probably made in the same factory by the same workers, once with the brand name and once without.

They have to comply with RoHS and REACH anyway. Otherwise, customs would block them.
As long as the OEMs sell them, others will sell them too.

By the way, a bit of feedback regarding standard F7 filters:
Get rid of any that don’t perform well in heating the area, but not as badly as you say. However, I haven’t noticed any smell in the house. That doesn’t necessarily mean anything...

Tolentino schrieb:

As long as the OEMs sell it, someone else will sell it too.

What do you mean by that? There must be some reason why Viessmann and Vaillant don’t just sell it themselves at double the price, right?

With Zehnder, it’s a complete additional filter housing (ComfoWell 320), which I believe is effectively "on top" of the standard filters.

Do you see any way to retrofit such a housing (like the one from Zehnder) to the Viessmann or Vaillant systems? I have no idea how that would work, but I guess it might just involve inserting it in between somehow...

Is there a significant difference between these three manufacturers that could still be mentioned during the material selection process? A while ago, I read a very long and ongoing thread in another forum that has lasted for years until now. It claimed that the Zehnder controlled residential ventilation system with enthalpy exchanger allegedly smells like plastic. There are said to be issues with Vaillant related to some flaps not opening (or closing) as expected when the temperature conditions would logically require it. For Viessmann, there was also something, but I’ve already forgotten what exactly.

I’m just asking for keywords or pointers that I can research myself later. If you know anything about this, please share.