ᐅ Which mechanical ventilation system is compatible with a Viessmann heating system when applying for BAFA funding?

Hello dear forum community,

after signing the house construction contract with ARGE Haus Berlin, the next step is further planning.

ARGE Haus installs the Viessmann VITOCAL 200-G heating system with a 300-liter (79-gallon) buffer tank (brine heat pump). This is not changeable.

For mechanical ventilation with heat recovery, ARGE offers the PLUGGIT Avent P310 for an additional cost of about 16,000 EUR (including installation, 5-year warranty, etc.).

After reviewing the BAFA information sheet regarding the 35% subsidy for the heating system, I found that the Viessmann heating system and the Pluggit mechanical ventilation cannot interact with each other in terms of control systems (at least not directly). Therefore, it seems that a subsidy for the mechanical ventilation system is not possible. Or am I mistaken?

A different picture appears with the Viessmann Vitovent 300-F mechanical ventilation system. This can directly interact with the Viessmann heating system and is thus eligible for up to 35% subsidy.

In various other forums, I read that the Viessmann mechanical ventilation unit is somewhat louder and unfortunately also less reliable. Our ventilation system will be installed in the utility room on the ground floor (no basement).

On the other hand, I have read very positive things about the Zehnder Q350 mechanical ventilation system.

Ultimately, I have several questions that I cannot answer without your help:

1. What do you think of the Pluggit Avent P310, and is there a way to make it interact with the Viessmann heating system to qualify for the BAFA subsidy?
2. Is it possible to have the Zehnder Q350 interact with the Viessmann heating system?
3. The construction company advises against the Viessmann mechanical ventilation system, stating that although Viessmann produces very good heating systems, they are not specialized in ventilation systems. Do you agree?

As an additional note: we will not install a KNX system but plan to use Somfy. Could this enable linking the mechanical ventilation and heating systems in some way?

Thank you very much in advance for your help!
Matthias

I’m not quite sure what BAFA means by “interacting in terms of control systems.” I have the Vitovent 300-F, and for that model, the “interaction in terms of control systems” is limited to controlling it through the heating system control panel and the app. A mechanical ventilation system with a separate control panel doesn’t operate differently.

Regarding the Vitovent itself, it runs without problems here. When the filters are nearing the end of their life, it does get a bit louder, which I can hear through the utility room, but it’s not disruptive. The 300-F has a relatively low maximum airflow, so I would only recommend using it in “small” houses.

Quotation from the BAFA information sheet:

———————————
The operational control common to both concepts can be implemented using different approaches, including the following examples:

1. Wired or wireless connection; the devices share a common controller

2. Wired or wireless connection; the devices have separate controllers that are nevertheless interconnected for control purposes

3. Connection and control via the evaluation of a sensor

4. A higher-level control, for example through energy management, building automation, or “smart home” systems, along with the necessary bus systems
———————————

Regarding the volume flow: our house will have a size of 150 m² (1,615 sq ft) over two floors.

Hello Matthias,

Matthias_1212 schrieb:

2. Is there a way to have the Zehnder Q350 "interact" with the Viessmann heating system?

I am currently facing the same question. We were offered the Vitocal 222-S together with a Vitovent 300-F, but I would actually prefer a Zehnder Q350. Both manufacturers offer KNX integration, but the cost for this connection is already around 1000 EUR (which should also be eligible for funding). I haven’t found any alternatives. Even with KNX, there seem to be occasional rejections from BAFA, at least according to reports in HTD.

Since Zehnder advertises funding support among other things, I plan to contact their funding service again in the coming days. Maybe you have already done that?

Be careful with KNX integration. The Viessmann gateway is very limited and can only read data.
It’s better to control everything via an actuator.
With KNX, you can combine devices freely. That’s why I would also prefer to use Zehnder, Helios, or similar.

I spoke with Zehnder support. They said that, based on their experience, the solution using a timer and the utility company (EVU) contact of a heat pump is accepted by BAFA. They even sent a wiring diagram showing how to connect it. The timer costs around €80 (about $90), plus the Zehnder option box and the electrician’s fees. But if the electrician is already there (during new construction), they will likely do it for a small extra fee; it’s not rocket science.

Personally, I would prefer to implement a more flexible, custom solution (openHAB). This just needs to be approved by the electrician, since there must be some documentation or invoice confirming that the heat pump and the controlled residential ventilation system are operated together from a control perspective for BAFA to approve it. If no one can confirm such a setup without having implemented it themselves, then the timer solution will have to be used after all.