Controlled Residential Ventilation & Heat Pump: Viessmann vs. Vaillant vs. Zehnder?

2022-11-27 10:33:41

For the quantities, the 300 units would be sufficient for the EG/OG. Although in my opinion, it is somewhat tight. If the basement rooms are to be included (which is recommended, after all, it is a shell), one should go one step higher and choose a system with a maximum of 400 cbm or even 500. So that it does not constantly operate in the upper load range.

2022-11-27 18:42:20

Thank you both!!!

Unfortunately, I mistakenly entered the volume of the upper floor twice in the total figures, but on the ground floor it is not 166.89m3, but 226.36m3. , that means your assumed 407m3 increases to 467m3. That naturally increases everything a bit more. And if we now follow the recommendation of and also include the other basement rooms, then we would have even 115.67m3 more, so actually 583m3 :oops:.

I'm starting to get worried that our budget will be blown here as well, because the datasheet of the Viessmann Vitovent 300-W states that 400m3 is the limit; that's their largest system!

What is very strange, however, is that the datasheet includes the following statements:
- H32S A225 max. volume flow 225m3/h for residential units up to 160m2 living space
- H32S C325 max. volume flow 325m3/h for residential units up to 320m2 living space
- H32S C400 max. volume flow 400m3/h for residential units up to 440m2 living space

I don’t quite understand that, our house is certainly not the largest; if I add up all the square meters, including usable areas, I get about 235m2. How can Viessmann specify a volume flow of 400m3 for 440m2 and we actually calculate more than 500m3 for our "little house"?
It's also strange that the alternative unit from Vaillant (recoVAIR VAR 360/4) also manages a maximum of 360m3/h and they say here up to 290m2 living space o_O?

I’m about ready to have the basement completely removed from the planning because everything else would simply blow our budget even more... :(

2022-11-27 19:00:59

The number of flap valves is basically determined by the number of rooms. Living and common rooms receive supply air. Bathrooms, kitchen, and utility rooms receive exhaust air.

That is indeed very interesting; I wasn't aware that not every room receives both supply and exhaust air! So, does that mean the living room only gets supply air and the exhaust air for that could be located in the kitchen? Then the next supply air is in the guest room and the corresponding exhaust air only again in the guest bathroom? Is that how it should be understood when looking at one floor? Is that possible even through closed room doors?

2022-11-27 19:42:51

Thank you both very much!!!

Unfortunately, I mistakenly indicated the volume of the upper floor twice in the total figures, but in the ground floor it is 226.36m3 instead of 166.89m3. , that means your assumed 407m3 increases to 467m3. That naturally increases everything a bit more. And if we now also follow the recommendation of and should include the other basement rooms, then we would even have another 115.67m3 more, so actually 583m3 :oops:.

I'm starting to get scared that the belt will be burst here again, because the data sheet of the Viessmann Vitovent 300-W states that 400m3 is the limit, that's their largest system!

What is however very strange is that the data sheet contains the following statements:
- H32S A225 max. volume flow 225m3/h for residential units up to 160m2 living space
- H32S C325 max. volume flow 325m3/h for residential units up to 320m2 living space
- H32S C400 max. volume flow 400m3/h for residential units up to 440m2 living space

I don't quite understand that, our house is certainly not the largest, if I add up all the square meters, including utility areas, I come to about 235m2. How can Viessmann specify a volume flow of 400m3 at 440m2 and we actually calculate more than 500m3 for our "little house"?
It's also strange that the alternative device from Vaillant (recoVAIR VAR 360/4) also manages a maximum of 360m3/h and they also say here up to 290m2 living space o_O?

I'm just about to have the basement completely removed from the planning because everything else simply blows our budget even more... :(

That is because many manufacturers calculate a nominal ventilation with 0.5 times the air volume and 2.5m room height. As you can see from their data, it fits quite well
290m² * 2.5m = 725m³ * 0.5 = 362.5m³/h.
Personally, I had my ventilation set to 0.7 times air exchange in the first 2 years to get rid of moisture. For 4 years now, I have had a daytime air exchange of 0.3 times and when everyone is home (4 people) an air exchange of 0.4 times. We have never had mold and didn’t even use the windows specially for ventilation. Due to the F7 filter in the supply air, with the 500m³ controlled residential ventilation, I can only achieve a maximum of 0.7 times air exchange in the supply air. Exhaust would manage about 0.85.

That is very interesting though, I was not aware that not every room actually gets supply and exhaust air! Does that mean only supply air comes into the living room and the exhaust air for that could be located in the kitchen? Then the next supply air in the guest room and the corresponding exhaust air only again in the guest bathroom? Is that how it’s to be understood when looking at a single floor? Does it also work through room doors that are closed?

No, otherwise you wouldn’t have good room airflow. The disc valves should be as far away as possible from the room door and the hallway is used as an exhaust air duct and e.g. the bathroom is used for extraction.
You can also adjust the exhaust disc valves so that, for example, only part is extracted in the basement and the rest is drawn to the ground floor and discharged there.

Room doors can be closed if you don’t have airtight doors. A gap of 0.5 - 1 cm between the floor and the door leaf is enough.

2022-11-28 16:43:40

I actually don't really know what to do now. The two systems that the house provider has in the program seem to be too small for the whole house. They don't allow another system (we will only see this for sure next week --> appointment with them), which can only mean that I would have to leave out the basement...

I don't understand that, I don't consider our house to be that big, can it really be that the ~150m2 is the maximum for these two manufacturers...

What would you recommend to me? Leave out the basement, so no ventilation in the basement?

2022-11-28 21:32:39

I’m not really sure what I should do now. The two systems the house provider has in the program seem too small for the whole house. They don’t allow another system (we will only see that definitively next week --> appointment with them), which can only mean that I would have to leave out the basement...

I don’t understand this, I don’t consider our house that big, could it really be that the ~150m2 is the maximum for these two manufacturers...

What would you recommend? Leave out the basement, so no ventilation in the basement?

What they allow is initially secondary, since you are the one with the money. It’s more about the commissioning, which is always done differently by the manufacturers but is basically the same. I wouldn’t leave out the basement if you’re building new anyway. You can’t hide the ventilation ducts better than now. What would they waive if you provide the controlled residential ventilation yourself?

P.S. Our house is also only 140m² + warm roof with 40m² area and our Helios controlled residential ventilation is a 500, which runs depending on the time of day at about 50% or 70%.

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Controlled Residential Ventilation & Heat Pump: Viessmann vs. Vaillant vs. Zehnder?

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