The ventilation system is just a mild breeze

Hello here in the forum,

we have a controlled residential ventilation system with WR Nibe Ftx 230 W in use for one year in the energy-efficient house. Now a technician has determined that the ventilation values on the test protocol were falsified, as in my opinion no one really ever measured them, and the actual value supposedly always comes within +/- 1 % of the value.

The system runs at 100 %, but in all rooms only 4-5 m³/h arrives, which is far too little. In the basement only 1.8 m³/h. No control elements were installed and the system is sealed. The exhaust air in the kitchen, bathroom and toilet is sufficient.

The ventilation unit works perfectly, the air volumes are far too low. What could be the reason, what can be done?

Hello,

...Now a technician has determined that the ventilation values on the test protocol have been falsified, as in my opinion no one has ever really measured....

How do you come to this assessment?

...The system runs at 100%, but in all rooms only 4-5 m³/h arrives, far too little....In the basement only 1.8 m³/h.

Concrete volume flows, if no measurements were taken? Which values were planned?

...The ventilation unit works perfectly, the air volumes are far too low.

How does that fit together?

Kind regards.

Hello Euro,

thank you very much for your inquiries...

It was definitely not remeasured since, firstly, I lived 12 m away from the construction site and the technician claimed that it was calculated (supposed to be) and therefore the screed can be applied on it. The replacement technician never measured, he confirmed that and had to first familiarize himself with the device. The apparently determined values from 16 measuring points reach the actual value in one value and in 14 measuring points the value is about +1 or -1 %. That would already be a very, very big coincidence. Values for exhaust air were measured where there was no exhaust air, and the boiler room had no exhaust air at that time, this was only "installed" much later.

All planned values for the supply air are at 20 m3/h, parents 33 m3/h -

Now measured in the basement 1.8 m3/h, in the rooms 2.6-3.6 m3/h with the Nibe FTX 230 W running at max 100%.

The Nibe runs smoothly and I don’t think the speed can be increased any further. In the max range, however, the system is now too loud at the supply and exhaust air outside.

What impact would it have if, for example, a supply air duct was connected to the exhaust air?

Hello,

.... That would be a very, very big coincidence. Measurements were taken for exhaust air values where there was no exhaust air, and the heating room had no exhaust air at that time; this was only "installed" much later.

That is certainly an indication of a defect.

....All planned supply air values are at 20 m3/h, parents 33 m3/h -

Even that is somewhat strange, because in my planning such a thing usually does not occur. Who created the air volume plan according to DIN 1946-6?

....Now measured in the basement 1.8 m3/h, in the rooms 2.6-3.6 m3/h with the Nibe FTX 230 W running at max. 100%.

The pressure loss of the entire or parts of the system is too high and does not match the ventilation unit. Or vice versa. The actually planned operating point is not reached. A defect!

....The Nibe runs smoothly and I do not believe that the speed can be increased any further.

The design basis is the nominal ventilation. The other ventilation levels (volume flows) then result from this.

.... What would be the consequences if, for example, a supply air duct was connected to the exhaust air?

The entire concept gets confused! The room heating loads also change. Possibly, the heating no longer works efficiently as a result. Since overflow areas were presumably planned, odor problems can occur. The humid load removal is not guaranteed. An excessive exhaust air volume flow surplus arises. Additionally, mechanically induced infiltration... etc.

regards

So now I have checked the specified areas. The living room is actually not 42 m² but 55 m². A basement room is not 30 m² but 42 m². Then you calculated the exhaust air for 2 basement rooms, instead of the supply air as it actually is. The anteroom to the basement was designated as the only overflow room. For the hallway (ground floor) and corridor (upper floor), exhaust air was documented at 21 m³/h each – but the rooms do not have exhaust air and are (so I would now say) also "overflow" rooms. Of course, a tested value of 20 m³ was determined.

We built with a construction company – therefore the sanitary, heating, and ventilation company is not the direct contact. However, I find it somewhat fraudulent if such an air volume calculation is confirmed as a tested value. We paid for this service through the construction company as well...

How is it best to proceed now? Deficiency report with a 14-day deadline?

....We built with a construction company - therefore the sanitary, heating, and ventilation company is not the direct contact person. ...

Such results are not necessarily uncommon with the "all-inclusive" general contractor/general contractor projects.

.... We also paid for this service through the construction company...

That is usually the case. Unfortunately, contracts often provide poor leverage because clients are often too naive at the time of contract signing to pay attention to such details. Other things are usually more important. The significance of the technical building equipment (TGA) is recognized by very few in advance.

.... Deficiency notification with a deadline of 14 days?

A defect definitely has to be reported. How it is handled afterwards is usually a completely different story

Best regards