Hello everyone,
We have been using a controlled residential ventilation system with a WR Nibe Ftx 230 W for one year in our energy-efficient house.
A technician recently found that the ventilation performance values on the test report appear to have been manipulated, as in my opinion no one has truly measured them, and the actual values are supposedly always within ±1% of the target.
The system runs at 100%, but the airflow in all rooms is only 4–5 m³/h (cubic meters per hour), which is far too low. In the basement, it is only 1.8 m³/h (cubic meters per hour). No control elements have been installed, and the system is airtight. The exhaust air in the kitchen, bathroom, and toilet is sufficient.
The ventilation unit works well, but the air volumes are much too low.
What could be the cause, and what can be done?
We have been using a controlled residential ventilation system with a WR Nibe Ftx 230 W for one year in our energy-efficient house.
A technician recently found that the ventilation performance values on the test report appear to have been manipulated, as in my opinion no one has truly measured them, and the actual values are supposedly always within ±1% of the target.
The system runs at 100%, but the airflow in all rooms is only 4–5 m³/h (cubic meters per hour), which is far too low. In the basement, it is only 1.8 m³/h (cubic meters per hour). No control elements have been installed, and the system is airtight. The exhaust air in the kitchen, bathroom, and toilet is sufficient.
The ventilation unit works well, but the air volumes are much too low.
What could be the cause, and what can be done?
Hello,
Best regards
Krolock schrieb:How did you come to this conclusion?
...Now the technician determined that the ventilation values on the test report were manipulated, because in my opinion nobody has really measured them....
Krolock schrieb:Concrete airflow rates if they were not measured? What values were planned?
...The system runs at 100%, but in all rooms only 4-5 m³/h (2.4-3.0 cfm) are delivered, which is far too little....In the basement only 1.8 m³/h (1.1 cfm).
Krolock schrieb:How does that fit together?
...The ventilation unit is working perfectly, but the air volumes are much too low.
Best regards
Hello Euro,
thank you very much for your questions...
There was definitely no measuring done because, firstly, I lived 12 m (39 feet) away from the construction site and the technician claimed that it was supposed to be calculated, and therefore the screed could be installed on it. The replacement technician never measured, as he confirmed, and had to get familiar with the device first. The apparently determined values from 16 measuring points show the actual value at one point and values within +1 or -1% at 14 measuring points. That would be an extremely unlikely coincidence. Values were measured for exhaust air where there was no exhaust air, and at that time the boiler room had no exhaust air either; this was only installed much later.
All planned values for supply air are 20 m3/h (706 cubic feet per hour), parents’ room 33 m3/h (1165 cubic feet per hour) –
now measured in the basement 1.8 m3/h (64 cubic feet per hour), and in the rooms 2.6–3.6 m3/h (92–127 cubic feet per hour) while the Nibe FTX 230 W is running at maximum 100%.
The Nibe runs smoothly and I don’t think the fan speed can be increased any further. At maximum output, however, the system is now too loud on both the supply and exhaust air outside.
What impact would it have, for example, if a supply air duct was connected to the exhaust air?
thank you very much for your questions...
There was definitely no measuring done because, firstly, I lived 12 m (39 feet) away from the construction site and the technician claimed that it was supposed to be calculated, and therefore the screed could be installed on it. The replacement technician never measured, as he confirmed, and had to get familiar with the device first. The apparently determined values from 16 measuring points show the actual value at one point and values within +1 or -1% at 14 measuring points. That would be an extremely unlikely coincidence. Values were measured for exhaust air where there was no exhaust air, and at that time the boiler room had no exhaust air either; this was only installed much later.
All planned values for supply air are 20 m3/h (706 cubic feet per hour), parents’ room 33 m3/h (1165 cubic feet per hour) –
now measured in the basement 1.8 m3/h (64 cubic feet per hour), and in the rooms 2.6–3.6 m3/h (92–127 cubic feet per hour) while the Nibe FTX 230 W is running at maximum 100%.
The Nibe runs smoothly and I don’t think the fan speed can be increased any further. At maximum output, however, the system is now too loud on both the supply and exhaust air outside.
What impact would it have, for example, if a supply air duct was connected to the exhaust air?
Hello,
Best regards.
Krolock schrieb:This is certainly an indication of a defect.
.... That would indeed be a very, very big coincidence. Measurements were taken for exhaust air where no exhaust air was present, and at that time the heating room did not have exhaust air; this was only "installed" much later.
Krolock schrieb:Even this is somewhat odd because in my planning such values usually do not occur. Who created the air volume plan according to DIN 1946-6 (the German standard for ventilation)?
....All planned values for supply air are at 20 m3/h (12 cfm), /h, parents 33 m3/h (19 cfm) -
Krolock schrieb:The pressure loss of the entire system or parts of it is too high and does not match the ventilation unit. Or vice versa. The intended operating point is not reached. This is a defect!
.... Now measured in the basement 1.8 m3/h (1 cfm), in the rooms 2.6-3.6 m3/h (2-2 cfm) while the Nibe FTX 230 W is running at a maximum of 100%.
Krolock schrieb:The design basis is the nominal ventilation rate. The other ventilation stages (airflow rates) are derived from this.
.... The Nibe runs smoothly and I don’t believe the speed can be increased any further.
Krolock schrieb:The entire concept falls apart! Heating loads in the rooms will also change. Possibly, the heating system will no longer operate efficiently. Since overflow areas were probably planned, odor problems may occur. Moisture load removal is not guaranteed. An excessive exhaust air volume flow surplus develops. Additionally, mechanically induced infiltration, etc.
.... What would be the consequences if, for example, a supply air duct was connected to the exhaust air?
Best regards.
So, I have now checked the specified areas. The living room is actually not 42 m² but 55 m² (470 sq ft), and a basement room is not 30 m² but 42 m² (452 sq ft). Then, for two basement rooms, they calculated the exhaust air instead of, as it actually is, the supply air. The anteroom was indicated as the only one with overflow air. In the hallway (ground floor) and corridor (upper floor), exhaust air was documented as 21 m³/h (12.4 cfm) each, although these rooms do not have exhaust air and are, as I would say, also "overflowing". Of course, a tested value of 20 m³/h (11.8 cfm) was determined.
We built with a construction company, so the sanitary, heating, and ventilation subcontractor is not the direct contact. However, I find it quite dishonest when such an air volume calculation is confirmed as a verified value. We also paid for this service through the construction company...
What is the best way to proceed now? Should I file a defect report with a 14-day deadline?
We built with a construction company, so the sanitary, heating, and ventilation subcontractor is not the direct contact. However, I find it quite dishonest when such an air volume calculation is confirmed as a verified value. We also paid for this service through the construction company...
What is the best way to proceed now? Should I file a defect report with a 14-day deadline?
Krolock schrieb:
.... We built with a construction company – therefore, the plumbing, heating, and ventilation subcontractors are not the direct point of contact. ... Such outcomes are not uncommon in turnkey general contractor (GC) projects. Krolock schrieb:
.... We also paid for these services through the construction company... That is usually the case. Unfortunately, contracts often provide little leverage because clients tend to be too naive at the time of signing to pay attention to such details. Other issues usually take priority. The importance of building services engineering is rarely recognized beforehand. Krolock schrieb:
.... Deficiency notice with a 14-day deadline? A defect should definitely be reported. How it is handled afterward is usually a completely different matter. Best regards.
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