Hello everyone,
to all controlled residential ventilation system owners: Have you ever measured the CO₂ levels in ppm in your ventilated rooms out of curiosity?
According to information online, the values should be below 1000 ppm. About 400 ppm is the fresh outdoor air level. Normally, I have around 600 ppm – 700 ppm when no one is in the room. Of course, this value increases with the number of people present.
What I’ve noticed is that in our bedroom, the level rises above 1000 ppm during the night, which is not ideal. I originally thought that was exactly why I installed a controlled residential ventilation system – to always have fresh air.
So, I would be interested in comparison values from you, if you have any.
Maybe something is wrong with the system.
to all controlled residential ventilation system owners: Have you ever measured the CO₂ levels in ppm in your ventilated rooms out of curiosity?
According to information online, the values should be below 1000 ppm. About 400 ppm is the fresh outdoor air level. Normally, I have around 600 ppm – 700 ppm when no one is in the room. Of course, this value increases with the number of people present.
What I’ve noticed is that in our bedroom, the level rises above 1000 ppm during the night, which is not ideal. I originally thought that was exactly why I installed a controlled residential ventilation system – to always have fresh air.
So, I would be interested in comparison values from you, if you have any.
Maybe something is wrong with the system.
C
chand198621 Sep 2017 17:54Hello,
where exactly are you measuring the CO2 levels?
A possible cause could also be that, due to the room geometry, zones develop with little circulation despite the continuous operation of the mechanical ventilation system. In such areas, CO2 could accumulate over a longer period of time. If you are measuring precisely there…
Admittedly, this is not very likely, but 1000 ppm CO2 despite air exchange with the outside seems a bit high to me as well.
where exactly are you measuring the CO2 levels?
A possible cause could also be that, due to the room geometry, zones develop with little circulation despite the continuous operation of the mechanical ventilation system. In such areas, CO2 could accumulate over a longer period of time. If you are measuring precisely there…
Admittedly, this is not very likely, but 1000 ppm CO2 despite air exchange with the outside seems a bit high to me as well.
Sorry for the late reply.
I have calculated the house volume of the ventilated rooms. Should I only consider the rooms with supply air or also the exhaust air rooms?
In total, it is 485 m³ (17,130 cubic feet) for all rooms including supply and exhaust air rooms. If I exclude the exhaust air rooms, I get 300 m³ (10,590 cubic feet).
Our mechanical ventilation system Vallox 350 delivers 350 m³/h (12,360 cubic feet per hour). It is running at about 70% of its capacity, which can also be heard in the utility room.
Could it be possible that the mechanical ventilation system is too small for our house? It seems strange to me that the system is set so high and the ventilation quality is still not satisfactory.
I look forward to your feedback.
I have calculated the house volume of the ventilated rooms. Should I only consider the rooms with supply air or also the exhaust air rooms?
In total, it is 485 m³ (17,130 cubic feet) for all rooms including supply and exhaust air rooms. If I exclude the exhaust air rooms, I get 300 m³ (10,590 cubic feet).
Our mechanical ventilation system Vallox 350 delivers 350 m³/h (12,360 cubic feet per hour). It is running at about 70% of its capacity, which can also be heard in the utility room.
Could it be possible that the mechanical ventilation system is too small for our house? It seems strange to me that the system is set so high and the ventilation quality is still not satisfactory.
I look forward to your feedback.
B
Bieber08154 Oct 2017 22:49Tommes78 schrieb:
I calculated the house volume of the ventilated rooms. Should I only consider the rooms with supply air or also the exhaust rooms? The total volume is what matters. Usually, the calculation is based on 0.5 air changes per hour. In your case, that means a volumetric flow of 240 m³/h (141 cfm). 70% of 350 m³/h (206 cfm) is exactly 245 m³/h (144 cfm), which corresponds to an air exchange rate of 0.5 per hour. That sounds good.
How many people are there in the household? Can you "calibrate" your measuring device outdoors (i.e., take a measurement)? Have you tried using the CO2 calculator from Lower Saxony?
Just a quick question: when the ventilation is designed for the total volume, does the total volume refer to the cubic measurement of the house? In our case, that would be 789 m³ (27,854 ft³). With an air exchange rate of 0.5, we'd still have almost 400 m³ (14,130 ft³). Which ventilation system is supposed to handle that?
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