ᐅ Sudden increase in HVAC system performance – all filters are clear
Created on: 8 Dec 2016 14:13
S
spyron
Hello everyone....
I am currently experiencing an issue with the built-in ventilation system in my Stiebel Eltro LWZ 404 SOL.
For the past two days, the system’s performance / airflow volume has increased noticeably, which has also resulted in a significantly louder noise level.
The power settings (level 2 during the day, level 1 during setback) and the associated configurations have not been changed. My first thought was that clogged filters might be causing the increase in performance, but I recently replaced all the filters and they still appeared clean upon inspection. This includes the filter behind the heat exchanger cassette.
When I went to check the filters, I noticed that even with the ventilation temporarily turned off, a lot of air was still being drawn in from outside and blown out. I had to turn the system off completely in order to inspect the filters without the fan running.
My assumption (as a complete layperson) was that the fan running despite the ventilation being off is probably used to supply the heating / hot water system with heat from the surrounding air. Since it is currently quite cold outside (around 0°C (32°F)) but the electric backup heater only activates when it reaches the bivalence point at -5°C (23°F), I can imagine that the ventilation unit has to work harder (i.e., exchange more air) than it would at above-freezing temperatures. In principle, this would be understandable. (Could someone please confirm whether this assumption is correct?)
What I don’t understand, however, is the increased performance of the central ventilation system. Normally, an increased airflow for heat recovery related to heating / hot water should not necessarily affect the ventilation system’s airflow / performance, or am I mistaken?
If these are unrelated, do you perhaps have any ideas what else could be causing the increased ventilation system performance? As I said, everything was running normally up until 2-3 days ago. Currently, we turn the ventilation completely off at night, even though the ventilation otherwise was not causing any issues.
I would really appreciate your help. Any hints or suggestions are very welcome.
Good luck, Florian
I am currently experiencing an issue with the built-in ventilation system in my Stiebel Eltro LWZ 404 SOL.
For the past two days, the system’s performance / airflow volume has increased noticeably, which has also resulted in a significantly louder noise level.
The power settings (level 2 during the day, level 1 during setback) and the associated configurations have not been changed. My first thought was that clogged filters might be causing the increase in performance, but I recently replaced all the filters and they still appeared clean upon inspection. This includes the filter behind the heat exchanger cassette.
When I went to check the filters, I noticed that even with the ventilation temporarily turned off, a lot of air was still being drawn in from outside and blown out. I had to turn the system off completely in order to inspect the filters without the fan running.
My assumption (as a complete layperson) was that the fan running despite the ventilation being off is probably used to supply the heating / hot water system with heat from the surrounding air. Since it is currently quite cold outside (around 0°C (32°F)) but the electric backup heater only activates when it reaches the bivalence point at -5°C (23°F), I can imagine that the ventilation unit has to work harder (i.e., exchange more air) than it would at above-freezing temperatures. In principle, this would be understandable. (Could someone please confirm whether this assumption is correct?)
What I don’t understand, however, is the increased performance of the central ventilation system. Normally, an increased airflow for heat recovery related to heating / hot water should not necessarily affect the ventilation system’s airflow / performance, or am I mistaken?
If these are unrelated, do you perhaps have any ideas what else could be causing the increased ventilation system performance? As I said, everything was running normally up until 2-3 days ago. Currently, we turn the ventilation completely off at night, even though the ventilation otherwise was not causing any issues.
I would really appreciate your help. Any hints or suggestions are very welcome.
Good luck, Florian
Unfortunately, it is currently dark both when I leave the house and when I return, so I will only be able to properly assess the current condition of our facade on the weekend. However, so far, nearly 18 months after the installation of the ventilation unit, I have not noticed any significant dirt buildup on the outdoor air intake. I will report back on the weekend with a detailed description...