Nibe VVM 225 boiling sounds and knocking from Uponor floor heating
Hi there, I'm fairly new to Sweden, so apologies for not writing in Swedish. I tried to solve this problem by googling and asking the local serviceman, but I didn't really get anywhere. I guess you could point me in the right direction 
My setup is Nibe VVM 225 and Uponor Pro 1. I seem to have 2 problems that are probably connected:
1. Nibe VVM 225, when I consume a lot of hot water and water needs to be heated there is a boiling sound going on - and I guess it shouldn't happen. Maybe the reason is that we have too much iron and manganese in the well water, and thus we are adding air into water to combat the iron - most likely the air bubbles get into the system.
2. When Nibe heats the water and it is hot enough, it switches from water heating to floor heating. Exactly at that point I can hear knocking from the Uponor system. That is both worrying me and annoying, since it happens multiple times during the day and our bed is on the other side of the wall. I will note that this problem happens when it is cold outside - under minus 5.
See a video of both problems here: https://drive.google.com/file/d/19tpnu6W069DitVG39257CufkF30RlKZf/view?usp=sharing - I also added it to this post
What I have tried:
- I aired the Nibe VVM 225, both "water" and floor heating pipes - I had it running for 15-20 minutes - it didn't help
- I have set Nibe VVM 225 pressure to 1 - 1.5 - no difference. Before it was 0.3
- I asked Uponor support and they said I might need to air Nibe system (which I did). Also they said there is automatic air release system (red cap in the video) in the Uponor system, so the air should go out anyway - so no solution
- Nibe support didn't help
- Local contractors - I got a mixed number of replies - saying it is normal, or they haven't seen it before. Nobody wanted to come over and fix it.
So here I am, kinda lost asking for help. Do you have any clue what to do? Is it okay, or shall I worry about it now?
The house was built in 2019 and I'm the second owner. I'm not sure if there was a service done on the system before. The problem started in September/October 2023, when it got colder outside.
Many thanks
My setup is Nibe VVM 225 and Uponor Pro 1. I seem to have 2 problems that are probably connected:
1. Nibe VVM 225, when I consume a lot of hot water and water needs to be heated there is a boiling sound going on - and I guess it shouldn't happen. Maybe the reason is that we have too much iron and manganese in the well water, and thus we are adding air into water to combat the iron - most likely the air bubbles get into the system.
2. When Nibe heats the water and it is hot enough, it switches from water heating to floor heating. Exactly at that point I can hear knocking from the Uponor system. That is both worrying me and annoying, since it happens multiple times during the day and our bed is on the other side of the wall. I will note that this problem happens when it is cold outside - under minus 5.
See a video of both problems here: https://drive.google.com/file/d/19tpnu6W069DitVG39257CufkF30RlKZf/view?usp=sharing - I also added it to this post
What I have tried:
- I aired the Nibe VVM 225, both "water" and floor heating pipes - I had it running for 15-20 minutes - it didn't help
- I have set Nibe VVM 225 pressure to 1 - 1.5 - no difference. Before it was 0.3
- I asked Uponor support and they said I might need to air Nibe system (which I did). Also they said there is automatic air release system (red cap in the video) in the Uponor system, so the air should go out anyway - so no solution
- Nibe support didn't help
- Local contractors - I got a mixed number of replies - saying it is normal, or they haven't seen it before. Nobody wanted to come over and fix it.
So here I am, kinda lost asking for help. Do you have any clue what to do? Is it okay, or shall I worry about it now?
The house was built in 2019 and I'm the second owner. I'm not sure if there was a service done on the system before. The problem started in September/October 2023, when it got colder outside.
Many thanks
The tapping sound can come from hot water rushing out in the heating system, after making hot water, and then changing back to normal heating. The boiling sound when making hot water can be normal, i had hard time hear it, but when the electric heater starts, it can appear som boiling sounds, there can also be air in system. To air it, fill to 1,5 bar, shut the heater down, wait 10 minutes, and release water/air from the system at least 20 seconds from each tap.