ᐅ Rhythmic clicking noise in the manifold of the underfloor heating system

Hello everyone,

I have already done a lot of research on clicking noises in heating systems but haven’t found any clear information about what might be causing it in our case.
We built a new house 3 years ago (2 stories). Our heating system is a water-to-air heat pump from Vaillant with underfloor heating.
From the heating circuit manifold on the upper floor, there is a rhythmic clicking noise:

• It only occurs during the heating season
• The colder it is outside, the louder and more frequent it seems to be
• It is not tied to a specific time of day
• When all actuators are set to “manual,” we cannot observe the clicking
• The clicking is mostly rhythmic and consecutive, but sometimes occurs sporadically
• The clicking does not seem to be related to the room thermostats – adjusting the temperature did not trigger the noise

What has already been tried:

• Checked that the supply and return lines at the heating circuit manifold are not reversed
• Checked that the supply and return lines on the bathroom towel radiator are not reversed
• Replaced all actuators on the heating circuit manifold on the upper floor
• Replaced the heating circuit manifold on the upper floor

I wanted to upload a recording, but mp3 and mp4 formats were unfortunately not accepted. If needed, I can send the recording directly upon request.

The plumbing company and the general contractor are basically responsible for this, but so far they don’t have any solutions. Has anyone experienced a clicking noise like this, or does anyone have an idea how to further narrow down the cause or what it might be? I can hardly imagine that we are the first and only ones dealing with such a noise. Any ideas, experiences, or tips would be much appreciated…

Every minute? Every hour? What is it?

ypg schrieb:

Every minute? Every hour? What is it?

The cracking happens in quick succession but is otherwise independent of the time of day. It can occur at 6 a.m., 9 a.m., or 8 p.m. So it’s more at intervals of hours rather than minutes.

Could the noises possibly be coming from the floor covering or the subfloor beneath it? For example, the material expanding or contracting due to heating or cooling, which could cause the clicking sounds? I’m not sure how your house is constructed, but since it doesn’t occur on the ground floor, it might be related to different materials used in the upper floor structure.

ChrizElard schrieb:

When all actuators are set to "manual," we could not observe the clicking noise.

ChrizElard schrieb:

The clicking does not seem to be related to the room thermostats – adjusting the temperature did not trigger the clicking noise.

I don’t understand, isn’t that contradictory?

If the noise disappears when the actuators are manually opened, would it be an option for you to disable the actuators and control the temperature directly via the heating system?
Many people do it that way here. It is more efficient and better for the equipment.

And in your case, maybe this also solves the "Casus Knacksus" 😉

Fuchsbau35 schrieb:

Could the noises possibly be coming from the flooring or the subfloor underneath? For example, the material expanding or contracting with heating or cooling, causing the cracking sounds? I don’t know how your house is built, but since it doesn’t occur on the ground floor, maybe it’s related to different materials used in the upper floor’s structure?

The construction on the ground floor and upper floor is the same. Concrete floor, with heating pipes embedded in the screed, and on top of that (installed by myself) impact sound insulation and laminate flooring.
If it were the floor, I would have expected the noise to change somewhat over three years, and not always sound the same. Is there a way to find out without having to break up the floor?