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andriy_melnyko3 Mar 2024 14:56Hi everyone,
I’m looking for help to understand the behavior of our heat pump.
New build, 6 apartments in one building, built in 2022. Heat pump for hot water and heating.
The technical room is located below our apartment, where the heat pump is installed. Inside the technical room are two large compressors and one smaller compressor, see pictures.
Outside there are two heat exchangers with fans.
Depending on the outside temperature, we hear a loud humming noise inside the apartment. Sleeping is impossible.
From about +5°C (41°F) and above, there is no humming. Between +5°C (41°F) and -5°C (23°F) the humming gets louder and louder. Below -5°C (23°F) it remains consistently loud.
The compressors only have on/off control (according to the manufacturer), but the humming varies in intensity, even when all compressors are running – I have checked this.
The humming always has the same frequency – 146 Hz, see pictures.
Recently, an acoustic measurement was carried out. Before that, I coordinated with the company that built this heat pump to try a full load simulation, so we would be sure during the measurement. The technician came when it was +3°C (37°F) outside. He manually adjusted the setpoint for the water temperature, slowed down the outside fans, and manually activated the heat pumps. Then it hummed loudly. The technician said that by running the fans slower outside, the system simulates temperatures between -7°C (19°F) and -10°C (14°F), which increases the pressure difference at the compressors and can cause stronger humming.
On the actual day of the acoustic measurement, it was +10°C (50°F) outside. The same steps were followed, the fans were even slowed down more, all compressors were running, but there was hardly any humming. The acoustic measurement, which cost several thousand euros, was basically useless...
Does anyone have an idea why the humming is so dependent on temperature in this case? What exactly is causing the humming, or what could be transmitting it so well into the building, especially at such a distinctive frequency of 146 Hz?
And what could be done if we want to have it measured again?
Thank you very much!
Andriy
I’m looking for help to understand the behavior of our heat pump.
New build, 6 apartments in one building, built in 2022. Heat pump for hot water and heating.
The technical room is located below our apartment, where the heat pump is installed. Inside the technical room are two large compressors and one smaller compressor, see pictures.
Outside there are two heat exchangers with fans.
Depending on the outside temperature, we hear a loud humming noise inside the apartment. Sleeping is impossible.
From about +5°C (41°F) and above, there is no humming. Between +5°C (41°F) and -5°C (23°F) the humming gets louder and louder. Below -5°C (23°F) it remains consistently loud.
The compressors only have on/off control (according to the manufacturer), but the humming varies in intensity, even when all compressors are running – I have checked this.
The humming always has the same frequency – 146 Hz, see pictures.
Recently, an acoustic measurement was carried out. Before that, I coordinated with the company that built this heat pump to try a full load simulation, so we would be sure during the measurement. The technician came when it was +3°C (37°F) outside. He manually adjusted the setpoint for the water temperature, slowed down the outside fans, and manually activated the heat pumps. Then it hummed loudly. The technician said that by running the fans slower outside, the system simulates temperatures between -7°C (19°F) and -10°C (14°F), which increases the pressure difference at the compressors and can cause stronger humming.
On the actual day of the acoustic measurement, it was +10°C (50°F) outside. The same steps were followed, the fans were even slowed down more, all compressors were running, but there was hardly any humming. The acoustic measurement, which cost several thousand euros, was basically useless...
Does anyone have an idea why the humming is so dependent on temperature in this case? What exactly is causing the humming, or what could be transmitting it so well into the building, especially at such a distinctive frequency of 146 Hz?
And what could be done if we want to have it measured again?
Thank you very much!
Andriy
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andriy_melnyko4 Mar 2024 08:13sysrun80 schrieb:
Did you also open the valves of the underfloor heating/radiators in the apartments during the measurement? What about the pumps?Thank you for the first response! No, we have not checked the valves. Which pumps do you mean? What is your suggestion? We also tested it earlier: there is no humming when the compressors downstairs are off, a slight humming when only one large compressor is running, and a strong humming when both run. The small compressor has very little effect.
I have also attached a picture showing how it looks inside the apartment.
andriy_melnyko schrieb:
Thank you for the initial response! No, we haven’t looked at valves. Which pumps do you mean?The heating circuit(s) have pumps that may be modulated, meaning they are controlled according to demand.
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andriy_melnyko5 Mar 2024 13:07sysrun80 schrieb:
The heating circuit(s) have pumps that may be modulating, meaning they are controlled based on demand. Could you please explain a bit about the valves and pumps?
Can these pumps operate synchronously with compressors, or are they usually independent?
Can you see the pumps in the photos? I have attached a few new pictures.
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