Neighbor finds the air-to-water heat pump too loud

Hello and a happy new year to you all.

The following, our neighbor was just here and complained that our heat pump is too loud and indeed runs continuously. The outdoor unit of the heat pump is located behind our house. On the property line stands the neighbor's garage, behind the heat pump is our garage, meaning the heat pump is positioned so that a kind of corridor/tunnel is formed. The neighbor's house is diagonally opposite. He said he constantly hears a humming. What do you think could be done to dampen the sound a bit?

If you have maintained the structural distance (usually 3m) to the boundary and no more than 35 dB reaches the neighbor, you should be safe.

Do you mean that the heat pump is placed in a corner? Unfavorable....

Otherwise, a soundproof cover would also be conceivable, which provides some dB reduction.

Yes, exactly, it is standing in the corner. It is about 50cm away from the garages on the left and at the back, and about 2.5 meters from our house.

acoustically extremely unfavorable. Together with the sharp angle, this is already a sound funnel. Would another location be possible? Is this a new building and what does the planner/heating engineer say about it? Such a thing should possibly be able to be criticized.

Yes, it is a new building or was built in 2017. I will write to the heating engineer.

Yes, it is a new building or was built in 2017.

And then after several years the neighbor notices that the heat pump is too loud? What kind of device do you have?