ᐅ Sulfur Smell in the Attic After Plumbing Work

Hello,
after a plumbing appointment took place in an apartment of a multi-family house, there was shortly afterward a sulfur smell coming from the water pipes in the apartment above (3rd floor attic). I am trying to find out where the sulfur smell could be coming from.

On the 2nd floor: The drains of the washbasin and kitchen were cleaned today, and an air admittance valve was installed at the sink so that the water flows out of the tap with the same pressure as before. In addition, radiators were bled, and the pressure of the central heating system was increased.
Can anyone help me?

The smell I know when bleeding a radiator could definitely be described as "sulfur-like."

Have you asked the plumber yet? That would be the easiest solution.