Property is fierce.

Let's see if the exhaust pipe of their water heater is installed from the outer wall or the window beam. If it is, it is illegal. This behavior destroys the building structure, which will bring security risks, especially for high-rise buildings. If he declares the property management and the qualified design department approves the construction, that is another matter. You can complain about his behavior to the relevant departments, call the police or solve it through other legal channels. It should be supported by relevant departments.