Molten air and gases in service water turn into gas with the increase of water temperature and start to circulate with water in installation. Metal materials in the installation may cause noise, circulation impairments and cavitation in pumps just as corrosion Air penetration  into radiators

will lead to heat problems. As there is constant air intake into the system especially  in installations without oxygen barrier wher e plastic pipe is used and underfloor heating installations, this problem gets bigger.