The Discal dirt and air separator is manufactured from epoxy coated steel with a stainless steel internal element. It is used to continuously remove debris and air contained in the hydraulic circuits of heating and cooling systems. They are capable of automatically removing all the air present in the system down to micro-bubble level, with very low head losses. The large air collection chamber is able to accommodate a large volume of air before being released automatically. At the same time they separate debris and impurities contained in the system which collect in the lower part of the collection chamber from which they may be expelled via the blow down valve. The circulation of fully de-aerated water enables equipment to operate under optimum conditions, free from any noise, corrosion, localised overheating or mechanical damage, important for reducing energy demands and on-going running costs.