Abstract: A method of cooling a heating apparatus includes a heating chamber. The method includes accumulating condensate in the heating chamber, monitoring a pressure in the heating chamber, and controlling the pressure in the heating chamber by venting the heating chamber to thereby controllably permit vaporisation of the condensate that cools the heating chamber. The pressure is controlled to maintain a rate of cooling of the heating chamber within a predetermined range. A heating installation is configured to perform the method. A cooling unit may be connected to a heating apparatus to cool the heating apparatus using the method. A method may be used for retrofitting the cooling unit to a heating apparatus to form the heating installation.