This all comes down to the system's BTU (British Thermal System, which amounts to 0.293 watts an hour per BTU). https://m.dukaaif.com/member/login.html?noMemberOrder=&returnUrl=http%3a%2f%2fFootballzaa.com%2Fout.php%3Furl%3Dhttps%3A%2F%2Fmuswellhillairconditioning.co.uk