The block of 30 flats that I live in was built in the 1960s and the hot air central heating units are beginning to fail.New units are extremely expensive and the alternative of a combi boiler and radiators has been opted for by a couple of flats. My question is this.Is it permitted to put the flue outlet onto the balcony ?Also is it permitted to put the flue outlet less than 6 feet directly below the opening windows of the flat above ?