VA6503 221 BF Diaphragm (hole in centre) VA6501 221 BF Diaphragm (no hole) VA6504 242/282 Turbomax Diaphragm VA7102 VCW 221 240 242E 280 280E DHW Heat Exchanger (upgrades from plastic) VA7101 VCW Sine 18 W/W Heat Exchanger VA7103 VCW 242E Heating Heat Exchanger VA0101 824 Gas Valve Honeywell VA0102 845 SIT Sigma Gas Valve (2 male connections) VA0103 824 Turboplus 845 SIT Sigma Gas Valve (2 female connections) VA8203 180-282 Diverter Valve VA8204 VUW 242/282 Turbomax Diverter Valve VA8208 828E Electronic Diverter Valve