Hi I have just found this great site.. Any ideas on this problem. I have a Vaillant turbomax plus 828E Combi. I Powered it off today While replacing a sink, Water was turned off and drained down. After refilling the system and powering on, the boiler shows Error Code F28. This relates to gas supply or ignition. The Sparker is sparking Ok. But it appears to be getting no gas. The gas supply is ok in the rest of the house. If you press reset it tries to ignite 3 times then F28! Please help its staurday night and its cold!!