Where to start, most boiler installations i come across (i do over a thousand jobs a year) are fitted badly with the basics just not being done, installers/electricians would rather open the Star than the instruction book which has pictures so you don't even have to read it, because of this problems are very, very common from one off builds to large sites, what would normally happen is on the one off jobs the installer will guarantee the boiler for as long as it takes to get to the van and on the bigger sites the builders just don't tell any of the house holders with the hope the boiler warranty runs out before the faults show there ugly head, the sort of things i come across every day would be flow and return to small, gas pipe to small, boiler output to small, rads to small, pumped mains water, break tanks the size of a bucket, incorrect wiring, earths being used to carry 240v, no earth to boilers, no flushing, no inhibitor, no discharge pipe work, plaster in the boiler, boilers not commissioned, no ventilation, gas leaks, water leaks, boilers running with clock in the off position, room stats that turn off the hot water, room stats over rads, i could go on but i am boring myself, every one of these faults just shouldn't occur there covered in the manufactures instruction with pictures. The only job i know of that has ever been put right by the installer was one DGOBs sorted by throwing his weight around as a registered gas installer, by him doing the right thing could have effected his future business in the area, it did help with the decision making that every house on the site passed by Bord Gais risked carbon monoxide poisoning due to the laziness and stupidity of the installers, in saying all of that there are still good installers but i only get called in after the bad ones, people tend to have themselves to blame by always going for the cheap installers, they tend to get Muppet's and chancers, while the installers who stand by there work tend to lose out due to under cutting, if you can come up with a answer i'll put work your way, Gary.