Your original post asked whether as an unqualified DIY'er you could replace a blown immersion element on an unvented cylinder...The overwhelming response was NO and you were advised to have the work done by a G3 qualified engineer..You've confirmed the element has failed, told us how much you can buy a replacement for and the cost of doing an unvented course with Gledhill...so maybe you should do the course, get your G3 ticket, buy the part and do the job because I don't think we are likely to change our minds!!..I'm out too.