Posted By John Donaldson Chris Its many years since I was involved with sprinkler systems but the following may be helpful. I would suggest you speak to your insurers, they may well have a view on this and may require that you use a specialist contractor. We were able to use our own pipe fitters for minor changes but any major work had to be carried out by a specialist contractor. Have you calculated the hydraulic effects of the changes you are considering? Again your insurers may wish to check these out. In the past the insurers who covered the site I was on always wanted to see the calculations before any changes were carried out.