I had a combi boiler replaced by the retailer, all good have post fitting check list. I fired it up early Feb all good. I assume that the post fitting and my test was just a quick fire up, water getting warm, heating working, and turn off. I've fitted a Gas it cylinder which came with a new pigtail hose that does not have the little button to press, do I need it? Anyways fired up the boiler all good, water to hot and heating warmer than outside, thought may as well try it on mains and yes heating and water still good with gas deselected. Good you would think, no carpet was wet. Where the, and I use the word loosely, technician had connected the water in to the drain valve the new hose had split, clamp over the top and it looked fine. Now I did not check for leaks when I did my test, but it is obvious that it was seeping at the join. Removed the hose and trimmed an inch off refit and all fine. Don't know how many a car engine hose I've that to over the years. Moral check work done to your vehicles. Stay safe and happy motorhomefun.