Worst nightmare. Installation took only 3 hours and the result was 1. They removed an old pipe and "forgot" to seal it. It took 3 visits for them to fix it ( they should have replaced the pipe but they only applied some silicone). Downstairs neighbour property damaged twice. 2. One month later we noticed a gas leak, they repaired it after saying 'it was only a small one'. Thanks God 3. They removed all the wall plaster when removing the old boiler (answer after complaining - check our policy) 4. They broke the back of all my kitchen cabinets ( to set tup the condensate pipe 5. Over a year later, we found that this condensate pipe is leaking, still investigating the damaged.