With a new energy efficient boiler? Sulfuric acid at high concentrations in drain openers also. Safe alternative that really works! We can’t fault the quality of the job your guy left, and he was very tidy also, tell him well done! Follow us on social media to keep up to date with everything that’s happening... If a public drain is blocked, report it to us so we can investigate the problem. One thing that you need to be mindful of is the savings that you can make per month with the right boiler,.