Usually yes — if your existing system is more than a few years old, has cold spots at the bottom of radiators, or has never been flushed, a power flush is the sensible first step. Over time, iron oxide and debris build up in the water and settle in the radiators and heat exchanger. That sludge is the single biggest killer of boilers and pumps, and most manufacturers require evidence of a clean system to keep the warranty valid. We carry proper power-flushing equipment and use a chemical clean followed by a system inhibitor, so the new boiler (or the existing one) is protected from day one. On some cleaner systems a magnetic filter plus a chemical clean is enough — we'll tell you straight at the survey.