Central Heating System Cleansing Certificate

You need the system CLEANSED, not necessarily power flushed. BS 7593 requires cleansing before a new boiler is commissioned and treats power flushing, mains pressure flushing and gravity flushing as equally acceptable; on a system in reasonable condition a thorough chemical clean can be enough. What the standard also wants afterwards is inhibitor dosed and an in-line filter fitted. Manufacturers including Worcester, Vaillant, Baxi and Ideal require evidence that the system was cleansed for warranty validation, so record the method you used.

BS 7593 covers the use of in-line filters, and boiler manufacturers set their own warranty terms, so check the manufacturer’s instructions. The CertBox checklist records whether a permanent magnetic filter is fitted and flags it if not.

Industry best practice is below 500 ppm. Readings above 1000 ppm indicate the system needs further flushing before commissioning. CertBox warns you if the reading is too high.