Fernox Central Heating Leak Sealer F4 Express 265ml

You don’t see anything happening;but have to hope the leak stops;if so the pressure in the boiler will remain steady;if not there is a chance you have a fault in the boiler:[. Pressure valve or exspantion chamber etc) all can be fixed ferly quick;

Genius product. My brand new Worcester boiler CDI 30 Greenstar was losing 0.5 bar every two days. I had the boiler checked and it was perfect - no surprises, as its brand new. There was a leak on the sealed central heating system and I could not see or find it anywhere. I bought two of these cans, isolated one radiator, injected by cans, fired up the CH system and bingo, 24 hrs later the pressure held and it's still holding a week late.Very Very Very Happy!

Very good