Central Heating

Combi boiler constant breakdowns

Anonymous user 09/03/2024 - 3.10 PM

I have an incredibly frustrating issue with my Combi boiler (Worcester Bosch greenstar - three years old.) Once a year the plate heat exchanger breaks down and has to be replaced. This has happened three times now and the various engineers have advised that a 'grit' like substance is clogging the heat exchanger. The second time this happened we had a magnetic filter fitted (on the return) that I was told would pick up the particles and prevent them from getting into the boiler. Same problem around a year later. The filter was checked and was perfectly clean. So whatever is getting into the system is bypassing the filter somehow. The engineer scratched his head and suggested a mains flush of the system. A flushing/cleaning fluid was added to the system and left for a week before the flush. Very little dirt came out of the system. Out of desperation we fitted a second filter onto the flow. The magnetic filter on the return is a WB with a gravity filter so should catch all bits even non magnetic ones. It seems as though the boiler has broken down again today. Where do I go from here?! I should mention that we have some cast iron rads on the system. We contacted the manufacturer and they were adamant the rads aren't the issue, and if they were shedding bits of iron into the system then why are the filters spotlessly clean? The copper pipes that make up the majority of the system are probably fairly old, but if they are shedding crud, why did nothing come out in the flush? Any help greatly appreciated. I should add that the correct amount of inhibitor has always been present in the system. At least in the 3 years I have been here.