I think I have an open vented CH system with boiler and pump downstairs, hot-water cylinder in bathroom and 2 tanks in the loft.
My radiators keep sludging up and corroding so I have been intermittently flushing them out, and/or replacing them. 2 weeks ago I came home to a new water feature as one of the upstairs rads had burst. I drained the system and replaced that and another radiator and while I was at it removed and flushed all the other sludged radiators. I then flushed and refilled the system and bled the radiators as I have done before without a problem.
When I have done this before it has taken a few days on full heat for the hot water to work until what I have been told is an airlock clears in the cylinder (no bleed valve at top).
I went away on holiday hoping hot water would be there on my return but still no joy 2 weeks later. Also the hot water tap in the bathroom releases no water at all (all other taps work fine). The radiators are all working perfectly - hot house but no hot water.
Another concern is there is hot water flowing from what I assume is an overflow into the header tank and then out through an overflow onto the roof.
Any ideas how I can restore the hot water? how to get the tap flowing?
Why does the system keep sludging? why is it always overflowing?
Would a new system, combi boiler(??) be the long-term solution to all my problems.
Sorry for the essay but it's only by writing it out I've realised how many problems there are!