the flow and return from this boiler T's off to then go 2 ways; one to the front of the flat and one to the back of the flat. the boiler is about 8 yrs old. the pipe work is new and was run in plastic 18mths ago. the system worked fine 
all last winter and then the central heating was not used again at all untill the onset of cold weather this winter. the problem is that the heating is fine at the back of the flat but does not circulate the front part at all 
. the back part of the heating can be completely isolated by isolation valves. when this is done the boiler will not fire at all. we have tried flushing the front part of the system. maybe it needs a chemical flush...but after 18mths??
Anybody got any ideas?
all last winter and then the central heating was not used again at all untill the onset of cold weather this winter. the problem is that the heating is fine at the back of the flat but does not circulate the front part at all . the back part of the heating can be completely isolated by isolation valves. when this is done the boiler will not fire at all. we have tried flushing the front part of the system. maybe it needs a chemical flush...but after 18mths??Anybody got any ideas?
