Potterton 100e - Boiler, Radiator or System problem?

[Mitch05]

Hope someone can assist with this one.
I have a Potterton Puma 100e Combi Boiler and the HW output is fine. However the CH seems to be erratic. When it is On the 'Flame' light will click on a few seconds later but only stays on for a few seconds before going out again. Throughout the next while it will occasionally go on then off.

The downstairs radiator nearest the boiler is piping hot when fully on, but the others downstairs seem to be cooler or just cold. When I turn the nearest radiator off sometimes it helps heat up some of the others, sometimes not. I have tried heating with the TRVs off and they still remain cool which doesn't sound right. Then, at other times, after a while, they might start to heat up but its a bit of a lottery as to whether they work on not.

Upstairs is mostly warm and OK, though some radiators are cool occasionally.

All radiators have been bled.

Not too sure where the problem is. Could it be the diverter valve not drawing heat when on CH? Would that explain the issue or is it that the system maybe isn't balanced properly or some other more serious problem?

One final question. Lockshield valves...I was told that turning clockwise turns them Closed . Should it be the case that the furthest radiators should all be Open(ie turned CounterCW), and the nearest Closed(turned CW)? And should I be worried if water seeps from some the valves when they are turned?

 

[Mitch05]

Putting this one back to the top in the hope someone has some experience of this type of issue.

I tried balancing the system in case this was the issue. Wasn't too sure which method to use for balancing as I have seen both 'Open all valves' and 'Close all valves' methods so tried the first. The radiators closest the boiler (both up and downstairs) got really hot the others lukewarm or just stayed cold. I started balancing from the hottest onwards and it seemed to bring some of the other radiators to life but not all were as hot as I expected. The Flame still lit for about 20-30 s then stopped and this happened repeatedly. Also I notice that the nearest radiator lockshield valve is definitely leaking when you try to close it(not sure why). If I open it then it will take all the heat and the other radiators will turn cold (bit of a catch 22)

So in summary the two questions I still have are:-

1) Does it sound like this system has a diverter valve problem which needs the valve replacing?
2) How do I stop the lockshield leaking...is it as simple as replacing it and if so how?

Thanks in advance for any help from anyone on this.