Vokera linea max central heating problem

[reb78]

Hi all,
First post, but have been searching on here for a while now regarding a problem with my central heating. The boiler is a Vokera Linea Max (not my choice, it was installed when we bought the place!)

The issue is that the rads and the heating get tepid at best. We have a home are agreement with British Gas, but even they seem a bit stumped on what the problem is now.

Hot water seems fine. The problem is that, when on heating, the boiler whizzes up to 63degrees on the display and then turns itself off for 2 mins before repeating the process again. It never seems to run hotter than this and the rads only ever get lukewarm.

Other posts point towards the diverter valve, and BG also thought this and so it has been overhauled with a service kit with no change to the problem.

At the same time, the boiler seemed to be getting confused as to when to switch to heating from hot water - the diverter valve motor didn't always seem to be in the correct position. As a result, the valve motor and also the Pcb were changed. So, this is what has been done so far by BG.

Unfortunately, none of this has solved the problem. BG then uttered the words powerflush at £750!! I hired a machine form Travis Perkins yesterday for £50 and spent about 7 hours flushing the system. I connected via one of the radiators, then I flushed with clean water for about an hour to remove loose sludge, then added sentinel x800 ran it round the whole system for a couple of hours, then turned all of the rads off and did them one by one (10mins on each) draining in between switching to the next one. I then did a final flush of the whole system once all the rads were turned back on. Unfortunately the problem persists!!!!

So, what next?? Any pointers would be appreciated. BG are supposed to be phoning Vokera, but I haven't heard back from them yet. The chaps who have been out so far seem to have been pretty thorough, but I could really do with some help with this otherwise this house will be cold all winter!

As I say, Ive searched old posts and diverter valve and or motor seem to come up, but these have been replaced.

Thanks in advance!

These are the boiler instructions:
http://vokera.co.uk/wp-content/uploads/2009/04/linea_max_installation_and_servicing_instructions.pdf

 

[Agile]

Did they never change all the temperature sensors early on?

BG usually have an arrangement with manufacturers called a "joint visit" whereby a Vokera staff engineer accompanies them when they cannot find a fault.

In my experience BG can easily be stumped! I once solved a problem with them after they had made 23 visits. I did not even need to go there and solved it with the BG lead engineer over the telephone.

Tony

 

[reb78]

Thanks for the reply Tony.

One sensor was changed, but that was the domestic hot water temp sensor. I think it got knocked and snapped as they were looking at something else. No other temp sensors were changed. They reckoned it was more likely a flow obstruction, but I'm open to ideas.

 

[Agile]

If the temperature does not reach the correct value then all the sensors should be checked.

Thats easy but many just replace them as they are quite cheap.

I doubt that they are the problem but just to eliminate them they should have been checked/replaced at the beginning.

Tony