Potterton 80 L flashing green light stopping on

[paull123]

Hi all.
Can anyone please help ? Recently when hot water is on the flashing green light stops on permanently on the boiler. I have 2x2 myson 2 way valves on an unvented system in the airing cupboard. One for hot water and one for central heating. The 2 way valve stops on permanently for hot water with the pump consequently running. Even though no hot water is being drawn off. I have left hot water turned on for 12 hours but still nothing turns itself off. Boiler fires up OK when necessary but always goes into flashing green mode.
Now central heating when selected works fine. When boiler turns itself off on to steady red light 2 way valve for central heating turns itself also. One guy came round and said it may be the pump over run on the PCB. Now these boards are bloody expensive and I have heard of people having board replaced but faults are still there. I am pretty handy with a mutimeter. I have changed the motorised head on the 2 way valve but fault is still there.
If it is the pump over run would this not be the case as the central heating works fine ? Anything else I can check myself ? I am ok with diy.
Thanks for reading this post and any help gladly appreciated !!

 

[DP]

There are no ifs and buts or maybes.
Best to get someone who knows the boiler, how it works and how to diagnose it
Unless he is working on this boiler everyday, he will need boiler manual. If he is not sure and has not looked at the manual, then how can he be sure what the issue is
Can be the pcb or may not be the pcb
Good luck

PS. Sequence is once every 5 seconds when idle, demand applied then it is once a second, burner ignites it is solid green. If that is the case, nothing wrong with operation

 

[DP]

Slow to load, so double post now deleted

 

[Agile]

Paul, for the hot water valve to turn off, the stat on the cylinder needs to be satisfied ( set temp reached ! ).

It might be that all that is wrong is that the boiler flow temp is too low to raise the cylinder temp up to the set point of the stat on the cylinder.

If the cylinder hot water temperature feels about right, should really be about 60 C, the try turning up the boiler flow temperature. It must be set to about 10 C above the cylinder stat setting, typically 70 C.

Cylinder stats are not very accurate and yours, even if correctly set, may not be working well. Turning it down to below the actual temperature of the cylinder should cause the motor valve to close.

Tony

 

[AGAS]

Recently when hot water is on the flashing green light stops on permanently on the boiler.

The 2 way valve stops on permanently for hot water

is it me , this is confusing me

 

[DP]

is it me , this is confusing me

Me too

 

[paull123]

Well thanks guys it was the cylinder thermostat. I turned it down to around 40 degrees and like magic everything turned itself off. At the moment it is set to around 55 degrees and it works fine. Whether it was sticking or not I will never know but I think it struggles to get above this temp. I will try tomorrow. There are some really helpful people in this world. Thanks to you all for making the time to reply.

 

[paull123]

For what it is worth boiler stat was on around 3/4. It was set on higher but for some reason boiler kept locking out so had to reduce it slightly. Added some new inhibitor as none had ever been added for the past 15 years......

 

[JohnD]

have you held a thermometer under the hot tap yet, to find what the temperature really is?