Pressurised system help...please!

[gmartine]

You have two problems...system pressure and run-on they are it appears unconnected.

Pressure - leaking TRV's/EV, dodgy filling loop.
Run on after complete switch off (your description) - Faulty controller/ PCB, valves, very odd.

 

[bowfer]

When I say complete switch off, I mean the timer controls.
They're both showing off, but the pump and boiler keeps going.
The pump gets progressively louder the longer it runs on, which I assume is because no water is going through it (the radiators do cool down)
If I press 'advance' and make the heating controls light up again, the pump goes back to being quiet after a while.
So it would suggest the pump is running on, but some valve or other is closing off water to it.
When I press 'advance' this valve is opening again and allowing water to go through the pump again.

 

[gmartine]

Wait for your engineer to turn up, get them to sort out the pressure/filling loop and point out the leaking TRV's. We can't accurately diagnose your run on issue remotely but as Best mentioned motorised valves can fail and energise your boiler and pump, get them to check that too.

 

[heatservice]

I have come across the boiler & pump running on a few times due to a 2 port valve actuator fault, valve closes but microswitch still in open position, water will then circulate through the bypass.

 

[bowfer]

Engineer came, unfortunately I couldn't be there in person but I spoke to him on the phone. He asked if I knew where some valves were, my wife advises he then 'changed some bits under the floor'. I also noticed he changed the fill loop pipe/valves. Fingers crossed the running on stops. Next move is to get them to change the 3 x leaky TRVS.
baby steps!

 

[Luke Warm]

The red bottle you talk off is the expansion vessel .what they have tried to do is repressurise it to try and solve the problem you've been having (losing water pressure). All this aside let's get down to the actual problem.
You've said you've been doing this for awhile, seeing that your system is old the first thing I would try is ;
Take a pz1 screwdriver and remove the black taps from the valve (s) try using an adjustable wrench or pliers to turn the spindle which operates the valve.
With frequent use this plastic taps wear and stop turning the valve, even when you think it is .
The red vessel may also have failed .
How often are / was you repressurising the syste

I was thinking the exact same i thought SSE would have picked that up On the levers though!!