Vokera Linea No CH

[g6mk]

My vokera linea 28 has only been giving hot water in the last few days.
It seems "stuck" in DHW mode unless it gets turned off.

The diverter valve moves freely and taking the motor off gives CH as expected. The problem seems to be that the motor pin is always in the out position. Checking voltages at on connector shows that the brown one from the PCB is the one constantly live.

Do I need to replace the PCB?

 

[scatmanjohn]

When you turn the selector knob to the middle does the display go out or stay on?

If it stays on the problem is the selector knob is snapped off and its stuck in hot water mode.

if it goes out then it something else

 

[g6mk]

When the selector is in the middle, the display goes out as normal.

 

[g6mk]

The latest update is that now CH started working while DHW does not. The live connection to the diverter motor is now brown and does not switch to black irrespective of whether there is DHW demand when in CH/DHW or DHW mode.

 

[Agile]

If you remove the diverter valve actuator then with the diverter valve pin out its in CH mode and will go to DHW mode with the pin depressed.

I thought the connector to the actuator was encapulated and you cannot see the colours of the wires.

The centre is neutral and the 240v is switched to either side according to the current operating mode. You could hot wire to an external supply on test!

If the voltage is not being switched then it would indicate the the operating coil of the actuator switching relay has gone o/c

Tony
G8ABQ

 

[g6mk]

I check the voltages at the PCB level where the colours are visible. The motor is working fine when tested with an external supply.
Now the situation is reversed, there is central heating but no DHW. Here is what I have observed.

Two days ago, with the selector knob in either DHW or DHW/CH, DHW was constantly on, going to max temperature and CH not coming up. The diverter valve constantly set to DHW and would not go to CH. That was two days ago.

Since yesterday quite a reversal. CH on when timer or manual activation kicks in but no DHW irrespective of whether the selector knob is in DHW or DHW/CH. The diverted valve goes to the DHW position when CH is off but there is no hot water drawn.

Any thoughts?

 

[Agile]

Is the DHW demand switch operating?

Tony

 

[Paul Barker]

Is the pushrod in the body of the diverter valve stuck?

 

[g6mk]

When I open a tap in DHW mode, the pushrod of the diverter is "pushed in" ie normal and the voltage at the DHW Flow switch terminals is 5V.