Vokera Linea 24 stuck in pre-heat

[Adouen]

Inherited a Vokera Linea 24 with the house. Except for the periodic rattling noises things were working fine until two days ago when the rattling noise became permanent and the heating stopped being activated.
Hot water appears to be working fine and gas fire kicks in with demand but no central heating. The pre-heat function seems to be on permanently and disabling JP6 does not have any effect.

Any suggestions will be most appreciated.

 

[Agile]

It sounds as if the diverter valve motor has failed!

Didn't you manage to see where the rattling is coming from?

Tony

 

[Adouen]

Indeed, it did seem to come from the diverter valve motor and pump area. Any suggestions? Or just replacement.

May not be relevant, but water pressure needs to be topped up weekly without any leaks.

 

[Agile]

The gland which seals the pin the diverter motor pushes may be leaking and have spoilt the motor.

If you remove the motor then you should get heating.

Disconnect the motor plug and IF the pin is in the out position then replacing it will give you hot water.

Failed gland will be due to dirty system water. This should be treated!

Tony

 

[Adouen]

Many thanks. You cover W2?

 

[Terrywookfit]

The pin can also stick due to deposits on it !
Remove and clean it before changing gland! ( Green pan scourer)
You need a long reach socket to replace the gland !

 

[Agile]

We do cover W2 but would ideally wish to know if the gland has leaked before we come so we could bring the part.

Tony

 

[Adouen]

Will take a look tonight.

Thanks to both for your quick pointers.

 

[Gasguru]

The rattling is often the non-return valve on the right hand connection on the plate heat exchanger (primary side). I recall many rattle even when new.

 

[Adouen]

Took a look again and here are the symptoms.

When the motor is out and the pin out, heating works fine nice and quietly. Pushing the pin in, the rattling starts and the water temperature rises fast. Pushing in and out seems to have unstuck the pin but still feels sticky.

There does not seem to be any leak in that area. all components are dry.

 

[Agile]

Sounds to me as if the plate HE is blocked.

Although it could be the non return valve is stuck !

Perhaps the pin was stuck? But is the motor actuator moving to each position?

Tony

 

[Adouen]

The motor appears to behave as expected. Pin still sticky-sh and rattling persist, albeit reduced, in the valve area when pin in dhw mode.

 

[Agile]

Does it still rattle if you remove the motor and get DHW by pushing the pin?

Tony

 

[Adouen]

Yes. Seems like it has gone a bit better but it is linked to the pin being in wether pushed by the motor or manually.
Since I have been looking more into it, it also looks like dhw is slow to get going when the heating is on. May be irrelevant though.

 

[Agile]

The non return valve which can rattle is on the right hand said at the return connection from the plate HE.

Tony