Vokera linea 24 error 4

[davie]

Hi all, I've a 5yr old vokera linea 24. Been OK so far except for an 07 error about 1 year ago. Followed advice here and changed thermister and worked well till yesterday.
Problem was no hot water, error 04 flashing. Read manual, checked pressure (0.5 bar) refilled to 1.5 bar, reset for 10 seconds (and later disconnected from mains for 12 hrs last night)but on turning control knob to water or to radiator green light comes on for a few seconds and then changes to flashing red and error 04.
Read a post about sticky pressure switch so also raised pressure to 2.5 bar overnight when disconnected from mains. I noted that when I reduced the pressure by opening the safety the micro switch next to the diverter valve operated when water was flowing out of the safety valve.
I've tried to follow the fault guide but cannot decide if its a pcb board or pump fault. Since I've been quoted £250 for the pair any comments narrowing it down to either, or preferably a cheaper option, would be appreciated. Thanks in advance. Dave

 

[DEEARR]

Indication are that the pressure switch is faulty. If your are qualified/competent to carry out tests as per the electrical faut finding guide you should be able to identify the offending component.

£250 for the pair including labour is not far of the mark. Perhaps a second opinion could reduce the cost by locating the exact fault.

 

[davie]

Sadly the £250 was supply only, I'll get a multimeter on monday from work and try the electrical fault finding, thanks for the advice.

Dave

 

[Agile]

That boiler does not have a water pressure switch.

At a guess the fault code 04 is a lack of system flow.

Either no water or its blocked or pump is faulty or blocked or there is air in the system because the AAV is capped or blocked.

Its just possible the flow switch is stuck or faulty. It uses a magnetic shuttle which operates a reed switch. Sometimes the plastic shuttle jams and I suppose once in a million times the reed switch will fail. Once in 500 times the diaphragm will fail as well.

Tony

 

[DEEARR]

I think you are wrong Tony this boiler does have a Water pressure switch. It is located on the hydraulic Manifold as described by Davie.

 

[davie]

More info, I left it overnight with the selector switch in the central ...off... position. When I looked at it today the pump was very hot but pipes leading to and from it were cold. I think the pump is trying to run but I'm not sure why this would happen in the off position. I manually held in the flow switch microswitch and the boiler started to fire up... very quickly let go of microswitch and the boiler stopped firing up. I think that either the pump is air locked or broke. Since Ive done nothing to introduce air into the system I'm going to try fitting a new pump but I need to order one.

Is there a simple way to bleed the boiler of air in case im wrong?

Is there any other possible cause for the symptoms so far?

Thanks for all the advice, its really helping me think through the problem.

 

[scatmanjohn]

I think you are wrong Tony this boiler does have a Water pressure switch. It is located on the hydraulic Manifold as described by Davie.

Yes and No.

There are two versions of these boilers one has a boiler flow switch(early model) to detect the flow and the other relies on the system pressure being adequate so uses the low pressure switch.

Never seen one with a reed switch though.

I think you may be talking about the DHW flow switch Tony

 

[davie]

The manual fig 1 general layout indicates a "flow switch (boiler)" and a "Domestic Hot Water Flow Switch". The case has a manufactured 1999 mark. The only marked pressure switch is a pressure diferential switch that is located in the flue.

 

[Agile]

The one I am describing is the system flow switch and is fitted on the front of the left hand hydraulic unit.

It is similar to the Ariston, Biasi and Halstead and a few others that I cannot pinpoint after a press night at the theatre with the following curry supper and several glasses of wine. Its quite possible the reed switch is only used on the Ariston. The alternative is a conventional microswitch in a plastic case although I dont remember seeing one on the Linea hence my thought that it used the reed switch sensor.

If the pump is hot and the associated pipework cold then I would assume an airlock due to a capped or defective AAV. That diagnosis is confirmed by a lack of operation of the system flow switch thus preventing the boiler firing up.

Tony

 

[scatmanjohn]

The one I am describing is the system flow switch and is fitted on the front of the left hand hydraulic unit.

It is similar to the Ariston, Biasi and Halstead and a few others that I cannot pinpoint after a press night at the theatre with the following curry supper and several glasses of wine. Its quite possible the reed switch is only used on the Ariston. The alternative is a conventional microswitch in a plastic case although I dont remember seeing one on the Linea hence my thought that it used the reed switch sensor.

If the pump is hot and the associated pipework cold then I would assume an airlock due to a capped or defective APS. That diagnosis is confirmed by a lack of operation of the system flow switch thus preventing the boiler firing up.

Tony

I think the ruby and wine had gone to your head last night Tony.

Airlock due to defective APS ??

 

[weargas]

If it is the earlier linea with a flow microswitch instead of the pressure switch then I'm with Tony in it being a duff auto air vent (providing the pump is running). It is possible to vent the boiler (to an extent) through the front of the pump and it will get it working but it's better to change the AAV. Davie, I can give you a number of a reliable honest heating engineer in the toon area if you wish.

 

[scatmanjohn]

If it is the earlier linea with a flow microswitch instead of the pressure switch then I'm with Tony in it being a duff auto air vent (providing the pump is running). It is possible to vent the boiler (to an extent) through the front of the pump and it will get it working but it's better to change the AAV. Davie, I can give you a number of a reliable honest heating engineer in the toon area if you wish.

Tony reckons its the APS not the AAV.

 

[davie]

hi again, got the multimeter and power to pump but pump not working . New pump to order tomorrow £111.16. Was going to shop around but wife is reaching breaking point and the brothers sick of me popping in for a bath. Should arrive Thursday. I will post agaion with hopefully good news. Thanks again for the help.

Dave

 

[Agile]

Sorry folks, of course it was the AAV I meant but I had already explained my situation following the theatre evening.

I thought he said that he was satisfied the pump was working OK. If he is still reading this he could try spinning it as it may just be seized up.

He could also stop looking at the manual and look at the boiler and see what type of flow switch it has.

Tony

 

[davie]

Hi all, pump arrived today, 15 minutes to fit (only did electrics bit, not the housing and water connections) boiler started up first time. Me, wife and brither all happier people, thanks for all the useful advice. (next time I'll have the nerve to dismantle the pump to see if its broke rather than trying to guess the problem)
Thanks again ... dave