Vokera Linea 28 Error Code 04

Please help!

I have a Vokera Linea 28 boiler installed by a Corgi engineer in 1999 and regularly serviced.

There has been an ongoing problem since it was about 18 months old which is becoming steadily worse and more frequent. Several attempts to rectify on numerous occasions by 3 different Corgi engineers have all been unsuccessful.

Basically the boiler locks out showing code 04. This tends to occur when the heating system is cold and we try to turn on the heating or run hot water. In the winter it can occur daily. Over the past year or so it is becoming increasingly difficult to reset.

When it occurred last week I spent about half an hour switching it on & off, adjusting the temperature controls, leaving the hot water tap running, etc. During this process, as well as continually returning to code 04, once or twice it showed code 03. Eventually it settled down and hasn't tripped since but we have deliberately avoided letting the heating go too cold by leaving the room stat set to 17-18 degrees instead of using the timer.

Over the years, various Corgi engineers (some from a company recommended by Vokera) have been unable to eradicate the problem despite "recharging the expansion tank, cleaning the fan venturis, replacing the pump flow stuffing box, the selector knob and the dhw heat exchanger".

The pressure guage reads about 1.8 when cold and up to 2.4 when hot.

I would be extremely grateful for any suggestions of things I can try (I'm an electrician) or info I can pass on to the Corgi engineer. Many thanks.

04 from memory is low water pressure. assuming your guage is working and reading 1.5 bar then would indicate a fault with the switch itself

Cheers rob.

If you mean the reset switch, I think its ok as it does turn the unit off.

When I switch it back on it tends to run ok for a few seconds before locking out and showing the error code.

some linea models have an actual mechanism inside the boiler connected to the pipework and makes or breaks a contact if there is enough pressure.

others have a pump flow switch instead which again makes a contact when the pump runs. both are located just to the right of the pump
check these out

Maybe time to change PCB

Sounds like a typical problem with Vokera - my boiler (Vokera Eclipse) is doing exactly the same : the pressure seems to drop of its own volition once the heating reaches desired temperature and then 04 38 flashes and I constantly have to nurse it back to life. I now have to set it at 61 degrees to keep the heating running constantly (too hot!) I have the Installation Manual which indicates 04 is an electrical fault but the exact fault code (ie 38) doesn't appear - every other number does!!

Sincere apologies for my lack of replies to those who kindly responded to my plea for help a few weeks ago (my pc did an impression of my boiler then packed up altogether).

Fortunately Santa brought me a new pc but sadly not a new boiler.

As is often the case, the boiler settled down for a while but has started playing up during the cold spell. Today it has locked out a couple of times (code 04) and been very difficult to reset despite the pressure guage reading around 2.0.

Maybe it is time to try changing the pcb as suggested by sime10. Can anyone advise me of a stockist of the pcb? And being a sparky, is this a task I can carry out myself or does it take some setting up once fitted so should I get my Corgi engineer to do it?

Cheers again.

From what you have said it seems that you have ignored what Rob has told you.

If the code is for low pressure than thats what the boiler thinks is wrong.

You should try to decide if your boiler has a flow switch or low pressure switch.

Lets assume its a low pressure switch. Both types often leak but I think they are located on the left hydraulic block and not by the pump as Rob suggests.

Whichever type it is I suggest you replace it and check carefully that the water ways are clear when you do it.

Tony

Many thanks for your reply Tony.

No, I did act on rob's advice. I located what I believe is the boiler flow switch with the aid of the manual and rob's directions. It's located on a block at the bottom right hand side of the pump. When I first checked it (visually) I think I wrongly assumed it was ok because the micro switch appeared to be pressed in when the boiler was operating ok and when the error code 04 was showing .

I think I also assumed (wrongly) that the "Vokera specialists" who have looked at my boiler and who first suggested it might be the pcb would have checked something so fundamental.

The system locked out again this morning, showing code 04 as usual. As you suggested, I again checked what I believe is the boiler flow switch (this is a brass object with a plunger which operates a black micro switch). As I touched the metal arm of the micro switch, the fault cleared and the boiler started up but there didn't seem to be any movement on the switch itself. I think the brass plunger is fully out and operating the switch. And there is no movement on the body of the switch.

I have noticed that by slightly waggling the metal arm of the micro switch, the fault 04 briefly occurs even though the switch does not appear to click open.

Am I right in assuming the switch is closed under normal circumstances but when the flow is too low the plunger retracts , the switch opens, and error 04 occurs?

I am beginning to think it's nothing more than a faulty micro switch. Please let me know what you think. Cheers again.

Yes much more likely than faulty board.

Hi all,

I had the same problem and had Vokera come out to fix it....

Its a temperature sensor that has gone wrong.... a teeny little thing.

Once he swapped the new one in the problems dissappeared.... easy

It's usually the flow switch as you say. The pump runs for about 30s and if the microswitch hasn't made you get error 04. Could be muck, sticking, or a worn diaphragm.

I am confident in saying it's the flow switch needing replaced, as not many have seen this error where although the microswitch they're shows 04, it can also randomly show 03 as well, which is bizarre because thats a fan/flue fault. I have seen a good 3 or 4 though for this problem described, changing the microswitch sorted this error.