Vaillant EcoTEC Plus F27 Error: Flame Sensor Issues & Troubleshooting (VC PL306/3-5)

Question

Hi. Yesterday (Saturday) evening, the stove displayed error F27 and does not work. The manual says: meaning - foreign light source, cause - faulty flame sensor. I honestly didn't find something like a flame sensor (but maybe because I'm rare in this topic). What I have done so far: 1) I...

waldi644 · Answer

Emergency shutdown: flame simulation - Wet electronics, defective electronics (flame control), leaking gas solenoid valve

Piter.Krr · Answer

Thanks for showing interest.
Wet electronics - that's why I dried it
Damaged electronic system - I would love to find out what the most common causes were and proceeded to action

leaky valve - no smell of gas, if that is any indicator

ls_77 · Answer

Did you reset the boiler by accepting the error with a button with a crossed out flame?
Did the boiler turn on then?
When does F.27 error pop up? During the operation of the burner, how does the flame burn or after the end of the operation of the burner - after the flame goes out?
The fact that it signals a "foreign light source" means that the electronics still reads the ionization current from the electrodes after the signal, turn off the gas valve and burner.
Maybe you have a lot of impurities in the combustion chamber that get very hot and after turning off the gas valve and the burner, the electronics reads that there is still a flame on the burner? Maybe the gas valve does not close properly and still lets in small amounts of gas and the flame is still burning after the signal of gas closing? Can you see any of the above through the burner inspection window?
Or maybe the motherboard?

Piter.Krr · Answer

answer That's what I did, then the boiler turned on again, trying to work (it takes maybe 10 seconds) and again the error and silence answer It pops up every time you start it, that is, it doesn't even ignite. answer I think it's out because the flame hasn't been on since Saturday night. answer Right, but what about her? Maybe there are some typical faults, some parts that need to be replaced. I have some electronic components at home, but little knowledge.

ls_77 · Answer

This is not a common and repetitive error. I've never met him before.

Piter.Krr · Answer

What else did I do:
I checked for gas

- I checked that there is no voltage to the gas solenoid valve
- I checked the gas solenoid valve giving 24V voltage, the solenoid valve works (of course with the gas valve turned off in front of the stove)
- capacitor C702 is charged with 110V
- capacitor C3 is charged with 313V

Please help.

pepe__75 · Answer

Hi. I have exactly the same problem as you, except that when my boiler went into failure for the first time, it displayed error F.75. Then I reset the boiler. From then on, only error F. 27 appears. However, I have the impression that the pump makes a different noise than during normal operation.
Have you solved your problem? If so, tell me how. Thank you.

VPS · Answer

With error F.27 in 95% the electronic board needs to be replaced. The remaining 5% is the electrode to be replaced. Perhaps the x20 connector on the electronic board is wet.

kredar · Answer

Hello I have the same problem. Pressing the button with the crossed out flame several dozen times helped until today. Unfortunately, I can't run the furnace this way at the moment.

ROWE · Answer

The electrodes in photo # 9 should be cleaned to a metallic sheen, that's the basis.
You can replace the 3 largest electrolytic capacitors on the board, it helps. There are descriptions on the forum.
It is also worth checking the resistance of the NO and NC contacts in the relays.
If that doesn't work then the board needs to be replaced.

pepe__75 · Answer

It worked!!! The boiler has started!!!
But one thing at a time: the X20 connector was dry, I cleaned the electrode to a metallic sheen - it didn't help, so I thought it was a disc, I even found one in a nearby Vaillant store for PLN 1022, but I wouldn't be myself if, using your glad he didn't try to fix it. So I bought 3 electrolytic capacitors for PLN 7.80. I replaced the two smaller ones out of the three and it was "shot 10". The boiler has been heating for 3 hours. But I'm happy

To clarify the information: the repair concerned the Vaillant VC PL 186/3-5 boiler, on the board no. 0020035421 I replaced 2 twin capacitors 470 uF 35V.
Thank you all for your help!!!

ROWE · Answer

Well, I am full of admiration, as for an amateur, you have 1000 zlotys ahead! This applies to most old discs and also error F75, 61. Practice makes perfect.

Dbdavi · Answer

I have the same thing, do these capacitors need to be entitled somehow or can they be replaced non-invasively?

pepe__75 · Answer

I don't quite understand the question. What does entitle capacitors mean? You have to desolder old capacitors and solder new ones in their place. This means that you have to remove the board and use at least a soldering iron, replace the capacitors and reinstall the board. I don't know if these activities can be considered invasive or not? The disassembly and assembly of the board itself is not difficult, when replacing capacitors you need to have at least minimal skills in using a soldering iron. I'm not an expert, but I did. The boiler is still working.

cynk23 · Answer

Hello. Is five still going? I have a similar problem for a few days, first there was an error F62 after a reset, five went for several days and now displays F27 again reset five goes one day and again blonde F27 this time Mosze reset a few times and will surprise. What model do you have oven. Mine is eco tec plus 186

pepe__75 · Answer

Good morning, yes the boiler is still working. I confirm that in my case, for the error F.27 and the lack of boiler operation, the replacement of capacitors was an effective and effective repair. Yes, after that repair, the boiler once again refused to cooperate with me, but the problem was the worn out circulation pump. Then the F.75 error appeared (but it's to be checked if necessary, because I'm giving it off the top of my head). Yes, I have a Vaillant VC-PL 186/3-5 boiler.

toretto25 · Answer

Pepe, can you mark on the drawing which capacitors you replaced? I have the same problem.

toretto25 · Answer

Thank you very much, I will delegate it to someone else. I'll let you know how the replacement went. For now, I have a new one from a service friend.

Added after 1 [minutes]:

So blue and the two black ones?

Added after 40 [minutes]:

Pepe or start with two twins and possibly the big one? I am a complete layman

pepe__75 · Answer

Yes, two black 470uF and a blue 100uF.
I don't know which one was faulty because I replaced all three at once. I recommend you too, the cost is small, and they get damaged over time, so there is a probability that even if you hit the one that was damaged, the next ones will be damaged in a moment.

toretto25 · Answer

Pepe, thank you, one of the twin small ones listed two, the 400v one stayed because it is working. Thanks again for your help.

lechooo93 · Answer

I had the same problem myself. The capacitors were in good condition, so I cleaned the contacts with a contact cleaner and it helped - specifically the contacts from the electrode (ground + this pin). For future generations, I recommend giving it a try

mmaciaszek · Answer

Does anyone know the dimensions of this large 100uF 400V capacitor? Does it have long thin pins to solder or short thick ones?

rnb_bolii · Answer

Each new capacitor has long legs. So what's the problem ... I can put it in.

mmaciaszek · Answer

Some have these short and thick legs . They also have different diameters and heights. I would like to have this data to buy the right one without disassembling the board first.

pepe__75 · Answer

If I remember correctly they were thin long

VPS · Answer

original desoldered

szymanek732 · Answer

I dried the plate and started from where the moisture came from

Jabbi · Answer

I'm struggling to get the plate out of the boiler. Unfortunately, cleaning the electrode and drying x20 did nothing. Does anyone know if the c25 / c27 connector (yellow-green cables) is pulled out or should it be desoldered?

Vaillant EcoTEC Plus F27 Error: Flame Sensor Issues & Troubleshooting (VC PL306/3-5)

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