Another Vaillant F62/F27 query - advise please

[Dan Vittori]

Hi All

I have about 7-8 year old Vaillant Ecotec plus 831 R1 Combi boiler which has been running fine for last 5 years since I moved in (only threw F75 once couple of years ago).

Two weeks ago it showed F62 error code which on resetting changed to F27 and on second resetting disappeared. The same thing repeated after about 5 days. Had to switch off the boiler a week ago as was going away. After restarting yesterday, it showed F27 error direct on hot water demand (no F62) and fault kept reappearing after resets. Tried the hair dryer trick (as mentioned in another thread) and it worked! Restarted after an hour, F27 reappeared and again reset didn't help. Removed fault code and left on overnight. Tried hot water demand again in the morning which showed F62 first this time followed by F27. After reset the boiler is working fine now with family taken shower etc.

There are no visual signs of issues with the PCB or elsewhere in the boiler except the AAV has dried out stains showing previous leak. Considering the hair dryer trick on PCB worked and the boiler is working now again, my money will be the faulty PCB (literally as well) as it would be a matter of time before it packs again.

Wondering what would be my best option from here. Shall I buy replacement Vaillant PCB online and get a Gas Engineer to change it or get the Engineer to diagnose it first or I shall go for a yearly plan and hope the boiler will survive any initial check and exclusion period or anything else.

Any advice would be highly appreciated. Thanks in advance.

 

[Hason]

Just get Vaillant out pay 275 gives u parts and labour for a year

 

[Rodabod2]

In case it’s helpful to any electronic engineers here, I took the advice to re-cap the electrolytics on my Ecotec Plus 831 after it occasionally had an F27 fault and it’s now fine.
I measured the ESR on each cap and it was one of the smaller 470uF (or was it 220u?) caps which had risen to 40 ohms. There were two of those caps and only one had failed. The other was closer to 0.1 ohms.
I’m guessing that the temporary hairdryer fix works because higher temperature lowers the ESR of the failed caps. I might measure one when it is heated to see if this is true.
All of the capacitance values were still within tolerance.