vaillant no hot water or heating

[onion_soup]

hello

vaillant turbomax plus gives no hot water randomly and heating is also off at these times ( can not be turned on ). When water is hot it runs cold then hot again( but not always) from same tap, while filling bath or sink.
Error code checking from display shows last code as 'nnn' this maybe a red herring ?

ps

warm start light flashing during fault sometimes

 

[ChrisR]

Eeek. SOunds like more than one fault so the PCB has to be a suspect. Hot cold hot running is usually scale but if it's an 824/828/837 it's a bit new for that to be common.
If you need a board let me know - they're a tad expensive normally.

 

[blahblah]

nnn isn't actually an error code but a marker that can be put in to show subsequent error codes after service or repair. So it appears not to be showing a fault. Sadly I can shed no further light on the scenario.

 

[ChrisR]

I'd forgottennn all about that!

 

[onion_soup]

Eeek. SOunds like more than one fault so the PCB has to be a suspect.......

hi chrisR

its behaving almost perfectly now apart from hot cold hot water occaisonally.

How much for a new pcb ? Will wait for more symptoms ......

Any other advice ?

 

[onion_soup]

nnn isn't actually an error code but a marker ......

thanks blahblah had me scratching my head too !!!

Just checked for error codes previous to 'nnn' :

nnn
f22
f22
f22
f22
nnn

f22 is low water pressure ?

Would it reset itself after f22 error ? Is there a way to check date time of error codes ?

Just been on vaillant website and seen vrdialog software what is it for
( how much?) would it be of any use to me ?

 

[blahblah]

Soup- I think its the diagnostic software that their engineers have. No idea how much but it won't be cheap. There are more codes inside than you can get from pressing the buttons-sneaky! Last I asked a Vaillant call out was £90+vat etc etc. Will dig out their training manual to look up F22. Assuming its HW mains pressure the problem may be outside the boiler.
Chris- don't beat yourself up for forgetting something. I'm learning lots just by reading your replies. May be on bugging you lots if I get into breakdowns!

 

[ChrisR]

soup - about half partscenter price

 

[chowdrys]

Hi

I have exactly the same problem. The HW can go stone cold any time during a shower and then the boiler has to be restarted. The Temp starts to go up and then sometimes remains high with bursts of hot and cold water or the water can go cold again after 1 min or so. Model: Vaillant Turbomax 828E.

Please suggest solution. Appreciated.

 

[corgigazza]

These boilers early models have a faulty pcb that keeps giving the f22 fault, the fault is detected by 2 thermistors on the inlet and outlet measuring temp differences, the later boards increased the time limits but first make sure no other faults present eg pump jamming, aav not working, internal bypass clogged and all trv fitted.

Also you may have a faulty div valve but that does not bring up any fault codes.

 

[chowdrys]

Thanks a million for the invaluable advice.
I don't suppose you could tell me how to make any other checks before pinning the problem down to a faulty PCB?

The Pump seems to be working as when I touch the pump while the boiler is ON, although it's quite hot, there's some degree of vibration that can be felt.