Vaillant 828e turbomax 7 yrs old

[ste131313]

Hot water is not getting hot enough.

Problem started 2 months ago when first thing in the morning it was cold then started to get hot then cold again. ( Boiler was switching on and off )

Usually after leaving it for 30 mins it seemed to be ok. Then it seemed to just get warm instead of hot. Have changed all 3 ntc`s last week but this has made no difference. Central heating is working ok.

Fault code showed F11 before replacing all NTC`S but now it shows F64.

Water is warm although temp gauge on boiler reads 72 degrees

 

[Deleted member 105431]

blocked plate heat exchanger

 

[ste131313]

is that the DHW heat exchanger

 

[Deleted member 105431]

is that the DHW heat exchanger

yes

 

[BGEngineer]

More than likely the Plate to Plate, but I would also check the diverter valve isn't sticking, they have a habit of doing this on these models.

With the boiler off keep your hand on the central heating flow pipe and then get someone to open a tap, if it starts to rapidly heat up the diverter needs servicing.

 

[ste131313]

More than likely the Plate to Plate, but I would also check the diverter valve isn't sticking, they have a habit of doing this on these models.

With the boiler off keep your hand on the central heating flow pipe and then get someone to open a tap, if it starts to rapidly heat up the diverter needs servicing.

Would it be easy to tell by looking if the DHW heat exchanger was blocked, I removed it last night and ran cold water through it, it seemed very clean and flowed easily. It made no difference to the water temp though.

Last fault code is F 64 irreversible electronic system malfunction.

I had thought the temp reader may be wrong, reading low and had thought maybe a new pcb would sort it.

Fitted a new diverter last year about this time.

 

[Deleted member 105431]

More than likely the Plate to Plate, but I would also check the diverter valve isn't sticking, they have a habit of doing this on these models.

With the boiler off keep your hand on the central heating flow pipe and then get someone to open a tap, if it starts to rapidly heat up the diverter needs servicing.

Would it be easy to tell by looking if the DHW heat exchanger was blocked, I removed it last night and ran cold water through it, it seemed very clean and flowed easily. It made no difference to the water temp though.

Last fault code is F 64 irreversible electronic system malfunction.

I had thought the temp reader may be wrong, reading low and had thought maybe a new pcb would sort it.

Fitted a new diverter last year about this time.

f64 can be a faulty pcb or defective earth. It can also be caused by an external electrical fault (I've had a defective tumble drier cause it)

 

[BGEngineer]

Its very difficult to see if a plates blocked up. A good indication it is is when you wash it out you initially get lots of black flakes come out. Did you try the test I mentioned, I know you had a new Diverter but they can still sdtick and let by and therefore heated water which is meant to go round the plate can escape down the heating flow.