Valliant Ecomax Hot Water problems

[Jobber1]

Hi

I have a five year old Ecomax 835E which has been totally problem free until a day or so ago.

We first noted a low pitch rumbling/vibrating noise coming from the boiler around a week ago but the boiler was still working fine. Now, since yesterday, any hot water demand results in the boiler lighting and heating water up to around 67o and then the burner cutting out. There is no fault code displayed and the central heating is fine. However, turning the heating off makes no difference to the hot water problem.

Can anyone please offer any theories or give me an idea of what I may be faced with here?

Thanks in advance

 

[gas4you]

Press 'i' and see what 'S' code is displayed when faulting.

 

[Jobber1]

No fault code is displayed when the DHW runs cold. Based on how another Ecomax 835 with exactly the same problem on this forum was recently fixed, makes me think it could possibly be boiler sludging?

 

[Agile]

You have not given the full story!

If the boiler is left with heating OFF and the hot tap is run and LEFT RUNNING for 20 minutes does the burner really stay off when it cools down?

I suspect it will come on again as it cools down and that the problem is a blocked plate heat exchanger.

Tony

 

[Jobber1]

Thanks for the replies......An update as I've had more time today to look at this.....

The DHW does not actually run totally cold but goes down to about 40o and obviously the burner is still running

With the heating turned off and hot tap left running for at least 15mins the water cools down (as above) to 40o and stays at that temp (does not heat up again)

Feeling the input pipe to the DHW Heat Exchanger, its certainly not hot (but is that because the boiler heat output is reduced because of a blocked DHW Heat Exchanger?)

Thanks again

 

[Agile]

To reach any conclusion I would need that actual FOUR temperature measurements of each of the pipes to the plate HE.

Tony

 

[gas4you]

The 'S' code is not a fault code but an information code.

 

[Jobber1]

The S code showing when the DHW runs cool is S14

Having another look, if I reduce the DHW demand (only half open the tap or less) then the water does not cool down!

Unfortunately, I can't accurately measure the Heat Exchanger pipe temps but by feel, all are lukewarm (apart from the mains cold in) when the DHW is running cool.

Hope this helps?

Thanks

 

[skowi187]

i would predict that the heat exchanger is possibly scaled up and the humming noise comes from the pump as there is an undesired restriction. just fixed this problem at work today which seems very similar to your situation. try turning the pump speed down. does the noise go away? if so then i am correct

 

[gas4you]

With S14 showing, the boiler is still saying the burner is alight in dhw mode, so if the burner has gone out, as you say in your first post, something is giving it the wrong info.

 

[Jobber1]

Thanks again for the comments

Just to confirm, as I updated yesterday, the burner is still running when the DHW cools down.

 

[Jobber1]

I've just heard from Vaillant who have cancelled tomorrows visit due to Engineer sickness!

It looks I'm going to struggle to get anyone to look at the boiler before Xmas.......So it seems I'll have to have a take look at the DHW Heat Exchanger myself (I am an Aircraft Engineer!) It looks straightforward but if anyone has any tips or if there is anything I should watch out for I'd appreciate the info

Thanks

 

[Agile]

Aircraft cool the oil and preheat the fuel with a heat exchanger so the principle is the same.

Dont forget to seal and then uncover the Peto ports!

Tony

 

[Jobber1]

It actually spelt "Pitot" Tony

 

[Deleted member 105431]

check the black flexi rubber hose for blockage, check the diverter valve moves freely, remove and clean the plate h/exch. I set these codes which seem to make them run better d1 to 8, d14 to 5, d71 to 70. You should range rate it using d0 too.