Vaillant Ecomax 828 fault

Hi Guys,

Firstly i'm glad to have found this site and apologise for my first post being a question. I doubt there is much in this forum that i can answer but plenty in others hopefully.

As above i have a Vaillant EComax 828E which has developed and intermittent fault.

I had the boiler installed 3.5 years ago as the one that was here had a hole in the water jacket.

Over the last 2 months or so the boiler has started to come up with error messages, these are as follows starting with the oldest first:

E13: Water Deficiency Error (maximum temperature rise of NTC1 has been exceeded. Appliance blocked for 10 mins)

F23: Water deficcieny protection activated (1, Insufficient water in primary heat exchanger, 2 lack of pressure in system)

The above probably started a month or so ago and the pressure was low on the CH system, reading nothing on the pressure guage. I have topped the system up and bled all the rads, after a few days it was fine for the next 4 weeks.

Yesterday i got the following error:

F00: Interruption of flow NTC (NTC1) (Loose wire\poor connection to NTC1, 2, Defective NTC replace NTC 1)

After this the boiler shuts itself down sporadically until i press the reset button and then runs for a random period of time.

From what i can see from the manual NTC1 and NTC2 form a potential divider which feeds back into X4\01, X4\02 and X4\03 which i'm certain are feeding back into a comparator on the main PCB but i don't have a circuit diagram for that.

Have any of you come across the symptoms above before?

My gut feeling is that i either have a dry joint on the PCB or failed comparator.

The other is that NTC1 is faulty as all the errors seem to point in that direction, any one know how much these are?

Many thanks for your ideas and input.

Jon

I am amused at your ( correct ) analysis of the circuit.

But you have failed to note that it then probably integrates the readings obtained as well as limiting the difference in readings to identify water flow faults.

I expect that the fault is with the NTC rather than the PCB. The NTCs are severely thermally cycled when the boiler is operating whilst the PCB is nicely insulated in a plastic box.

It may be better to replace them as a pair.

Most Vaillant parts are not that cheap and I seem to recall about £23 each but that may be a little bit out.

Of course as always when miles away I might be wrong and your pump could be sticking or the PCB could be faulty.

There is also a lesson to be learnt from honest engineers who replace the cheapest parts first !!!

Tony Glazier

Agile said:

I am amused at your ( correct ) analysis of the circuit.

But you have failed to note that it then probably integrates the readings obtained as well as limiting the difference in readings to identify water flow faults.

I expect that the fault is with the NTC rather than the PCB. The NTCs are severely thermally cycled when the boiler is operating whilst the PCB is nicely insulated in a plastic box.

It may be better to replace them as a pair.

Most Vaillant parts are not that cheap and I seem to recall about £23 each but that may be a little bit out.

Of course as always when miles away I might be wrong and your pump could be sticking or the PCB could be faulty.

There is also a lesson to be learnt from honest engineers who replace the cheapest parts first !!!

Tony Glazier

Click to expand...

Hi,

Many thanks for your reply as it does clarify things.

I'm glad you were amused but all i have been able to do is reach a couple of potential problem areas.

As always i may have gone a bit too deep but having read the FAQ before i posted i included as much detail as possible, i have never touched a boiler before.

My background is electrical\electoronics engineering and have analysed what i know but i know very little about this boiler or any other.

I totally take on board that it is more likely to e NTC1 due to the thermal cycling and the extremes it reaches.

The pump seems to run fine, if the NTC1 doen't cure it i will replace the comparator on the PCB.

Do you know what a good NTC1\2 should read in ohms?

Cheers,

Jon.

Hi,

I have now ordered replacement NTC1 and NTC2 which were £15 each and will fit them tomorrow when they arrive.

I also plan to reseat the PCB connectors and check that they don't have anything to do with it.

Hopefully that will resolve the problem so i don't have to pay Vaillant £230 for a fixed cost repair to replace £30 quids worth of components.

Cheers,

Jon.

JonD said:

Hi,

I have now ordered replacement NTC1 and NTC2 which were £15 each and will fit them tomorrow when they arrive.

I also plan to reseat the PCB connectors and check that they don't have anything to do with it.

Hopefully that will resolve the problem so i don't have to pay Vaillant £230 for a fixed cost repair to replace £30 quids worth of components.

Cheers,

Jon.

Click to expand...

Update:

The NTC's arrived yesterday morning and i fitted them, the new one's read 12.5KΩ the old NTC1 was 13.5KΩ but fluctuating all over the place.

Anyways that seems to have resolved the problem and the house is toasty warm this morning and i haven't had to fill the sink with the shower

Thanks Agile

Jon.