Vaillant ecoTEC 428 Not igniting

[Wirelessroamer]

Boiler is working in an old vented system with roof tank and was comissioned 10 years ago. It has been serviced annually, last time Oct 2020.
House has 10 radiators. 4Bed Detached.

For several years I have had problems with my CH and HW systems which I put down to a faulty 3 way Divertor. (Drayton TA/M4) controlled from a RB2 relay.
I employed a Corgi registered heating Engineer to replace it with a Honeywell V4073 Mid position valve and replace the HW cyl thermostat.

Status before work.

3Port divertor had to be manually operated to select HW, CH or both.

HW Temperature was dependent on CH temperature

Burner fired up automatically from Timer and ran without any intervention..


Status now.

Timer powers Boiler for HW and CH but
For CH
1> Burner does not start automatically but fires up when triggered manually.

2> once the burner is fired the Boiler indicates Full Heat (SF.h) for the above process which runs until radiators are up to temp then switches off.

3> Subsequent CH needs have to be triggered by manually starting Burner.

4> Whilst idle and by pressing i the Status S30 shows no call for heat.
There is no image of a radiator in the indicator panel only a tap. Pump running and Burner displays as normal.

For HW
I ran down the HW in the tank to reduce its temperature and create a demand. (40C)

I switched off the CH at the Timer and manually ran the HW to prove the diverter was operating.

It ran until the HW was up to temp (58C) set by thermostat and switched off.

No faults are indicated on the Boiler but I can’t get it to run diagnostics.
I thought the S30 showing no call for heat was a reason for the Burner not starting when the Boiler got power but it doesn’t fire up for the HW either and the thermostat does work..

I think we have proved the wiring is ok.

I can interrogate the first level Diagnostics from the control panel but cannot change any settings.
I am unabler to access the second level diagnostics thereby trigger a restart with factory settings.
I can't get the P0 to P6 test programmes to run or force a restart from the flame button.

Any ideas?
Both HW and CH seem to run correctly when the burner is manually fired as no faults are indicated.

 

[CBW]

What is the current status? How do you know the thermostat works? Have you tested the 3 port motorised valve?

 

[Wirelessroamer]

Hi Chris.
Status the same. I have to get up early to fire up the Burner.
HW Thermostat is new and I lowered the setting before I ran the HW only test yesterday. HW temp dropped in response.
CH Thermostat is a Towerstat Wireless one. If I raise the demand temp during a heating cycle it stops the cycle.

The 3Port Valve is New (New old i.e. unused but in stock)
I had to manually reset it once.

During the installation we ran a new 3 port device with status indication over the same wiring and it responded correctly.

 

[Reddwarf4ever]

Changes should be possible to the 1st diagnostic level, always write down the value before changing anything, E.G. D0 limits the KW the boiler can produce, yours is I assume 28KW, so can set this down to the minimum the boiler can produce, mine is 5KW D5 displays the target temperature, can’t be changed from her as it’s display only, D41 shows the inlet temperature D40 the outlet temperature D1 & D2 can be adjusted, been suggested to me to change both to 3 minutes

the 2nd level diagnostic is accessed via D97, password 17 Simply enter the value and the 2nd level diagnostic settings will also be available. I would not change any of these without very good reason and confirmation of the validity.

good luck