Vaillant Ecotech Pro 28 Slow start

[AndyG187]

Hello all,



Im wondering if you can help?



Ive got a Vaillant Ecotech Pro 28 which was installed 9 years back and has worked like a dream all its life, however this Autumn I've unfortunately started to face issues with it. I've noticed that its taking 10-15 mins for the CH to kick in when sending a signal for CH, the hot water on the other hand is working absolutely fine, no issues.



These are the steps of action

1. Send signal via Nest to switch CH to a higher value then room temp

2. Radiator symbol starts flashing

3. 20 seconds later you can hear the boiler firing up

4. 10 seconds later the boiler stops firing up

5. 10-15 mins all you can hear is the fan running

6. After 10-15 mins the boiler finally starts up.



I have not done anything whatsoever to the boiler over the summer and the above has only started happening over the last few weeks.



Im very puzzled as all was completely fine for many years. I've read online and people have mentioned changing the D.0 setting (whatever that is!?) would help and do the trick but I dont know where to start.



Again, just to confirm HW is working as normal its only the CH when being called upon having a delay in start up.



I own a 3 bed Semi with a total of 9 Rads in the house ranging from small (600mm) to large (1800mm) double rads.



ANY HELP on what it could be or what I can change would be super helpful. Also note I am not getting any error messages whatsoever on the screen apart from the Rad symbol flashing.



Thank you all so much for your time.



Andy

 

[Johntheo5]

This should be your model, you should be able to find how to access the d parameters in it, if d.000 is set to auto, change it to say 18/20kw, you are limiting (range rating) the boiler output ~ to the CH demand, try it and see if it helps.

 

[AndyG187]

Thanks Johntheo5 for the reply, so after research ive found how to get into the D menu, a boiler was set to 24KW i changed it to AUTO but didnt see a difference, you think if i lower the value as you said to 18 or 20 it may behave differently?

 

[CBW]

Could be diverter on its way out, or intermittent fault on receiving signal from the heatlink.

 

[Johntheo5]

Thanks Johntheo5 for the reply, so after research ive found how to get into the D menu, a boiler was set to 24KW i changed it to AUTO but didnt see a difference, you think if i lower the value as you said to 18 or 20 it may behave differently?

Unlikely that the 24kw setting would have caused any problem IMO.
Suggest doing steps 1 to 4 again and closely watch d.040 & d.041 (boiler flow&return temps) and note the readings for the 10 secs or so until the burner trips.

 

[AndyG187]

Unlikely that the 24kw setting would have caused any problem IMO.
Suggest doing steps 1 to 4 again and closely watch d.040 & d.041 (boiler flow&return temps) and note the readings for the 10 secs or so until the burner trips.

Thanks I will do that this evening and come back to this thread. Thank you kindly so far for your support.

 

[AndyG187]

Hi Johntheo5 so i fired up the boiler again last night but was not in time to capture the values at the start however i let the boiler run and it then stopped again 10 mins later, the values I captured where after 5 mins of it being off were

D40 = 54
D41 = 51

Does that sound right?

Thank you.

 

[AndyG187]

Also just to add it fired up again and while fired up the values are

D40 = 70
D41 = 61

D71= 75 degrees

 

[Johntheo5]

Hi Johntheo5 so i fired up the boiler again last night but was not in time to capture the values at the start however i let the boiler run and it then stopped again 10 mins later, the values I captured where after 5 mins of it being off were

D40 = 54
D41 = 51

Does that sound right?

Thank you.

You must try and get those values "immediately" or watch them as its stopping, not the easiest task!!

Also just to add it fired up again and while fired up the values are

D40 = 70
D41 = 61

D71= 75 degrees

d.40 should reach the target temperature d.71 in say 10 minutes or so but if it overshoots it by 5C (80C) then the burner will trip.

Next time its running normally check that d.40=d.75, the increase d71 to 80C ,if possible, and watch d.40, if ok reduce slowly back down to 75C.