Vaillant Ecotec 4xx startup protocol

[MHOL]

I have an (old) Ecotec 415. My observation is that it always starts at 12kw for approx 1 minute, pauses for 5 seconds then starts again at d0 power before modulating down as required. This large power start results in high temperature rise and means that the boiler cannot restart after cycling for an unreasonable length of time.

Users of recent Ecotec 418s report that they observe 70 or 80% of d0 for only 20 seconds before modulation.

I have described in other posts the problems I have with the boiler in my small well-insulated house when used with VRC430 and weather compensation. I have made many tuning efforts and the final result is reasonable but needs manual intervention to achieve anything other than steady state running.

I was excited about the reported behaviour of 418s which I took to be news of changes made by Vaillant in newer 4xx boilers. I wrote to Vaillant to find out if my boiler could be upgraded to match. What I have been told so far is that no changes have been made to the 415. My assumption would have been that all the 4xx boilers would have the same starting protocol.

I'm wondering if owners of Ecotec 4xx boilers or installers would like to post up what happens on their boilers. The approximate age of the boiler together with the model number would be useful. At this stage I think timings and power estimates based on the apparent roaring of the beast would be quite good enough.

 

[Gary27]

I have a similar issue, the boiler from cold will fire when heat it required and run for approximately 60 seconds on full or near full power then modulate down to d0 setting and then modulate further when target flow temp is reached.

The issue I have is that when the flow temp is reached and the boiler has modulated al the way down which is believe is 5kw eventually the boiler exceeds the temp and cuts out. Now for reasons I only partly understand the boiler waits before it restarts, this can be seen in d67, sometimes it will be 20mins and sometimes as low as 1min. So when the restart time d67 is 1min when it fires on full to near full power it overshoots the target flow temp within seconds. This will continue over and over again and as yet it have not found a solution.

To try and alleviate it I have set the minimum flow temp to 50c and set d2 to 60. Pump set to maximum, and all radiators on. The house is a 4 bed modern detached well insulated. The boiler is de-rated to 10kw

I have a 6 month 418 with weather compensation.

Any ideas anybody?

 

[ALEC1]

I would go here...

http://vaillantcyclingproblem.blogspot.com/

 

[David937]

This is a well documented issue with the Vaillant 400 series, mostly when used with some sort of modulating controller, WC and the like. I doubt majority of owners know of this issue* and I doubt they even care.

*Particularly installations without WC, the flow temperature would just be set to ensure the cylinder is heated to 60ºc and the house will reach the desired temperature all the time, typically 70ºc +

 

[ALEC1]

your point being?

 

[David937]

Vaillant won't do much as it's not such a widespread issue as such