Undocumented Vaillant diagnostic codes

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Hi,

Looking through the diagnostic codes on my ecoTEC plus 418 boiler, I noticed there are several 'undocumented' codes, can anyone enlighten me as to what they change / represent?

Here are the codes, available options or if it's a status:

  • d.14 -- set @ 0 -- Options=0,1,2,3,4,5
    d.15 -- Status 0-100 -- Appears to relate to how much kW the boiler is using, perhaps a % of d.0?
    d.16 -- set @ 0 -- Status (haven't seen it change)
    d.24 -- set @ 0 -- Status (haven't seen it change)
    d.26 -- set @ 2 -- Options=1,2,3,4,5,6,7,8,9
    d.29 -- set @ 0.00 -- Status (haven't seen it change)
    d.63 -- set @ 0 -- Status (haven't seen it change)
    d.74 -- set @ 1 -- Options=0,1
The reason for looking was to see if I'd missed a setting when trying to stop short cycling with a VRT392 and above boiler. If there are any experienced senior Vaillant engineers reading, I'd also really appreciate your help on my other thread here: :)

//www.diynot.com/forums/viewtopic.php?t=266773&start=60

Thanks!

UpgradeMe

P.s. Does anyone know what "d.23 Summer/Winter" actually does or how you/it changes? it's currently set at Winter.

EDIT: I've now found the meanings for all of the above codes and better explanations for d.17, d.18 & d.23, obtained from other Vaillant manuals. It would appear Vaillant are using the same software across their ranges and these are 'left over' from other boilers.

  • d.14 = Pump speed target value - Target value of internal pump in % Possible settings: 0 = auto (factory setting), 1 = 53%, 2 = 60%, 3 = 70%, 4 = 85%, 5 = 100%

    d.15 = Pump speed actual value - Actual value internal pump in %

    d.16 = Room thermostat 24 V DC on terminal 3 & 4 - 0 = Room thermostat open (no heat request), 1 = Room thermostat closed (heat request)

    d.17 = Heating flow/return regulation change over - 0 = flow, 1 = return (factory setting: 0). When connecting underfloor heating or wall heating to the appliance which does not have its own temperature regulation, the temperature regulation mode can be changed from flow temperature regulation (factory setting) to return temperature regulation

    d.18 = Pump mode (return) options are 0 = return, 1 = nonstop, 2 = winter (factory setting: 0).

    Return: Once the heating requirement has ended, the pump runs on for the time specified under "d. 1“.

    Nonstop: The pump is switched on if the rotary knob for setting the heating flow temperature is not at the left hand stop position and the heat requirement is enabled by an external controller.

    Winter: The pump is switched on when the rotary knob for setting the heating feed temperature is not in the left-hand stop position.

    d.23 = Summer/winter operation (heating on/off) - 1 = heating on (winter mode), 0 = heating off (summer mode)

    d.24 = Fan monitor - 0 = contact open, 1 = contact closed

    d.26 = Additional relay control ecoTEC
    1 = circulation pump
    2 = ext. Pump (Default)
    3 = charging pump
    4 = vapour extraction hood
    5 = ext. solenoid valve
    6 = ext. error message
    7 = not active
    8 = remote control, eBUS (not yet supported)
    9 = legionella pump (not active)

    d.29 = Actual value, sensor circulation water quantity - Actual value in m3/h

    d.63 = Number of shutdowns of the air monitoring

    d.74 = Anti-Legionella protection - 0=off, 1=for activation enabled by controller
 
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In you other thread you mentioned about the d2 setting.

Here is the table showing the effect of the d2 settings against flow temperature.

I have an Ecotec 415 plus with the flow temperature set to 65c. I have d2 set to 60, which gives an anti-cycle time of about 14 minutes at that temperature.

This gives the flow temperature time to drop to about 45C, before the boiler fires up again and reaches 65C during the first 60 seconds before it modulates down again.

This prevents it from from shutting off before it has chance to modulate down.

Keith

GALLERY]
 
Here is the table showing the effect of the d2 settings against flow temperature.

Thanks Keith (I've sent you a message, see link at top of screen), that table helps fill in the missing gaps for how d.2 operates! :)

Following my own observations, along with the above table, this is how I believe the d.2 setting works with a modulating controller (VRT392, VRC430 & perhaps others) NOTE: A 'modulating controller' dynamically changes the flow temperature it requests from the boiler.

  • Vaillant d.2 code - Example of operation

    Lets assume d.2 is set at 60, the modulating controller is currently requesting a flow temperature of 40C and the burner has already fired. The boiler upon entering anti-cycle mode starts a timer with an initial 'goal' of waiting 38.5minutes (from the Table).

    If after waiting 20 mins, the room temperature drops, the controller then changes it's flow temperature request from 40C to say 60C. The anti-cycle time for 60C is 17 mins, as the timer has already reached 20 mins, there is no anti-cycle time remaining (it's actually now -3mins) so the boiler then fires the burner again.

    [timer] - [current waiting time from Table] = [d.2 time]

    Initially that would have been be 0-38.5=38.5mins then changed to 17-20=-3mins
The above example is assuming a modulating controller set in 'analog' mode where the flow temperature demand is dynamic. If set to 'two-point' mode (or using a.n.other room stat), the flow temperature is static and set via the dial on the front of the boiler. As an example for a static flow temperature demand, if the boiler was set at 65C, after it enters anti-cycle mode the boiler will wait 11.5 minutes before firing again with d.2 set at 60, or 4.5mins with d.2 set at it's default of 20.

EDIT: The following is Vaillant's explanation for d.2 found in this manual:

Vaillant ecoTEC Exclusive manual said:
The burner is electronically locked for a specific time after each time it is switched off ("re-start interlock") to avoid frequent switching on and off of the burner (energy losses).

The burner anti-cycle time is only activated for the heating operation. Hot water operation during a burner anti-cycle time does not affect the timer. The individual anti-cycle time can be matched to the hydraulic and thermal properties of the heating installation. In the factory the burner anti-cycle time is set to a value of 20 minutes. It can be varied under diagnosis point "d.02" within the range 2 minutes to 60 minutes.

The individual effective anti-cycle time is calculated from the momentary target feed temperature and the set maximum burner anti-cycle time. The timer can be reset or cancelled by actuating the appliance main switch. The remaining burner anti-cycle time left after switching off by the controller in heating operation can be called up under diagnosis point "d.67". The individually effective burner anti-cycle times with respect to the feed temperature and the maximum set burner anti-cycle time can be taken from Table 7.2.
 
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I don`t have any of the extra Vaillant external controls, only a Drayton 3 port valve and tank thermostat which is set to 50C.

Setting the flow temperature to 65C is a good compromise, and gives a reasonably quick hot water recovery time.

I also have the pump overrun set to 18 minutes, to allow a more even distribution of hot water throughout the different sized radiators during any anti-cycling time.
It also stops the pump cycling on and off, which is annoying, and must increase the wear and tear.

Anti-cycling only occurs when the radiators are all hot, and the 5Kw minimum output is still too high.

Keith
 
I also have the pump overrun set to 18 minutes, to allow a more even distribution of hot water throughout the different sized radiators during any anti-cycling time.
Doesn't the pump stay on anyway during anti-cycling?
 
Doesn't the pump stay on anyway during anti-cycling?

Oddly enough it does not. If you leave it at the default of five minutes, then it turns off after five minutes.

Then it restarts again just before the boiler fires up again.

I find it better to keep the pump running longer, because it also reduces the chance of the boiler shutting off before it has chance to modulate down. It outputs 12kw during the first 60 seconds, so unless this can be dissipated, the temperature will rise above about 66C, and it will shut off.

Provided the return temperature has dropped to 45C, then the boiler will fire up again without short cycling. This takes about 14 minutes.
 
I also have the pump overrun set to 18 minutes, to allow a more even distribution of hot water throughout the different sized radiators during any anti-cycling time.
Doesn't the pump stay on anyway during anti-cycling?

I've edited my 1st post in this thread with explanations for the codes I've found so far, including a much better explanation for d.18 (pump mode) which will affect the above operation.
 
It outputs 12kw during the first 60 seconds, so unless this can be dissipated, the temperature will rise above about 66C, and it will shut off.

I've heard rumours that this behaviour can be modified, however by doing so the boiler may not conform to regulations (I expect something to do with emmisions?) - If anyone reading knows how to change this behaviour / setting, I'd be really grateful if could you let me know how it's changed? (perhaps via private message) Thanks! :)
 

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