Ecotec 937 and VRC430

[shadybrady]

I have gone through a number of the topics on the use or attempted use of the vrc430 to control a Vaillant boiler.

Well I still cant get the bloody thing to work properly !!

I have played around with all the heating curve options, disconnected the weather compensator and other bits but its still not seemingly working correctly.

The boiler works fine when the vrc430 was not connected, the central heating keeps running until i drop the radiator dial or turn the boiler off - ALL Good !

BUT when I connect the vrc430 the boiler will go into pump overrun mode as soon as the vrc detects a rise in temperature - its set to Thermostatic but when the temperature in the hall rises a half a degree the boiler goes into a pump overrun / cool down cycle until it starts over again in central heating mode.

If I connect the weather compensator it gets worse as the boiler starts the pump overrun cycle every couple of minutes.

My installer has never installed one of these before and hasnt the first clue with the vrc unit.

Any suggestions - the heating curve is set to 1.8 at the moment, 18 degrees in the hall and the boiler takes an age to get to that temperature due to heating, detecting a temperature rise, going into pump overrun, cooling down, then central heating mode etc...

HELP !!

Shady

 

[picasso]

Are you sure the 430 is connected to the ebus connections and the sensor is in x41.

 

[shadybrady]

The ebus is fully connected as it communicates with the boiler fine for programming etc.

The weather compensator was connected but I pulled the edge connector as it seemed to be making the pump overrun issue worse.

The main issue is that the boiler does not keep firing until the thermostat temperature is reached, it goes into the pump overrun / cool down / cycling mode before the temp reaches 18 on the thermostat, it then starts firing again after about 15-20 minutes or so.

 

[Tipper]

My 937 has major issues running a 360f on 'analogue' control, ie managing the water circulation temp in relation to the supposed room temps. It does doesn't do it, a real failure imho. It seems to go into cycling prevention all too easily.

I have now set it back to 'digital' control which is good old fashioned on/off firing to reach room temperature and it works fine! I can now feel the heat from the rads!

Is there a similar option on the 430?

I suspect Vaillant controls are far too clever which can be evidenced by the nerdy instructions that don't tell you how to set them up.

 

[MJN]

I must say these threads on Vaillant+VRC430 really are food for thought... I am planning an eventual boiler replacement and had my eye on a Vaillant, with the VRC430 to take full advantage of it (stat controlled modulation and weather compensation) but it does seem to be trying to be too clever for its own good.

I appreciate these posts may be from a limited number of people, but they come across as reasoned experiences so I am inclined to take heed of what they say.

Will continue to read with interest...

Mathew

 

[shadybrady]

It does appear that after changing the vrc 430 to modulating it appears to function better when controlling the boiler but its still not perfect.

I am going to discuss with my plumber about flushing the system, getting it perfectly balanced to remove any possible issue with flow rate / restrictions on the pipework / sludge build up etc.

I will then test with the vrc 430 for a couple of days and maybe if it all starts working ok I may tempt fate and add the weather compensator back in.

We will wait and see...

Shady