Vaillant Ecotec 624 with VRC 430 shows outside temp of -50c intermittently

[neil22]

The system works except for the weather compensator showing an outside temperature of minus 50 centigrade 5 or 6 times a day ( usually for about 15 to 20 seconds each time). When this happens the boiler shuts down until the outside temp shows the real outside temp again then continues as normal.The Vaillant engineer changed many of the parts when it was under guarantee but the problem has continued.I have searched but never found anyone with the same problem.

 

[ScottishGasMan]

Is it a VRC430 or VRC430f (the f is the wireless vesrion) a temp of -50 typically means there is no connection or a short on the cable to the outside sensor, in which case they can change all they want if theres an iffy cable then it will need replacing.

A possible test would be to take the outside sensor off and wire it direct on the inside of the house on a new short cable, it will show inside temp but would then let you see if it continues going to -50 and rule out a bad cable.

 

[neil22]

Thanks for your reply , most of the electronics/ circuit boards were replaced under guarantee by vaillant engineer including the VRC430, I replaced the outside temp sensor and run a new cable but the problem persists. The only thing that was not replaced was the VR 65.I can understand a break or fault in the system but why is it intermittent and then what would cause it to reset / resume by itself?