vaillant thermistors

[lor]

hi,
has anyone experienced problems with these?
I have a job where an ecomax 18e pro (conventional boiler on a sealed system) is tripping the manual reset over heat stat.
the fault code stored in the boilers memory shows the flow temps 18-20oc at the time of overheat ???
boiler will run fine for 8 days then trip
has a new auto bypass and pump
thanks

 

[corgiman]

how far away is the boiler from the controls lor?

we had this before and found that it kept tripping out due to temp diff on the return is it werent gettin hot kwik enough. and kept cycling untill it did, nearly drove my guv insane it did.

we moved the boiler closer and had no more probs

maybe Dave GAs4u our resident Vaillant man has a clue why? cos I dont

 

[Agile]

A mechanical overheat stat will trip when it reaches its rated temperature.

If the boiler showed just 20°C at that moment then I would suspect the sensor is unreliable and told the boiler to apply maximum power because its too cool. The resulting overheating will cause the o/h stat to trip.

I went to a boiler today where the sensor was 35K instead of 4k. The previous muppet engineer had not made any resistance measurement and assumed it was OK because there was no fault code displayed.

Tony

 

[corgiman]

what about our experiance tony?

once we moved the boiler it was dandy, just a note thou I had nowt to do with it just heard about it during a "team building" excercise IE buy the Guv a pint night



mind you no one said that it tripped out, just kept cycling like a wotsit for an age.

 

[scatmanjohn]

A mechanical overheat stat will trip when it reaches its rated temperature

Apart from when it trips before it reaches its rated temperature

 

[lor]

sorry corgiman , dont understand wot u mean.do u mean distance of boiler from 3port valve ? does it try to matian the temp diff within a preset range eg 20oc ?

 

[Agile]

Vaillant boilers design in some unallowable situations such as if you run the heating for 20 minutes and the return does not get warm then it thinks something is wrong.

Thats fine for Herr Smits three bed house on the Bannerstrausen but if you are heating Windsor castle it might well run for 20 minutes before the return gets warm.

Those are only examples of where the expected does not happen.

Tony

 

[corgiman]

sorry corgiman , dont understand wot u mean.do u mean distance of boiler from 3port valve ? does it try to matian the temp diff within a preset range eg 20oc ?

thats what i suggesting mate, agile has explained it above better than I would

 

[chrishutt]

Thats fine for Herr Smits three bed house on the Bannerstrausen

Perhaps you meant Herr Schmidt and the Bahnstrasse, Tony?

 

[Rob]

Thats fine for Herr Smits three bed house on the Bannerstrausen

Perhaps you meant Herr Schmidt and the Bahnstrasse, Tony?

LMAO

 

[Agile]

No wonder my Christmas cards get returned!