vokera hot water problem

I HAVE A VOKERA LINEA 24 WITH A PROBLEM. THE HOT WATER WILL ONLY HEAT UP TO 66DEG THEN SHUTS DOWN GIVING ME COLD WATER, IT WILL THEN HEAT UP AGAIN BUT STILL ONLY TO 66. THE CENTRAL HEATING WORKS VERY WELL. I HAVE REPLACED TO DOMESTIC HOT WATER THERMISTOR (PART NUMBER 8484) BUT IT STILL DOES EXACTLY THE SAME. ANY IDEAS

please dont SHOUT

Check your benchmark logbook. Any system cleansers used?

I suspect system debris to be the culprit

i do not have any log books for the boiler because i have just moved into the house and do not have any info on it,

AS FOR NOT SHOUTING, i had no idea what it meant until someone told me. im not really into all this email chat ****.

hollern, i forgot to say welcome to the forums , you may also want to see this

hollern, i forgot to say welcome to the forums , you may also want to see this

this is also useful

Linea range will tell you when the thermistor is defective. I suspect the HW heat exchanger is blocked due to lack of system cleanse and treatment. I could be wrong which can only be proven by carry out system checks.

System water heats the radiators. Large areas and orfices for the water to travel. Put the same water through confined waterways (like those on a hot water heat exchanger), you soon have poor circulation if system water is sedimented

Main heat exchanger heats the system water. All this heat has to be transfered to incoming cold water during HW demand. If that does not happen, burner rate falls or even shuts down.

This occurance is very common when inox plate heat exchangers are utilised (which they are in almost all moder boilers)