Good morning, my name is ***** ***** I will assist with your query today.
Please give me a few minutes while I look up the engineer manual for your boiler
Iain sorry for the delay in getting back to you.
I assume you have followed the instruction in the operators manual to clear the fault -
"Er34 – Low vacuum pressure – Clear the error by holing button B for 3 seconds. Turn off the time clock for 10 seconds before switching on again."
If the fault is still present, this is most likely a sensor fault in the flue or the fan which creates a vacuum has failed, it may also be worth checking the flue hasnt become blocked.
No problem, this certainly suggests there is a fault, and at least you know you can induce it by putting it under load.
When the engineer attends its worth asking them to do a service as it may just be a case of needing to clean the flue or sensor.
Appreciate if you can rate the service received today.