Freezing pipe prevention

[Middle France]

I wish to prevent freezing pipes during winter when my house is empty several months
I understand there is a special programme for this purpose. Please indicate how to program this on my Bosch CR 400 EMS Control Unit using as little oil as possible. Which is the lowest outside temperature I can set for the heating to start? Do all radiators need to be open? Can radiators be set low?
I have downloaded an android app valled Bosch Control, is this or another app compatible with my CR 400 EMS? I find the Instruction manual rather confusing. If nothing else I would like to activate the boiler when temperatures outside drop to below 5 centigrade (lowest recommended by Bosch) at the same time I would like the temperature inside the house to be as low as possible.
I have just bought this very large old house in the country and must leave it empty next Tuesday.
Thank you for all advice.

 

[Middle France]

I have written to the person who is taking care of the house, given her a list of heating technicians in the area that I found in the internet and asked her to please contact them if the heating technician that usually takes care of the heating continues to be unavailable. I am left with the feeling that chrisW50450 is the person who not only speaks English but is also the most knowledgeable when it comes to this particular boiler. But of course being located three hundred kilometers away is also most likely unavailable.

 

[Middle France]

Problem solved. The expert came. Apparently dirt in the fuel.