If I increase the size of all the radiators, will that affect the output of the central heating boiler?

I own a house in Spain and the boiler was replaced by the previous owner in 2013. Unfortunately I'm 1000 miles away at the moment so can't check full details of the boiler capacity. As far as I know it's a Junkers condensing combi boiler.

Here's my general question though: the house is a little cold in the winter so I measured all the radiators and compared them to room sizes on the Net. I think all the rads have been installed based on having wall and roof insulation but none exists. Insulating is difficult and prohibitively expensive because of construction methods when the house was built.

If I replace all the radiators with bigger sizes will that affect the boiler capacity? Will the system run colder? I don't really want to replace the boiler as it's new.

TIA

submitted by /u/the_real_grinningdog
[link] [comments]