Thanks for the replies, everyone.

Okey dokey: UPDATE. After downloading chapter and verse on pumps and nozzles from Danfoss (I couldn't find te precise document mentioned above but I found some others) I becmae convinced that I wasn't going to be able to do anything myself as I kept coming back to needing to know the heat capability for my boiler in order to size the nozzle and pressure together. I also kept finding words to the effect of "your boiler will have this information written on it", so once again I set off in search of it.

Turns out that if I remove the control panel from the boiler and look at the back of its casing, there is a dogeared sticker with all the information on it. Talk about making it easy to find - NOT! :-)

Anyways, the nozzle size is correct and it looks like the oil pressure is 140psi, which is damn close to 10bar which I think is the factory setting for the BFP11R3 pump so hopefully no actual adjustment will be necessary.

Now I know the nozzle size and pressure I can find out what the oil flow and boiler power are.

Woo-hoo!