OK - here's this issue again :-)
Last year we had some rads replaced and the system flushed. Boiler is a Euroflame Kitchen/Utility 90/120, conventional flue, fitted about 7 years ago.
So, reading the FAQ about how to balance the system, and going back through recent threads, I've equipped myself with an IR-77L and made up a spreadsheet as advised.
Before doing this for real, I'm noting some methodology issues/questions:
1) I tried some black sticky tape on a rad, and measured about the same temp as without it (rad has white paint). From what I can read about emissivity, that's about right - or does someone have some particular tape to recommend? I do notice that a bare copper pipe reads a quite low temp.2) Where are folks measuring the flow and return temps? On the rad itself, and if so where, or on the flow and return pipes at the point where they enter the rad? (I'd prefer the rad, it's easier to get at).
3) IIRC, the idea is to let the system come to equilibrium, and then adjust. However, with the boiler set to deliver water at 80C or so, after an hour of burning continuously, the water exiting the boiler is only at 60C. [1]4) Some of the "distant" rads are not fully up to temp after an hour - is this reasonable? [2]
[1] Seems to me, in this case, I may as well simply adjust the boiler to produce water at 60C. [2] This is a 30s house that's been extended and with little thought apparently being given to extending the central heating in a sensible way.