"Graham Jones" wrote in message
...
Why not by one thermometer, common or garden variety, for each radiator.
Place one thermometer on top of each radiator. Wait 15mins then do the
normal lock shield valve adjustment cycle until all thermometers read
the same.

Intriguing idea! You'd have to make sure that the thermal contact between
each thermometer and its radiator was the same- same position, same clip,
same conductive material etc. You can't rely just on radiated or convected
heat to give a reliable temp. Remember the inverse square law! Small
differences in separation distance can make a large difference in apparent
temp. The 'true' doesn't matter of course. You just want them all reading
the same. Alternatively you could get *one* infrared thermometer. These
respond quickly, though perhaps the radiator colour might affect the
readings?

Let us know how you get on.

Peter Scott