On Sep 7, 1:20*pm, Dave wrote:
What is the efficiency difference between a 1970's double radiator to
today's double rads fitted with fins?

Dave

The efficency of a hot water system is determined by the boiler, is
this a question where he thinks you will save money in your heat bill
with new radiators? If you want to save money turn down the thermostat
and wear a jacket or you insulate your home and put in a condensing
boiler. Condensing boilers run at a lower temp, if your condensing
boiler and old radiators keep you warm then you should be very happy.