I understand from googling that a radiator should have about a 12deg C differential between flow and return.
Does the same logic apply to the boiler flow and return.
If a boiler circuit attemps to reduce cycling it may hold off untill the return temp is 12 deg less than the flow before firing.
In this case for maximum efficiency should the continue to run untill the either of the following is acheived.
a) fire boiler untill flow temp reaches desired target (i.e 80deg etc) regardless of return temp (i.e also allow to return at say 80deg) b) room stat is satisfied
OR
a) flow temp reaches desired target (80deg etc)/boiler stat b) return temp is less than 12 deg below flow (i.e if boiler is heating to flow to say 80deg, at at 60deg the temp of the return is say 55deg should the boiler switch off anyway? c) room stat is satisfied
I suspect the second is preferable, as this would take into account that not much heat is being lost in the system (i.e warmer house) and compensate accordingly.
Any thoughts which is best? or your own theory!