getting temp down on return pipe on condenser type oil boiler?

Andy From Sligo

hi all - I've put a digital thermometer on the return pipe and when both upstairs and downstairs room stats are calling (and heat is going to rads) ive observed the thermometer and its reading around 50c on the return (not excatly 20% difference between flow and return because flow is around 60c - but I still believe its in most efficient condensing mode because the return is around 50c) however when both roomstats are satisfied its a completely different story , the only circuit running is the coil in the copper immersion tank in the hot press (which is well insulated with the green foam stuff) and the return pipe is much higher than 50c (cannot remember figure at the moment) - but I suppose its because the heat isnt dissipating like it would with radiators.

Any ideas/solutions to get that figure down for the return pipe? - would fitting a small sink radiator in the hot press get it down enough, it doesnt get very warm in the hot press (presumably because the cylinder is so well insulated) - and there are a couple of drafts in there.

I know that even when condenser boilers are not in condensing mode they are still more efficient than the old oil boilers but even so, just for piece of mind it would be great to get the temp of that return pipe down in temperature.