Most combis have an opposite flow through the plate so the cold water inlet is at the cooler return end.
The typical temperature difference from primary to secondary of the plate is 15-20 C which will easily enable condensing to occur.
If the user does not wind up the boiler DHW temp they will be very efficient.
Unfortunately its a British trait to want the DHW at 55 C and add cold water at the point of use thereby preventing the boiler from operating most efficiently.
Tony
The typical temperature difference from primary to secondary of the plate is 15-20 C which will easily enable condensing to occur.
If the user does not wind up the boiler DHW temp they will be very efficient.
Unfortunately its a British trait to want the DHW at 55 C and add cold water at the point of use thereby preventing the boiler from operating most efficiently.
Tony