I have installed two new Worcester 30 CDi system boilers at home. (They work in tandem, at the same time, as if they were one unit)

According to the user's manual, under "Tips for Energy Conservation", if the property has TRVs and room thermostats (which is my case), the boilers should be set at the maximum temperature setting and use the thermostats and TRVs to regulate the temperature as needed in each room.

I certainly agree that that arrangement gives the most flexibility. However, based on my reading of condensing boilers, the most condensing and thus, the highest efficiency is achieved at 55 degrees Celsius.

If I set the boilers to the maximum the boiler's water reaches about 92 degrees.

If I use a 5 setting, 7 being the maximum, the boilers' water is about 62 degrees and still gets the house warm enough (at least now that it is not too cold outside)

What is then the most energy efficient setting?

Thanks,

Antonio