A discussion in a separate thread has prompted me to look further at the
set up of my gas boiler.
I have a heating system designed & supplied by NuHeat ...... 17 zones,
all underfloor heating - no rads.

There is a thermal store (Energymaster) and if the stat on the store
(fitted on lower 1/3)is lower than 65C .. it requires heat .. zone
valve opens on primaries, pump starts and 220V sent to boiler.
Boiler runs until stat reaches 65C and opens.

The heating system us fed from a lower heat exchanger, and the DHW form
an a upper heat exchanger via a thermostatic valve.
There is no blending valve on loop circuit - design relies of store stat
limiting temp. ( I intend fitting a blending valve - but that id not
in current design)


Sketch of set up he http://tinyurl.com/ngeqfsy

Safety bypass and pressure vessels left out for clarity

The initial advice was to set boiler temp to Maxm .... but appreciate
this may not be optimum ....
I went back to NuHeat .. they advise
# Boiler stat should be set to 75C .....
# Diff between boiler F& return should not exceed 13C

Any suggestions on how to set this up ....... I have only the pump speed
and boiler temp setting to adjust.

Do I turn down boiler setting until it is at 75, then adjust pump for
13C difference ........ just not sure how to approach this.