Got my HA code running . Heating for entire above ground if temp drops below 17c then off at 18c
I deliberately did a tight range . Heating came on just after midnight , turned off just after 9am . So effectively I ‘leaked’ 1 degree in 9 hours ( outside temp now around 7c )
Electric consumption for yesterday was around 12kwh .
Although not a particularly scientific test - that seems pretty good too me