W
Whyme
Just found this out recently that commercial boilers only slightly bigger than domestic in kw that have a bigger case/ heat exchanger etc are more efficient. apparently it because domestic boilers with there fit in cupboards design have to have a smaller heat exchanger thus have to have the co2 lower and o2 higher to burn slightly cooler so not to knacker the tiny heat ex. bigger less restrictive heat exchangers can have a better more efficient mix ie slightly less o2 ( without a cooler lean flame) thus burning the gas more efficiently and getting closer to that sweet spot...
