My main critique of the Intergas is the thermal mass of the heat exchanger which has to be wasteful of heat when this mass of metal is heated to deliver a few litres of hot DHW and then cools down before the next few litres of hot water are drawn off a few minutes later.Can you not back up your own assertions with actual facts and figures?
By comparison the thermal mass of a coiled tube heat exchanger is small and much less heat is wasted in heating up the metal of the heat exchanger.
I have aked here and not yet been answered if anyone has a copy (or can quote from) the test procedure used to measure the efficiency of domestic boilers. ( BS 303 -5 ? )
Specifically I am looking for the answer to whether the boiler has to be run up until it is in a steady state condition before any measurements are made.