i have a vaillant 435 ecotec and a "megaflow" tank serving hot water and underfloor heating. however, the water temperature is only coming out of the taps warm - not hot - despite my increasing the top dial on the boiler with the tap (water) symbol. having spoken with someone else with a 425 ecotec, they have told me that their one has a similar issue but an engineer told them that the top dial doesn't do anything and only the bottom dial (with the radiator symbol) controls both the water temperature for the heating and the hot water from the taps. is this correct and what should i set it to - currently at 65 degrees celsius?
any ideas?
any ideas?