Before any costly repairs, take into consideration the weather of late has been considerably colder than normal, thus the coldwater coming in to the boiler is also colder and can effect the temp at your tap, if water temp on front of boiler is at its highest and nobody has tweaked any potentiometers on the circuit board then .....
IF heat ok , but hot water not that hot? sounds like a faulty domestic hot water thermister (d.h.w. sensor) its a thermostatic resistor which senses the water temp' bringing on the boiler to heat up the water to your taps. the ferolli uses identical thermisters , 1 for hot water and 1 for heating . FIRST TURN OFF POWER TO BOILER.You can check the dhw sensor by swapping both leads over eg .lead to heating sensor (normally red) remove from sensor and swap with d.h.w sensor (normally blue) page 31 , fig 29 of boiler manual . with blue lead now connected to the heat sensor (which is known to be working ok), TURN POWER TO BOILER BACK ON. try hot water tap and see if the temp' improves if it does you've just prooved that the dhw sensor is faulty. TURN OFF AGAIN and replace wires back to correct sensors , blue lead to dhw and red lead to heat.The idea of this exercise is just to check the operation of the sensor, they are about the cheapest thing to replace on combi's and is the 1st thing i would check on this kind of boiler
papmc
February 2009
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