have an ace high combi model which responds and ignites to dhw demand, yet the water stays luke warm then sometimes gets to the correct temperature, i have checked dhw thermister n flow switches, all ok , could it be the diverter valve or a torn diapghram ? any help greatly recieved ?

spark, December 2008

hi, the switches are defo making a good contact n the thermistor is working correctly, i.e reducing in voltage as its warming up, n vice versa, others people have mentioned the diverter valve n a seal that tears inside it ! hate this boiler, thanks anyway billy .

spark, December 2008

Hi having same prob with mine. Check you have 4 - 5 volts on pcb X4 pins 10-11. If so, thermistor fine. Is micro switch switching on? Turn on hot tap and put a wire link accross 2 pink wires on pcb. You might need a small mirror to watch the pin on the divertor valve come out and operate the switch. If it tries but not far enough, try removing/cleaning the inlet flow regulator. 24mm brass nut, back right hand side. Contains filter and reg. Shut off cold inlet first and open all hot taps to drain. Reg is the green button with cream cog shape in middle. throw it away and re assemble.
Next, drain whole system and remove 27mm nut holding DHW switch pin on valve. Careful, strong spring and small parts inside. Clean all, lubricate with silicone and reassemble. Also try flushing system out. Think I've cured mine. Time will tell!!

Billy, December 2008