our sx20 has a fault with the hot water when we turn the tap on we can only get hot water when the c/h switch is on.Fan pump and flame works in this mode but nothing happens in summer mode.Water and heating thermostats appears to be working.When you turn them it alters the flame. We have changed the divertor valve on advice.Everything was working when we moved in 2yrs ago but over a period of time it would work on and off until now. When running hot water it would also go cold and then hot.

james harpur, April 2007

pump proving microswitch on the left of boiler near pump not making or cold water to the divertor valve could be blocked restricting the flow of mains cold water

dd, July 2008

Its only a guess, but my ariston euro combi sometimes goes cold due to a low tap setting, ie im not running enough water in the shower. It seems that i have to run it harder to get warm water. Ok hope it helps. Oh yeah, before you go the 'new pcb' route think this - 'what could go wrong on it?'. Answer could be as simple as a loosely soldered joint. I had the problem of the boiler cutting out - even during a shower, and sometimes not coming on in winter. So i thought blow this, i wiggled a wire to the pcb just the flame was refusing to light up and suddenly i got ignition. Taking the board out i found it easy just to de-solder and re-solder all suspect looking joints. My problem seemed to be that the joints were loose on the ignitor (black box). After putting it back i've had NO PROBS!

Ilya, May 2007