This Genus 27 is similar to the earlier Eurocombi. It has a SIT 837 tandem valve with the modreg below it. With no htg or dhw demand, the boiler just buzzes from the modreg. Remove a modreg terminal, it stops. Boiler wont fire at all. Advice from Ariston is to replace left control pcb 953045 or thermister. Disconnected all sensors, it still buzzes. Bought and fitted control the pcb, no change. If I rotate the htg/dhw control to dhw, it activates the pump and buzzing subsides, most strange. control to htg doesnt change symptoms.
If one of you experienced on ariston could help would be appreciated. Im thinking about the psu 952981 pcb next which carries the relays. Expensive speculation though, so rather I heard from one of you highly experienced guys this weekend please.
update: I found the overheat sensor is showing short is that correct? Still didn't solve. I've since removed the multi way able between the left and right pcb's and the pump starts up so something is triggering this on the psu side. Obviously the modreg doesn't buzz as its been isolated in this way. So strangely, all points to the power supply pcb with all the relays. I've checked The 4 relays all energise when powered. What is the little blue box on the psu? sounds like a miniature relay too, or filter. Help pls see album.[/img]
If one of you experienced on ariston could help would be appreciated. Im thinking about the psu 952981 pcb next which carries the relays. Expensive speculation though, so rather I heard from one of you highly experienced guys this weekend please.
update: I found the overheat sensor is showing short is that correct? Still didn't solve. I've since removed the multi way able between the left and right pcb's and the pump starts up so something is triggering this on the psu side. Obviously the modreg doesn't buzz as its been isolated in this way. So strangely, all points to the power supply pcb with all the relays. I've checked The 4 relays all energise when powered. What is the little blue box on the psu? sounds like a miniature relay too, or filter. Help pls see album.[/img]
