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Vaillant Ecotec plus 418 - why constant F23 fault? I had this boiler installed two and a half years ago. It was working fine until last Sunday when it all shut down, no HW or CH and displayed the F23 “System shut down Temperature spread too large” fault. Plumber came and replaced the pump. All...

Hi I had a Vaillant eco TEC plus 418 boiler installed last month. It seems to be working fine except that every day/ night it comes on once briefly for about 10-15 seconds outside the timed periods and then switches off e.g. 3.10pm on Wednesday, 2.10pm on Thursday etc. This doesn't matter...