Report "I'm a plumber and was looking at a friend's Ariston Microgenus 28 kW combi boiler today. The problem is the DHW comes out tepid, then within a few seconds of the burner igniting, the temp indicator lights on the front panel show 80 deg and the burner cuts out. The water goes cold again, the supposed temp drops to 60 and the burner fires again- but again only for a few secs til the lights show 80 again. I removed the temp sensor and cleaned it, but no difference. Does anybody know what value in ohms the sensor is supposed to be giving, so I can test it before buying a new sensor?"