Hello Romano, sorry to have to welcome you to the forum with your first posting being a problem. The manual doesn't say it has 2 heaters but once your consultant gets back to you, the problem will be sorted. It may have to go away to be checked by the technician unless she/he has heard of this problem before and can sort it out easily. At least you've done the testing yourself and proven something is not quite right - up here for thinking. Hope the problem can be fixed quickly for you and if you don't hear back from the consultant today, I'd be giving H.O. a call. Freecall 1800 004 838.