Had these fitted to our gas hobs and every time the gas hob was on for longer than 5 mins with these fitted the carbon monoxide alarm was set off! We had British gas in to check out the hob, only to discover our cooker was in full working order...the minute we tried removing the so called energy saving device the carbon monoxide alarms no longer detected anything. (We bought new carbon monoxide alarms as well just to make sure it wasn't a fault of the alarms)...a year later we have had no carbon monoxide problems since. THrowing these away was the best thing we ever did and saved embarassment at dinner parties!