We have in our old building apartment or oil heating. At the beginning of the heating season, it was smoking from the oven, put it monoxide over the fireplace in the apartment (extreme high-pressure situation) the carbon monoxide Warner struck quickly and we were able to equal notify ventilation and smoke polluters to check his stove, which had gone out and has almost all house filled with smoke. A must for all those who have open fireplaces in the house or fosil heating (pellets, oil ...). He has saved us gesundheilichen damage or even more.