requiring high voltage is that the appliances are rendered useless during a power outage. Pilot light solutions work independently of the electrical system. However, some appliances can be lit with an external flame source during a power outage. This may include cooking stoves and ovens, but not heating boilers that are either room-sealed or rely on electricity to operate pumps. Another disadvantage of using burning appliances connected to natural draught chimneys without pilot lights is the lack of the starting draught in the chimney. Without a pilot light the chimney can cool down completely to the outside temperature, therefore there is no chimney draught this case at all, or there can be even a negative chimney draught if the outside temperature is higher than the inner temperature in the house. This case there is a backflow in the chimney. This is the reason of feeling the smell of soot at summertime at the chimneys openings. If there is a backflow in the chimney, it is possible that the cool air and the hot flue gases both entering into the appliance’s room via the openings of the gas appliance draught diverter, which can cause high level of carbon-monoxide in the air of the room, resulting possible deaths or permanent disability. In such a situation there is no strong physical effect which would drive the flue gases into the chimney, so the power, which cause the backflow in the chimney can be determinative. According to statistics the “starting draught” in chimneys assured by the permanent pilots has an important role to prevent an increase in the number of carbon monoxide poisonings. So in case of open fired appliances and natural draught chimneys the goals of the energy savings and the safety aspects are opposite. References Heating, ventilation, and air conditioning