HVAC systems are a prevalent source of fires, costing hundreds of millions in property damage. In 2010, the National Fire Protection Association (NFPA) reported more than 7,000 house fires related to fans, air conditioners, and other such appliances. Central and room HVAC systems were the most prone, having accounted for a third of the fires.
Reports filed between 2006 and 2010 indicated that big fires were a result of small problems left unchecked. A third of the fires reported were caused by a sudden spark in the electrical system, which can be triggered by a stray leak. Denver heating and cooling experts can think of an ideal culprit: a clogged or overflowing drain line.