The specific heat of water is 1 calorie/gram Â°C = 4.186 joule/gram Â°C which is higher than any other common substance. As a result, water plays a very important role in temperature regulation.
Central air conditioners typically last from 10 to 15 years. The lifespan of a central cooling unit may be reduced if its capacity is not properly matched to the cooling load of the home.
 Typically a furnace or air conditioner will last 15-20 years. or ... a gas furnace should last from 20 to 25 years.. In your milieu, I'd expect at least 25 years.