In North America, furnaces are the most popular type of central heating system used for home heating. There are many types of furnaces that are categorized by the type of fuel they utilize, this includes gas, electricity, oil, coal and even wood, but natural gas is by far the most common.
As the fuel source and air is ignited within the furnaces combustion chamber, it begins to burn and produce an intense flame. In turn, the heat released from the combustion process is used to heat up a metallic component known as a heat exchanger. Furnace fans then blow cold air through this structure and into the distribution system to deliver the now warm air to the rest of the property.
In terms of energy efficiency, furnaces have seen some substantial improvements in recent years, with newer high-efficiency furnaces achieving more than 90% efficiency. Multiple changes are responsible for these impressive efficiency ratings, including high-static heat exchangers, the use of electronic ignition and vent dampers.
For example, old furnace designs used to release exhaust gases straight out through the chimney or ventilation system, resulting in around 30% heat loss. Yet new models utilize an internal damper that draws a large amount of exhaust gas back into the heat exchanger where it can be re-used.
It achieves this by condensing the water vapor from the exhaust fumes, which releases the heat that can then be put to use. The exhaust fumes are then cool enough to be vented through a plastic pipe.
The following are some of the various common reasons of why a leak may be coming from the top of your water heater: