A furnace must extract heat from the fumes created by combusting a fuel and then use the heat thus extracted to heat your house. These fumes are poisonous, so they cannot be allowed to enter the living spaces of your house. Herein lies the main dilemma facing furnace designers: How do you extract heat from the gas fumes without letting them enter your home? Traditional furnaces allow the fumes to rise out of your house through a vent pipe dedicated to this purpose. Recognizing that you lose some heating efficiency with this method, furnace designers have created the condensing furnace to extract even more heat from exhaust gases.
The Limitations of the Less Expensive Conventional Furnace
A furnace uses a heat exchanger to extract heat from the fumes flowing through it. An exchanger consists of several metal tubes, which direct the fumes from the combustion chamber to a vent pipe. A fan pushes air over the outside of these tubes so the fumes and the air flowing into your house never mix. As the air moves over the exchanger, heat transfers from the gases heating the walls of the exchanger on the inside to the air cooling the tubes from the outside. In a conventional furnace, the exchanger is sized so that the air cannot cool the fumes completely before they leave the exchanger. This leaves enough heat in the fumes that they are able to escape your house through the vent pipe.
The Advantages of a Cost-Saving Condensing Furnace
A condensing furnace contains a second heat exchanger that allows the air flowing through your furnace to cool the fumes in your furnace to the point that the water vapor in the fumes condenses to a liquid. The remaining components in the fumes can then dissolve into the water and be vacated from your furnace through a drain pipe. These design changes help to make a condensing furnace up to 98% efficient as compared to the 82% efficiency of a conventional, or standard, furnace.
You will pay more on the front end to buy a condensing furnace, but you will save money over the life of your furnace. Talk to a furnace installer, such as those at Bill Rhiner's Plumbing, Heating & Cooling, to find out how efficient your old furnace was and how much money you stand to save by upgrading to a condensing furnace. As long as your financing costs are not more than your energy savings, you will save more money than you spend on a condensing furnace.