What Is a Modulating Motor?
Older furnaces will have a one-speed motor. By force, such furnaces must come on full blast whenever the temperature in your home begins to fall. Once your home warms up to your target temperature, the furnace shuts off. This is equivalent to gunning your engine after you hit a stop light—you burn through a lot of fuel. However, when you maintain a consistent speed, you end up using less fuel. A modulating motor will have the ability to run at multiple speeds. Thus, your furnace can come on full blast to warm your home quickly, but it will then run at lower speed for a longer amount of time and more frequently to help maintain a consistent temperature. The end result is that you end up using less fuel.
What Is a Heat Exchanger?
Your furnace will burn fuel in the aptly named burner. The resultant super-heated exhaust gases will then enter a heat exchanger. As they flow through the
Why Use a Second Exchanger?
A conventional furnace will leave enough heat in the exhaust gases that they are able to rise out of your home through a vent pipe. The problem with this solution is that the heat in the gases is simply wasted and your furnace will never be as efficient as it could be. Highly efficient furnaces will have a second heat exchanger that absorbs so much heat from the exhaust gases that they condense to a liquid. This liquid exhaust must then be drained out of your furnace through a drain pipe.
If you are looking for the most efficient furnace on the market, you should look for a modulating, condensing