Older furnaces and some newer furnaces feature what is known as a conventional furnace design. Basically, your furnace will have a one-speed blower and one heat exchanger. This means that whenever the furnace comes on, the motor will run at full speed, which means that your motor will consume more electricity and fuel than the same motor would if it were running at a lower speed. Furthermore, your furnace's one heat exchanger will leave some heat in the exhaust gases that vent out of the furnace, wasting this heat that could potentially be used to heat your home. A modulating-condensing furnace can outperform any furnace that features a conventional furnace design.
What You Gain with a Modulating Furnace
When you drive a car, you get better fuel efficiency when you run your car at slower speeds. If you are constantly gunning your engine, you end up burning a lot of fuel. The same thing happens with a furnace. If your motor and burner don't run at their top potential every time you turn on your furnace, you end up with better efficiency. A modulating furnace will have the ability to run at full bore to warm up your quickly when necessary, but it will run for longer periods of time at a lower level in order to maintain the heat in your home. Even though your furnace stays on longer, it ends up consuming less fuel, which leads to greater efficiency and savings.
What You Gain with a Condensing Furnace
As mentioned above, a conventional furnace will only have one heat exchanger. It is this heat exchanger that extracts heat from the exhaust gases created by burning fuel in your furnace and then transfers the heat to the air blowing into your home. A condensing furnace will have a second heat exchanger, which extracts so much heat from the exhaust gases that they convert back to a liquid. By taking better advantage of the heat created by burning fuel, a condensing furnace will reach higher levels of efficiency.
A modulating-condensing furnace can be up to 98% efficient. An older furnace with a conventional design can be as little as 50% efficient. What this means is that if you have an older furnace in your home, you waste $50 for every $100 that you spend on heating your home. Thus, you can almost cut your heating bills in half by installing a modulating-condensing furnace in your home. If you want to see if you can afford a highly efficient furnace, then you should talk to a furnace repair professional to get an idea of how much it will cost to install a new furnace and how much you can save.