These days, you can find a furnace that will run at 98% efficiency. Older furnaces are not built to be as efficient as newer furnaces, so you might think that all you have to do is replace your older furnace to make your home more energy efficient. This simply is not true. You also have to consider how your ducts play into your home's overall energy efficiency.
How Ducts Can Undermine Efficiency
The air running through your ducts day after day creates outward pressure on the surfaces of your ducts. Over time, this pressure can create leaks that siphon off heated air before it has a chance to reach the rooms it is supposed to warm. This means that there is a smaller volume of air available to heat your home, and your furnace will run longer and harder than it should.
What to Do about Leaky Ducts
If your ducts are enclosed inside the drywall of your home, you will have no choice but to call in heating and air conditioning professionals to inspect your ducts and repair any leaks that they find. On the other hand, if you have exposed ducts running through your attic, crawlspace, or unfinished basement, you can inspect your ducts on your own in this way:
1. Turn your thermostat to the fan position.
2. Access your ducts and light a stick of incense.
3. Run the incense along the joints and seams in your ducts.
4. Use a marker to identify any places where air escaping from your ducts disturbs the incense smoke.
5. Once you have inspected the full length of your ducts in this way, turn the thermostat to the off position.
6, You can then paint over the marks you have made with a thick layer of duct mastic.
7. Give the mastic time to set before you turn your furnace back to the heat position.
In that leaky ducts can decrease your furnace efficiency by up to 40%, maintaining ducts is an important part of getting the best performance from your furnace. If you have an older furnace that is already running at about inefficiently, leaky ducts can decrease that efficiency even more, and if you have a new furnace running at 97% efficiency, your ducts can still drop your overall efficiency to around 58%. Either way, it just makes sense to keep your ducts running at their optimum level.